{"name":"GenetixBay diagnosis graph","version":1,"schema":"symptoms, causes, questions, tests (v1)","source":"real","url":"https://genetixbay.com/knowledge/diagnose/","license":{"name":"CC BY-SA 4.0","url":"https://creativecommons.org/licenses/by-sa/4.0/","attribution":"GenetixBay Knowledge Base (genetixbay.com/knowledge)"},"note":"Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.","counts":{"symptoms":142,"causes":102,"questions":38,"tests":31},"graph":{"version":1,"source":"real","symptoms":[{"id":"sym-yellow-lower-leaves","label":"Lower (older) leaves turning evenly yellow","aka":["bottom leaves yellow","old leaves yellowing","yellowing from the bottom up","fan leaves going yellow at the bottom","lower leaves lemon yellow"],"location":["old_growth"],"pattern":["uniform"],"colour":["yellow","pale"],"progression":"Starts on the oldest fan leaves and climbs; affected leaves go fully yellow, then brown and drop.","photo_cues":"Even pale-to-lemon yellow on the whole blade of the lowest fan leaves, veins yellow too; upper plant still green.","article":"kb-diagnosis-yellowing-lower-leaves"},{"id":"sym-whole-plant-pale","label":"Whole plant pale or lime green","aka":["plant looks washed out","light green all over","pale green plant","lime green leaves","plant lost its colour"],"location":["whole_plant"],"pattern":["uniform"],"colour":["pale"],"progression":"Gradual over 1-2 weeks; no single starting point, or slightly worse low down.","photo_cues":"Uniform light-green canopy, no vein pattern, no spots; compare with a healthy plant of the same cultivar.","article":"kb-answers-whole-plant-pale-green"},{"id":"sym-interveinal-yellow-old","label":"Yellow between the veins on older leaves, veins stay green","aka":["green veins yellow leaves bottom","interveinal chlorosis lower leaves","tiger striping on old leaves","bottom leaves yellow with green veins"],"location":["old_growth","interveinal"],"pattern":["interveinal"],"colour":["yellow"],"progression":"Faint yellowing between veins on lower and middle leaves, sharpening into a green-vein, yellow-blade pattern, later with brown patches; moves upward.","photo_cues":"Christmas-tree pattern: green midrib and veins on a yellow blade, on lower fan leaves; margins may stay green.","article":"kb-nutrients-magnesium"},{"id":"sym-yellow-margins-old","label":"Yellow edges and leaf teeth on older leaves","aka":["edges of bottom leaves yellow","yellow serrations","leaf edges turning yellow then brown","yellow rim on old leaves"],"location":["old_growth","leaf_margins"],"pattern":["edges"],"colour":["yellow"],"progression":"Yellowing starts at the serrations and margins of older leaflets and moves inward toward the midrib, then turns to tan scorch.","photo_cues":"Yellow band along the toothed margin of lower leaflets, centre still green; later a tan crispy rim.","article":"kb-nutrients-potassium"},{"id":"sym-yellow-new-growth","label":"New growth evenly pale or yellow","aka":["top leaves yellow","new leaves coming in yellow","yellow tops","pale new growth","new growth lime"],"location":["new_growth"],"pattern":["uniform"],"colour":["yellow","pale"],"progression":"Newest leaves emerge pale and stay pale; older leaves remain green.","photo_cues":"Whole new leaflets uniformly pale yellow-green including the veins, strongest at the leaflet base; lower canopy dark green.","article":"kb-diagnosis-yellow-new-growth"},{"id":"sym-interveinal-yellow-new","label":"Yellow between the veins on the newest leaves, veins green","aka":["new growth yellow with green veins","interveinal chlorosis top","yellow new leaves green veins","iron chlorosis look"],"location":["new_growth","interveinal"],"pattern":["interveinal"],"colour":["yellow","pale"],"progression":"Starts at the base of the youngest leaflets, spreads over new and expanding leaves; severe cases go almost white.","photo_cues":"Smooth, fine green vein network on a pale-yellow blade, only on the top one or two nodes; lower leaves dark green.","article":"kb-nutrients-iron"},{"id":"sym-netted-yellow-upper-spots","label":"Netted yellowing on upper and middle leaves with small tan specks","aka":["mottled yellow upper leaves","yellow mesh pattern with spots","netted chlorosis","yellow between veins with brown dots"],"location":["new_growth","interveinal"],"pattern":["interveinal","spots"],"colour":["yellow","brown"],"progression":"Yellowing spreads outward from the leaflet midrib on upper-middle leaves; small tan dead specks appear between the veins later.","photo_cues":"Coarser, more netted vein pattern than iron, sitting one or two nodes lower, with pinpoint tan necrotic spots between veins.","article":"kb-nutrients-manganese"},{"id":"sym-white-new-growth","label":"New leaves almost white","aka":["white new growth","albino tops","new leaves bleached white","ghost leaves"],"location":["new_growth"],"pattern":["uniform"],"colour":["white","pale"],"progression":"Develops from pale-yellow new growth (iron, manganese) or appears at the top under strong light.","photo_cues":"Cream to white newest leaflets; note whether the whitening is only nearest the lamp (light) or also on shaded tips (nutrition).","article":"kb-diagnosis-yellow-new-growth"},{"id":"sym-yellow-new-margins","label":"Yellow then tan edges on new leaves","aka":["new leaves brown edges","yellow margins on top leaves","edges of new growth dying"],"location":["new_growth","leaf_margins"],"pattern":["edges"],"colour":["yellow","brown"],"progression":"Marginal yellowing on newer leaves along the teeth, developing into irregular tan dead patches at the edge.","photo_cues":"Tan, irregular necrosis along the serrations of upper leaflets; contrast with K, which hits old leaves.","article":"kb-nutrients-zinc"},{"id":"sym-bleached-top-leaves","label":"Top leaves or bracts bleached white or yellow nearest the light","aka":["light bleaching","bleached tops","white tops","top colas turning white","sun bleached leaves"],"location":["new_growth","buds"],"pattern":["uniform"],"colour":["white","yellow"],"progression":"Only the leaves and bracts closest to the lamp whiten; shaded leaves at the same height stay green. Appears over days after a light change.","photo_cues":"White or pale-yellow top leaves and bud tips directly under the fixture, sharp cut-off where a leaf shades another.","article":"kb-environment-heat-light-stress"},{"id":"sym-yellow-middle-leaves","label":"Middle leaves yellowing first","aka":["middle of plant yellow","mid-canopy yellowing","yellowing in the middle leaves"],"location":["whole_plant"],"pattern":["uniform"],"colour":["yellow","pale"],"progression":"Yellowing concentrated mid-plant, strongest at the base of leaflets, intensifying on newer leaves.","photo_cues":"Pale middle canopy with lower leaves less affected than expected for N; leaflet bases palest.","article":"kb-nutrients-sulfur"},{"id":"sym-mosaic-mottle","label":"Mottled mosaic or yellow streaks, distorted leaves","aka":["mosaic pattern on leaves","yellow streaks","mottled leaves","blotchy yellow pattern","virus looking leaves"],"location":["whole_plant"],"pattern":["mottled"],"colour":["yellow","pale"],"progression":"Irregular light and dark green patches, often with leaf distortion; may be on one plant only.","photo_cues":"Patchy light/dark green mosaic not following veins or leaf age; distorted, puckered blades.","article":"kb-diseases-hop-latent-viroid-and-viruses"},{"id":"sym-late-flower-fade","label":"Fan leaves yellowing late in flower while buds keep ripening","aka":["fade","autumn colours","leaves yellowing near harvest","fan leaves dying week 7","senescence"],"location":["old_growth","whole_plant"],"pattern":["uniform"],"colour":["yellow","purple","red"],"progression":"Slow, from the bottom and fan leaves first, in the last 2-3 weeks of flower; buds stay healthy and swelling.","photo_cues":"Yellow, orange or purple fan leaves in late flower with healthy, frosty buds and pistils mostly receded.","article":"kb-diagnosis-yellowing-lower-leaves"},{"id":"sym-sudden-yellowing","label":"Sudden yellowing across the plant within days","aka":["plant yellowed overnight","yellowing fast","whole plant turned yellow quickly","rapid yellowing"],"location":["whole_plant"],"pattern":["uniform"],"colour":["yellow"],"progression":"Days, not weeks; often with drooping and stalled growth.","photo_cues":"Widespread fresh yellowing plus limp leaves; check roots and reservoir in the same photo set.","article":"kb-diagnosis-root-browning-hydro"},{"id":"sym-yellow-cotyledons","label":"Seedling leaves (cotyledons) yellowing","aka":["seed leaves yellow","round leaves turning yellow","cotyledons dying","seedling first leaves yellow"],"location":["old_growth"],"pattern":["uniform"],"colour":["yellow"],"progression":"Cotyledons yellow and wither after 2-4 weeks as true leaves take over; earlier with wet medium.","photo_cues":"Two round seed leaves at the base yellowing; check whether true leaves are green and growing.","article":"kb-answers-seedling-leaves-yellow"},{"id":"sym-damage-one-side","label":"Damage only on one side of the plant or one area of the room","aka":["only one side affected","damage near the fan","one corner of the tent","problem only by the light edge"],"location":["whole_plant"],"pattern":["mottled"],"colour":[],"progression":"Localised, matches a fan, heater, vent, wall, light hotspot or a spot where spray or pests entered.","photo_cues":"Wide shot of the space showing where the damaged plants or branches sit relative to fans, lamp and vents.","article":"kb-diagnosis-how-to-diagnose-any-problem"},{"id":"sym-rust-spots-new","label":"Rust-brown spots on newer and middle leaves","aka":["brown spots on leaves","rust spots","calcium spots","brown speckles on new growth","rusty dots"],"location":["new_growth"],"pattern":["spots"],"colour":["rust","brown"],"progression":"Irregular rust to brown spots, sometimes with yellow rings, appear on recently matured leaves and spread; new growth may also distort.","photo_cues":"Irregular brown or rust spots with yellowish halo between veins on upper-middle leaves; check the underside for mites.","article":"kb-diagnosis-rust-spots"},{"id":"sym-olive-spots-old","label":"Dark olive or brown sunken spots on older leaves","aka":["dark spots on bottom leaves","bronze blotches lower leaves","phosphorus spots","olive green blotches"],"location":["old_growth"],"pattern":["spots"],"colour":["brown","bronze"],"progression":"Irregular olive-green spots on lower leaflets enlarge, look sunken and water-soaked, then merge into large dead areas.","photo_cues":"Dull dark-green leaves with irregular olive/brown sunken blotches on the oldest leaves, often with purple petioles.","article":"kb-nutrients-phosphorus"},{"id":"sym-spots-yellow-halo","label":"Round brown spots with yellow halos on lower leaves","aka":["leaf spot","brown spots yellow ring","target spots","septoria","yellow leaf spot"],"location":["old_growth"],"pattern":["spots"],"colour":["brown","yellow"],"progression":"Small spots with bright yellow halos on the lowest leaves climb the plant in wet, humid weather; spots grow and merge.","photo_cues":"Distinct roughly round tan-brown spots 2-6 mm with bright yellow halo, sometimes tiny black dots (fruiting bodies) in the centre.","article":"kb-diseases-septoria-leaf-spot"},{"id":"sym-scorched-margins-old","label":"Tan, crispy scorched edges on older leaves","aka":["burnt edges on bottom leaves","leaf edges crispy","brown leaf margins old leaves","scorched leaf edges"],"location":["old_growth","leaf_margins"],"pattern":["edges"],"colour":["brown"],"progression":"Follows marginal yellowing; dead tan tissue moves from the margin inward toward the midrib.","photo_cues":"Tan-brown dry band along the margins of lower fan leaflets with a yellow transition zone.","article":"kb-nutrients-potassium"},{"id":"sym-burnt-tips","label":"Brown, burnt leaf tips","aka":["nute burn","burnt tips","crispy tips","tip burn","brown tips on leaves","nutrient burn"],"location":["leaf_tips"],"pattern":["tips"],"colour":["brown","yellow"],"progression":"Tips of the newest mature leaves yellow then brown; the dead length grows if the cause continues.","photo_cues":"Short brown, crisp tip on many leaflets, often with a slightly curled tip and dark green leaves behind it.","article":"kb-diagnosis-brown-burnt-tips"},{"id":"sym-tan-specks-upper","label":"Small tan dead specks between veins on upper leaves","aka":["tiny brown dots upper leaves","pinpoint necrosis","speckled top leaves"],"location":["new_growth","interveinal"],"pattern":["spots"],"colour":["brown"],"progression":"Appears late on leaves already showing netted interveinal yellowing.","photo_cues":"Pinpoint tan spots scattered between veins of yellowing upper-middle leaves; nothing on the underside under a lens.","article":"kb-nutrients-manganese"},{"id":"sym-brown-speckles-old","label":"Brown or dark speckling and bronzing on older leaves","aka":["dark speckles on old leaves","brown freckles","bronze speckled lower leaves"],"location":["old_growth"],"pattern":["spots"],"colour":["brown","bronze","black"],"progression":"Fine dark speckles on older leaves, sometimes with marginal yellowing moving inward; associated with low root-zone pH.","photo_cues":"Many tiny dark-brown dots on otherwise yellowing lower leaves, no halos, no insects underneath.","article":"kb-nutrients-manganese"},{"id":"sym-random-dead-patches","label":"Irregular dead or bleached patches after spraying","aka":["spray burn","leaves burnt after spraying","foliar burn","droplet burn spots","neem burn","white patches after spray"],"location":["whole_plant"],"pattern":["spots"],"colour":["brown","white","yellow"],"progression":"Appears 1-3 days after a spray, on the leaves and leaf parts that were wet, worst where droplets pooled; does not spread afterwards.","photo_cues":"Dried-droplet shaped tan or white spots, drip-edge burns on leaf tips, damage limited to sprayed surfaces.","article":"kb-diagnosis-spots-necrosis-decision-tree"},{"id":"sym-crispy-top-leaves","label":"Crispy, papery or scorched top leaves","aka":["leaves fried at the top","light burn","heat burn","crispy upper leaves","top leaves crunchy"],"location":["new_growth"],"pattern":["uniform","edges"],"colour":["brown","yellow"],"progression":"Top leaves closest to the lamp dry out, curl and go crispy; lower canopy normal.","photo_cues":"Dry, crisp, slightly upturned top leaves with brown edges just under the fixture; IR thermometer reading on the same leaves.","article":"kb-environment-heat-light-stress"},{"id":"sym-wind-burn","label":"Dry, torn or curled leaves facing a fan","aka":["wind burn","fan burn","leaves shredded by fan","leaves clawing near the fan","windburn"],"location":["whole_plant"],"pattern":["edges","curling_down"],"colour":["brown","pale"],"progression":"Only leaves in the direct airstream; they flutter constantly, then dry at the edges, curl and tatter.","photo_cues":"Leaves on the fan side curled, thin, dry-edged or torn; the same leaves on the far side healthy.","article":"kb-environment-airflow"},{"id":"sym-lower-leaves-dying-fast","label":"Lower leaves dying and dropping quickly","aka":["bottom leaves falling off","leaves dropping","losing lower leaves fast","leaves crisping and falling"],"location":["old_growth"],"pattern":["uniform"],"colour":["yellow","brown"],"progression":"Several lower leaves yellow, die and drop within a week or two; the line of dead leaves climbs.","photo_cues":"Bare lower stem with dead leaves on the medium; note the colour pattern of the next leaves up.","article":"kb-diagnosis-yellowing-decision-tree"},{"id":"sym-water-soaked-lesions","label":"Dark, water-soaked lesions on leaves or stems","aka":["wet looking spots","greasy spots","dark soggy patches","water soaked leaves"],"location":["whole_plant"],"pattern":["spots"],"colour":["brown","black","translucent"],"progression":"Translucent, dark, wet-looking areas that enlarge and turn brown; common in humid, crowded canopies.","photo_cues":"Glassy dark patches with a soft edge, sometimes with grey fuzz in humid conditions.","article":"kb-diagnosis-spots-necrosis-decision-tree"},{"id":"sym-oedema-bumps","label":"Small raised blisters or corky bumps on leaf undersides","aka":["oedema","edema","blisters under leaves","bumps on leaves","corky spots underside"],"location":["whole_plant"],"pattern":["spots"],"colour":["pale","brown"],"progression":"Watery bumps on the underside that turn corky and tan; follows wet, cool, humid conditions with roots taking up more water than leaves lose.","photo_cues":"Raised pale or tan pimples on leaf undersides, no insects, no powder.","article":"kb-diagnosis-spots-necrosis-decision-tree"},{"id":"sym-dark-lesions-sugar-leaves","label":"Dark brown lesions on sugar leaves in flower","aka":["sugar leaves turning brown","brown spots on bud leaves","dark sugar leaf tips"],"location":["buds"],"pattern":["spots","tips"],"colour":["brown"],"progression":"Starts mid-flower on sugar leaves, followed by tip and margin browning on fan leaves.","photo_cues":"Dark brown blotches on small leaves sticking out of buds; pull one to check the bud inside for rot.","article":"kb-nutrients-potassium"},{"id":"sym-holes-in-leaves","label":"Holes chewed in leaves or ragged edges","aka":["holes in leaves","something eating my leaves","chewed leaves","bite marks","ragged leaves"],"location":["whole_plant"],"pattern":["holes"],"colour":[],"progression":"New holes appear overnight or over days; often more outdoors.","photo_cues":"Clean-edged or ragged holes; look for frass, slime trails, caterpillars or beetles at night with a torch.","article":"kb-answers-holes-in-leaves"},{"id":"sym-clawing-dark","label":"Dark green, glossy leaves with tips hooking down (the claw)","aka":["the claw","nitrogen claw","eagle claw leaves","leaves curling down at tips","dark green clawing"],"location":["whole_plant","leaf_tips"],"pattern":["clawing","curling_down"],"colour":[],"progression":"Leaves darken and the tips turn down over days; whole-plant, often after a feed increase.","photo_cues":"Very dark green, shiny leaflets with tips bent sharply down like a claw, leaves not limp.","article":"kb-diagnosis-clawing-leaves"},{"id":"sym-curl-down-wet","label":"Leaves curling down and limp while the pot is wet","aka":["droopy curled leaves","leaves curling down overwatered","whole leaf curls under","puffy droopy leaves"],"location":["whole_plant"],"pattern":["curling_down","drooping"],"colour":[],"progression":"Leaves swollen and limp, whole blade curling down from the petiole; better as the pot dries.","photo_cues":"Fat, firm-but-droopy leaves arcing down from the stem in a heavy pot; normal colour.","article":"kb-diagnosis-drooping-overwatering-vs-underwatering"},{"id":"sym-taco-leaves","label":"Leaves folding up along the midrib (taco)","aka":["taco leaves","leaves folding up","leaves cupping up","tacoing","folded leaves at the top"],"location":["new_growth"],"pattern":["curling_up"],"colour":[],"progression":"Top leaves fold upward along the midrib during the light period, worst at midday and nearest the lamp.","photo_cues":"Leaflets folded into a V, showing the paler underside, in the top canopy under the light.","article":"kb-diagnosis-taco-canoeing-leaves"},{"id":"sym-canoe-edges-up","label":"Leaf edges curling up (canoeing)","aka":["canoeing","edges rolling up","leaf margins curling up","leaves turning up at the sides"],"location":["leaf_margins"],"pattern":["curling_up"],"colour":[],"progression":"Margins turn up along the leaflet length; on top leaves with heat, light or low RH, or plant-wide with root or Ca problems.","photo_cues":"Leaflets shaped like a canoe, margins raised, sometimes with brown edges; note whether only top or whole plant.","article":"kb-diagnosis-taco-canoeing-leaves"},{"id":"sym-praying-leaves","label":"Leaves held upward, praying, healthy colour","aka":["praying leaves","leaves pointing up","leaves reaching to the light"],"location":["whole_plant"],"pattern":["curling_up"],"colour":[],"progression":"Leaves angle up during the day, relax at night; no damage.","photo_cues":"Petioles and leaflets angled toward the light, flat blades, healthy green.","article":"kb-answers-praying-leaves"},{"id":"sym-twisted-new-growth","label":"Twisted, distorted or crinkled new growth","aka":["deformed new growth","twisted leaves","mutated new leaves","crinkled top leaves","new growth growing weird"],"location":["new_growth"],"pattern":["mottled","curling_down"],"colour":[],"progression":"Newest leaves emerge twisted, cupped, narrow or crinkled; stays on new growth.","photo_cues":"Close-up of the growing tip: asymmetric, twisted, narrow leaflets; take a 30-60x photo of the shoot tip.","article":"kb-diagnosis-curling-clawing-decision-tree"},{"id":"sym-glossy-hardened-tips","label":"Glossy, stiff, curled growing tips that stop growing","aka":["shiny new growth","glassy leaves at top","tips look wet and shiny","new growth stiff and curled","broad mite damage"],"location":["new_growth"],"pattern":["curling_down","mottled"],"colour":["bronze"],"progression":"Newest leaves become glossy, leathery and downcurled, then bronze and stop expanding; can spread plant to plant.","photo_cues":"Shiny, hardened, downward-curled leaves and bronzed tips at the top of the plant; nothing visible to the eye.","article":"kb-pests-broad-russet-mites"},{"id":"sym-dying-growing-tips","label":"Growing tips dying or aborting","aka":["top died","growing tip turned brown","new growth dying","shoot tip dead","dead tops"],"location":["new_growth"],"pattern":["tips"],"colour":["brown","black"],"progression":"The apical meristem browns and dies, often after distortion; bushy side shoots follow.","photo_cues":"Brown or black dead shoot tip with distorted leaves below and new side shoots.","article":"kb-nutrients-boron"},{"id":"sym-small-narrow-new-leaves","label":"Small, narrow or cupped new leaves","aka":["tiny new leaves","narrow leaflets","leaves getting smaller","cupped new leaves","skinny new leaves"],"location":["new_growth"],"pattern":["curling_down"],"colour":["pale"],"progression":"Each new leaf smaller or narrower than the last, especially at the leaflet base.","photo_cues":"New leaves noticeably smaller and narrower at the base than the leaf below, sometimes with marginal yellowing.","article":"kb-diagnosis-curling-clawing-decision-tree"},{"id":"sym-single-blade-leaves","label":"Single-bladed, round or smooth-edged new leaves","aka":["single finger leaves","round leaves","reveg leaves","mutant leaves","leaves with no serrations"],"location":["new_growth","buds"],"pattern":["mottled"],"colour":[],"progression":"Appears weeks into flower or after harvest-and-regrow; new shoots with 1-3 smooth leaflets from the buds.","photo_cues":"Odd, roundish single-blade leaves growing out of bud sites or tips.","article":"kb-answers-single-finger-leaves-reveg"},{"id":"sym-margins-roll-under","label":"Leaf edges rolling under, leaves curling downward without darkening","aka":["edges curling down","leaves rolling under","leaf margins curl under"],"location":["leaf_margins"],"pattern":["curling_down"],"colour":[],"progression":"Margins turn under across much of the plant; may appear with wet roots, heat or early calcium or boron trouble.","photo_cues":"Leaflets with margins rolled downward, normal-to-light green, not shiny-dark like nitrogen claw.","article":"kb-diagnosis-curling-clawing-decision-tree"},{"id":"sym-droop-wet-pot","label":"Drooping while the pot is heavy and wet","aka":["overwatered","droopy and wet soil","drooping after watering","plant sad and soil wet","limp leaves wet soil"],"location":["whole_plant"],"pattern":["drooping"],"colour":[],"progression":"Droops within hours of watering and stays droopy until the pot dries; repeats each watering.","photo_cues":"Whole plant drooping, leaves firm and swollen, dark wet medium surface, heavy pot.","article":"kb-diagnosis-drooping-overwatering-vs-underwatering"},{"id":"sym-wilt-dry-pot","label":"Wilting with a light, dry pot","aka":["underwatered","thirsty plant","dry soil drooping","plant wilted dry","leaves hanging limp dry pot"],"location":["whole_plant"],"pattern":["wilting"],"colour":[],"progression":"Leaves go limp and papery, droop from the petiole; recovers within hours of watering.","photo_cues":"Limp, thin leaves hanging straight down, medium pulled away from the pot wall, very light pot.","article":"kb-diagnosis-drooping-overwatering-vs-underwatering"},{"id":"sym-wilt-moist-not-recovering","label":"Wilting even though the root zone is moist, not recovering overnight","aka":["wilting but soil is wet","drooping won't recover","plant wilting in hydro","wilting with wet roots"],"location":["whole_plant"],"pattern":["wilting"],"colour":[],"progression":"Wilts under lights, partly recovers at night at first, then stops recovering; often with yellowing.","photo_cues":"Wilted plant next to a damp pot or full reservoir; photograph the roots.","article":"kb-diagnosis-drooping-wilting-decision-tree"},{"id":"sym-sudden-collapse-hydro","label":"Sudden collapse of a hydro or aero plant within hours","aka":["plant crashed overnight","whole plant wilted in DWC","aero plants collapsed","pump failed plants wilted"],"location":["whole_plant","roots"],"pattern":["wilting"],"colour":[],"progression":"Hours. Every plant on the same system wilts together.","photo_cues":"Several plants on one system flat-wilted at once; check pump, air stone, timer and reservoir level.","article":"kb-diagnosis-drooping-wilting-decision-tree"},{"id":"sym-midday-wilt","label":"Wilting under the lights that recovers at lights-off","aka":["droops in the afternoon","wilts midday","fine in the morning droopy at noon","midday droop"],"location":["whole_plant"],"pattern":["wilting","drooping"],"colour":[],"progression":"Daily cycle: turgid at lights-on, wilting by mid-photoperiod, recovering at night.","photo_cues":"Morning and midday photos of the same plant side by side, with air temperature and RH.","article":"kb-diagnosis-drooping-wilting-decision-tree"},{"id":"sym-branch-wilt","label":"A single branch wilting or dying","aka":["one branch drooping","one stem dying","half the plant wilted","branch collapsed"],"location":["stems"],"pattern":["wilting"],"colour":[],"progression":"One branch or one side wilts while the rest stays normal.","photo_cues":"The wilted branch and its junction with the main stem; look for a kink, split, crack or brown streak inside the stem.","article":"kb-diagnosis-drooping-wilting-decision-tree"},{"id":"sym-damping-off","label":"Seedling stem pinched and collapsing at the soil line","aka":["damping off","seedling fell over","seedling stem rotted","seedling stem thin at the base","seedling died suddenly"],"location":["stems"],"pattern":["wilting"],"colour":["brown","black"],"progression":"Stem darkens and narrows at soil level, then the seedling topples; neighbours follow.","photo_cues":"Thin, dark, water-soaked stem at the soil line on a fallen seedling.","article":"kb-germination-damping-off"},{"id":"sym-clone-wilting","label":"Cuttings wilting","aka":["clones wilting","clones drooping","cuttings flopped","clones not rooting and wilting"],"location":["whole_plant"],"pattern":["wilting"],"colour":[],"progression":"Hours to days after cutting or after the dome comes off.","photo_cues":"Wilted cuttings with the dome, plug moisture and any visible root tips in the photo.","article":"kb-answers-why-are-my-clones-wilting"},{"id":"sym-droop-after-transplant","label":"Drooping or stall right after transplanting","aka":["transplant shock","droopy after repotting","stalled after up-potting","sad after transplant"],"location":["whole_plant"],"pattern":["drooping"],"colour":[],"progression":"Within 1-2 days of a transplant; mild droop for 2-5 days is normal.","photo_cues":"Plant in its new pot with the date of transplant; note the medium moisture.","article":"kb-germination-transplanting"},{"id":"sym-night-droop","label":"Leaves droop at lights-off and lift in the morning","aka":["leaves droop at night","drooping in the dark","sleeping leaves"],"location":["whole_plant"],"pattern":["drooping"],"colour":[],"progression":"Daily, in step with the light cycle; normal leaf movement.","photo_cues":"Lights-off droop, lights-on recovery; no other symptom.","article":"kb-answers-praying-leaves"},{"id":"sym-weak-stems","label":"Weak, floppy stems that can't hold the plant up","aka":["floppy stems","stems falling over","weak stalk","stem too thin","plant leaning"],"location":["stems"],"pattern":["drooping"],"colour":[],"progression":"Thin, soft stems bend under their own weight or under buds.","photo_cues":"Bending or leaning stems, internode length and the light distance in one photo.","article":"kb-answers-weak-floppy-stems"},{"id":"sym-stem-damage","label":"Kinked, split or snapped stem","aka":["broken branch","stem split","snapped stem","cracked stem","kinked stem"],"location":["stems"],"pattern":["wilting"],"colour":[],"progression":"Immediate, after training, wind, heavy buds or handling; the part above may wilt.","photo_cues":"The wound itself, whether bark is still connected, and the state of the leaves above it.","article":"kb-training-hst-supercropping"},{"id":"sym-stem-base-rot","label":"Brown, soft or sunken stem base or crown","aka":["stem rotting at the base","crown rot","brown stem at soil","soft stem near roots"],"location":["stems","roots"],"pattern":["slime"],"colour":["brown","black"],"progression":"Discoloured, sunken tissue at or below the soil line; the plant yellows and wilts from below.","photo_cues":"Lower stem and crown with bark scraped back; reddish-brown or dark sunken areas.","article":"kb-diseases-fusarium"},{"id":"sym-stem-internal-browning","label":"Brown streaks inside the stem when cut","aka":["vascular browning","brown inside the stem","stem discoloured inside"],"location":["stems"],"pattern":["mottled"],"colour":["brown"],"progression":"Found when a wilting stem is cut lengthwise; streaking runs up from the base.","photo_cues":"Lengthwise-cut stem showing brown vascular streaks beside clean white pith.","article":"kb-diseases-fusarium"},{"id":"sym-stem-cankers","label":"Lesions or grey mould on stems","aka":["stem canker","mould on stem","stem lesion","grey patch on branch"],"location":["stems"],"pattern":["spots","powder"],"colour":["grey","brown"],"progression":"Lesion girdles a branch, which then wilts above it; worst in humid flower rooms and at wounds.","photo_cues":"Tan to grey lesion on a stem, often at a wound or node, sometimes with grey fuzz.","article":"kb-diseases-botrytis-bud-rot"},{"id":"sym-brittle-stems","label":"Brittle stems that snap easily","aka":["stems break easily","brittle branches","snapping stems","stem brittle"],"location":["stems"],"pattern":["uniform"],"colour":[],"progression":"Plant-wide; often with stunting and small, low-resin flowers.","photo_cues":"Stems that snap cleanly when bent gently, on a stunted plant.","article":"kb-diseases-hop-latent-viroid-and-viruses"},{"id":"sym-purple-stems","label":"Purple or red stems and petioles","aka":["purple stems","red stems","red petioles","stems turning purple","purple leaf stems"],"location":["stems","petioles"],"pattern":["uniform"],"colour":["purple","red"],"progression":"Often from early veg; stable; may deepen with cool nights or strong light.","photo_cues":"Red-purple petioles and stems on otherwise healthy green leaves.","article":"kb-diagnosis-purple-stems-leaves"},{"id":"sym-red-petioles-yellow-lower","label":"Red-purple petioles with yellowing lower leaves","aka":["red stems and yellow leaves","purple petioles lower leaves yellow"],"location":["old_growth","petioles"],"pattern":["uniform"],"colour":["red","purple","yellow"],"progression":"Red-brown petioles appear on the worst-affected lower leaves as they yellow.","photo_cues":"Lower fan leaves yellowing with red-brown petioles; upper leaves green with green petioles.","article":"kb-nutrients-nitrogen"},{"id":"sym-purple-leaves","label":"Purple leaves, bracts or sugar leaves","aka":["purple leaves","leaves turning purple","purple buds","purpling","purple sugar leaves"],"location":["whole_plant","buds"],"pattern":["uniform"],"colour":["purple"],"progression":"Late flower or after cool nights; in purple cultivars spreads to bracts and sugar leaves.","photo_cues":"Even purple colour on leaves and bracts, tissue healthy, no spots.","article":"kb-diagnosis-purple-stems-leaves"},{"id":"sym-dark-green-leaves","label":"Very dark green, glossy leaves","aka":["leaves too dark","deep green leaves","dark shiny leaves","blue green leaves"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Days after a feed increase; often with clawing and soft, leafy growth.","photo_cues":"Unusually dark, glossy, slightly thick leaves compared with the same cultivar.","article":"kb-nutrients-nitrogen"},{"id":"sym-dark-dull-purple-blotch","label":"Dark, dull blue-green leaves with purple or bronze blotches","aka":["dull dark leaves","blue green with purple","leaves dark and dull","purple blotches on leaves"],"location":["old_growth"],"pattern":["mottled"],"colour":["purple","bronze"],"progression":"Lower leaves darken and lose shine, then purple-bronze blotches and olive spots appear; growth slows.","photo_cues":"Matte dark-green lower leaves with irregular purple-bronze areas and some olive spots.","article":"kb-nutrients-phosphorus"},{"id":"sym-bronze-leaves","label":"Bronzed, rusty-looking leaf surfaces","aka":["bronzing","leaves look bronze","rusty leaves","leaves turning copper","russet leaves"],"location":["whole_plant"],"pattern":["mottled"],"colour":["bronze","rust"],"progression":"Bronzing spreads up from lower leaves (russet mites) or from the tips (broad mites); leaf edges may curl up.","photo_cues":"Dull bronze sheen on upper leaf surfaces with edges curling up; take a 30-60x photo.","article":"kb-pests-broad-russet-mites"},{"id":"sym-dull-grey-leaves","label":"Dull, grey-green, leathery leaves","aka":["leaves look grey","dull leaves","leaves lost their shine","leathery leaves"],"location":["whole_plant"],"pattern":["uniform"],"colour":["grey"],"progression":"Plant-wide over days, often with slowed growth and burnt tips.","photo_cues":"Matte grey-green canopy with thick leaves; include runoff EC.","article":"kb-diagnosis-discolouration-decision-tree"},{"id":"sym-purple-buds","label":"Purple or dark buds in late flower","aka":["purple buds","dark buds","black buds","buds turning purple"],"location":["buds"],"pattern":["uniform"],"colour":["purple"],"progression":"Late flower, often after cooler nights; only in cultivars that carry the trait.","photo_cues":"Purple bracts and sugar leaves on healthy, frosty buds.","article":"kb-diagnosis-purple-stems-leaves"},{"id":"sym-white-powder","label":"White powdery spots that wipe off and come back","aka":["powdery mildew","white powder on leaves","PM","flour on leaves","white fuzzy spots"],"location":["whole_plant"],"pattern":["powder"],"colour":["white","grey"],"progression":"Small round white colonies on upper leaf surfaces, often older or shaded leaves first; merge and spread to buds.","photo_cues":"Talc-like circular patches on the upper side of fan leaves; wipe test photo before and after.","article":"kb-diseases-powdery-mildew"},{"id":"sym-grey-fuzz","label":"Grey, fuzzy mould","aka":["grey mould","gray mold","fuzzy grey stuff","botrytis","mouldy leaves"],"location":["whole_plant","buds"],"pattern":["powder"],"colour":["grey","brown"],"progression":"Grey-brown fuzzy growth on dead or damaged tissue, inside dense buds and at stem wounds; spreads fast in humid rooms.","photo_cues":"Dusty grey sporulating fuzz on brown dead tissue; do not shake it, spores spread.","article":"kb-diseases-botrytis-bud-rot"},{"id":"sym-white-residue","label":"White crust or residue that wipes off and stays gone","aka":["white spots after spraying","hard water spots","mineral residue","white film on leaves","dried spray residue"],"location":["whole_plant"],"pattern":["spots"],"colour":["white"],"progression":"Appears after misting, foliar feeding or spraying, in droplet shapes; doesn't grow.","photo_cues":"Crusty droplet-shaped white marks where water dried, often on top leaves.","article":"kb-diagnosis-white-powder-on-leaves"},{"id":"sym-sticky-honeydew","label":"Sticky, shiny leaves (honeydew)","aka":["sticky leaves","shiny sticky residue","leaves feel tacky","honeydew","sticky floor under plants"],"location":["whole_plant"],"pattern":["slime"],"colour":["translucent"],"progression":"Sticky gloss on leaves below a colony of sap feeders; builds over days.","photo_cues":"Glossy, wet-looking upper leaf surfaces under colonies on the leaves above; ants may be present.","article":"kb-pests-aphids"},{"id":"sym-sooty-mould","label":"Black sooty coating on leaves","aka":["black mould on leaves","sooty mould","black film","soot on leaves"],"location":["whole_plant"],"pattern":["powder"],"colour":["black"],"progression":"Grows on honeydew; follows sticky leaves by days to weeks.","photo_cues":"Black film that rubs off, on leaves already sticky.","article":"kb-diagnosis-white-grey-coatings-decision-tree"},{"id":"sym-white-cottony-clumps","label":"White cottony or waxy clumps in leaf axils and stems","aka":["white fluff on stems","cotton balls on plant","white waxy bugs","mealybugs"],"location":["stems","whole_plant"],"pattern":["powder"],"colour":["white"],"progression":"Clumps in protected spots (node junctions, under leaves) that grow slowly; honeydew follows.","photo_cues":"Waxy white clusters that, when prodded, contain oval segmented insects.","article":"kb-pests-mealybugs"},{"id":"sym-white-fuzz-medium","label":"White fuzz or threads on the medium surface","aka":["white fuzz on soil","mould on soil","white web on top of soil","white mycelium in pot"],"location":["roots"],"pattern":["powder","webbing"],"colour":["white"],"progression":"Appears on moist, organic-rich topsoil or mulch; plant healthy.","photo_cues":"Cottony white threads on the soil or mulch surface, not on the plant.","article":"kb-answers-white-fuzz-on-soil"},{"id":"sym-salt-crust-medium","label":"White crust on the medium surface or pot edges","aka":["white crust on soil","salt build up on pot","crystals on coco","white ring on pot"],"location":["roots"],"pattern":["powder"],"colour":["white"],"progression":"Builds over weeks where feed water evaporates; hard, crystalline, doesn't grow like fungus.","photo_cues":"Crusty white crystals on the medium surface, pot rim or drainage holes.","article":"kb-ph-ec-runoff-testing"},{"id":"sym-green-slime","label":"Green slime or algae on the medium, roots or in the reservoir","aka":["algae","green stuff on soil","green reservoir","slime in res","green film on rockwool"],"location":["roots"],"pattern":["slime"],"colour":[],"progression":"Grows wherever wet surfaces or solution get light; worse over weeks.","photo_cues":"Green film on rockwool, coco surface, tubing or reservoir walls; note any light leaks into the reservoir.","article":"kb-answers-algae-in-reservoir"},{"id":"sym-fuzzy-underside-yellow-top","label":"Yellow patches on top of leaves with grey-purple fuzz underneath","aka":["downy mildew","fuzz under leaves","yellow patches with mould underneath"],"location":["whole_plant"],"pattern":["spots","powder"],"colour":["yellow","grey","purple"],"progression":"Angular yellow patches bounded by veins on the upper surface, fuzzy growth below, in cool, wet, humid conditions.","photo_cues":"Upper side: vein-bounded yellow patches. Underside: grey to purplish downy growth directly beneath.","article":"kb-diagnosis-white-grey-coatings-decision-tree"},{"id":"sym-white-sparkle-trichomes","label":"White crystals or sparkles on leaves and buds that don't wipe off","aka":["white crystals","white dots on leaves","frosty leaves","glitter on leaves"],"location":["buds","whole_plant"],"pattern":["spots"],"colour":["white"],"progression":"Increases through flower on bracts and sugar leaves; normal.","photo_cues":"Under a lens: mushroom-shaped glandular heads on stalks (trichomes), not powder.","article":"kb-diagnosis-white-powder-on-leaves"},{"id":"sym-bud-rot-dead-leaf","label":"Single yellow or brown sugar leaf on an otherwise green cola","aka":["one dead leaf in bud","brown leaf in my bud","bud rot sign","dead sugar leaf pulls out easily"],"location":["buds"],"pattern":["uniform"],"colour":["yellow","brown"],"progression":"Sudden; the leaf pulls out easily and the bud tissue around it is brown and mushy inside.","photo_cues":"A lone wilted, yellow-brown sugar leaf sticking out of a dense cola; then the bud gently opened.","article":"kb-diseases-botrytis-bud-rot"},{"id":"sym-bud-brown-inside","label":"Brown, mushy or grey tissue inside buds","aka":["bud rot","rotten buds","mushy bud","grey inside bud","brown inside the cola"],"location":["buds"],"pattern":["slime","powder"],"colour":["brown","grey"],"progression":"Rot starts at the stem inside dense colas and spreads outward; can take a cola in days.","photo_cues":"Bud split open: brown slimy core or grey fuzz around the stem.","article":"kb-diseases-botrytis-bud-rot"},{"id":"sym-powder-on-buds","label":"White powder on buds and sugar leaves","aka":["powdery mildew on buds","PM on buds","white powder buds"],"location":["buds"],"pattern":["powder"],"colour":["white"],"progression":"Spreads from leaves to sugar leaves and bracts; trichomes look matted.","photo_cues":"Flat matte white patches on sugar leaves, unlike the sparkle of trichome heads.","article":"kb-diseases-powdery-mildew"},{"id":"sym-foxtails","label":"Foxtails: new calyx spires growing out of mature buds","aka":["foxtailing","buds growing towers","fox tails","spiky buds","new calyxes on top of buds"],"location":["buds"],"pattern":["mottled"],"colour":[],"progression":"Mid-to-late flower; on top colas only (stress) or evenly through the canopy (genetic).","photo_cues":"Spires of fresh white-pistilled calyxes on top of ripening buds; note whether lower buds do it too.","article":"kb-diagnosis-foxtails"},{"id":"sym-nanners","label":"Yellow banana-shaped anthers in the buds","aka":["nanners","bananas","herm","yellow bananas in buds","male parts in flower"],"location":["buds"],"pattern":["mottled"],"colour":["yellow"],"progression":"Usually mid-to-late flower; single anthers or clusters emerging from bracts.","photo_cues":"Pale-yellow curved anthers poking out among pistils, sometimes dusty with pollen.","article":"kb-diagnosis-hermaphrodites"},{"id":"sym-pollen-sacs","label":"Pollen sacs (balls) at nodes of a female plant","aka":["balls on my female","pollen sacs","male flowers on female","hermie balls"],"location":["stems","buds"],"pattern":["mottled"],"colour":[],"progression":"Clusters of round sacs on short stalks at nodes, often early flower; they open and shed pollen.","photo_cues":"Grape-like round sacs on stalks at nodes alongside pistils.","article":"kb-diagnosis-hermaphrodites"},{"id":"sym-seeds-in-buds","label":"Seeds in the buds","aka":["seeds in my buds","seedy buds","found seeds","pollinated buds"],"location":["buds"],"pattern":["mottled"],"colour":[],"progression":"Calyxes swell and split to show seeds 2-6 weeks after pollination.","photo_cues":"Swollen calyxes with seed coats showing; pattern across colas (one area or everywhere).","article":"kb-answers-why-are-there-seeds-in-my-buds"},{"id":"sym-airy-buds","label":"Airy, loose, larfy buds","aka":["larf","airy buds","fluffy buds","buds not dense","popcorn buds"],"location":["buds"],"pattern":["uniform"],"colour":[],"progression":"Seen through mid-late flower; often worst low in the canopy.","photo_cues":"Loose, open flowers with long internodes, especially on lower branches; note PPFD there.","article":"kb-answers-why-are-my-buds-airy"},{"id":"sym-pistils-brown-early","label":"Pistils browning early in flower","aka":["hairs turning brown early","pistils browning","red hairs early","orange hairs week 3"],"location":["buds"],"pattern":["uniform"],"colour":["brown","red"],"progression":"Pistils darken weeks before ripeness, often at the tops.","photo_cues":"Brown-orange pistils on young buds, especially the top colas; include the lamp distance.","article":"kb-answers-pistils-turning-brown-early"},{"id":"sym-frass-in-buds","label":"Droppings (frass), webbing or holes in buds","aka":["poop in buds","frass","caterpillar in bud","black pellets in buds","bud eaten from inside"],"location":["buds"],"pattern":["holes"],"colour":["black","brown"],"progression":"Mostly outdoors and greenhouses in flower; a browning patch of bud with pellets.","photo_cues":"Dark pellet frass on bud surface or a browned, hollowed cola; caterpillar may be inside.","article":"kb-pests-caterpillars"},{"id":"sym-flowering-delayed","label":"Flowering not starting or very slow after the flip","aka":["not flowering","still vegging after flip","no pistils after 3 weeks","won't flower"],"location":["buds"],"pattern":["uniform"],"colour":[],"progression":"No visible flowers 3+ weeks after switching to 12/12 or 13/11 (normal onset 8-14 days, slow cultivars up to 3 weeks).","photo_cues":"Top of the main stem 3 weeks after flip; a photo of the tent in the dark with the lights off.","article":"kb-environment-photoperiod-light-leaks"},{"id":"sym-buds-stall","label":"Bud swell stalls in mid-late flower","aka":["buds stopped growing","buds not fattening","flowers stalled","buds not getting bigger"],"location":["buds"],"pattern":["uniform"],"colour":[],"progression":"Buds stop gaining size for 1-2 weeks or more before expected ripeness.","photo_cues":"Same bud photographed a week apart, with feed, pH and environment logs.","article":"kb-diagnosis-bud-problems-decision-tree"},{"id":"sym-musty-smell","label":"Musty, mouldy smell in the canopy","aka":["smells like mould","musty smell","damp smell in tent","mildew smell"],"location":["buds","whole_plant"],"pattern":["odour"],"colour":[],"progression":"Noticed in flower in a humid, still room; often before visible rot.","photo_cues":"Not photographable; inspect dense colas and lower canopy.","article":"kb-diseases-botrytis-bud-rot"},{"id":"sym-roots-brown-slimy","label":"Brown, slimy roots; outer layer slides off","aka":["root rot","brown roots","slimy roots","pythium","snotty roots","roots look like wet noodles"],"location":["roots"],"pattern":["slime"],"colour":["brown"],"progression":"Starts at root tips and spreads; healthy white tips disappear; can take a DWC plant in days.","photo_cues":"Brown, mushy roots, outer sheath sloughing to leave a thin core thread; compare with any white roots.","article":"kb-diseases-root-rot-pythium"},{"id":"sym-roots-stained-firm","label":"Tan or tea-stained roots that are still firm","aka":["roots turning tan","stained roots","orange roots","roots not white but firm"],"location":["roots"],"pattern":["uniform"],"colour":["brown"],"progression":"Colour matches the nutrient solution or additive; new tips still white and fuzzy.","photo_cues":"Firm, evenly tan roots with fine root hairs and white tips; no slime, no smell.","article":"kb-diagnosis-root-browning-hydro"},{"id":"sym-root-zone-smell","label":"Rotten, sour or sewer smell from roots, medium or reservoir","aka":["reservoir smells","roots smell bad","sour soil","rotten egg smell","smells like sewage","swampy smell"],"location":["roots"],"pattern":["odour"],"colour":[],"progression":"Develops in warm, stagnant, oxygen-poor root zones; worsens fast.","photo_cues":"Not photographable; photograph the roots and water clarity.","article":"kb-diseases-root-rot-pythium"},{"id":"sym-roots-circling","label":"Thick mat of circling roots at the pot wall","aka":["root bound","rootbound","roots circling","roots out the bottom","pot full of roots"],"location":["roots"],"pattern":["uniform"],"colour":["white"],"progression":"Builds as the plant outgrows its pot; the plant then dries out within hours and stalls.","photo_cues":"Root ball out of the pot showing a dense white wall of circling roots.","article":"kb-diagnosis-root-problems-decision-tree"},{"id":"sym-no-new-root-tips","label":"No fresh white root tips","aka":["roots not growing","no new roots","roots stopped growing","roots look old"],"location":["roots"],"pattern":["uniform"],"colour":["brown"],"progression":"Root growth stops; existing roots darken.","photo_cues":"Root mass with no bright white growing tips at the margins.","article":"kb-diagnosis-root-problems-decision-tree"},{"id":"sym-stubby-root-tips","label":"Short, stubby, brown root tips","aka":["roots burnt","short roots","root tips brown and dead","stunted roots"],"location":["roots"],"pattern":["tips"],"colour":["brown"],"progression":"Root tips die back, roots thicken and branch little; plant stunts.","photo_cues":"Thick, short roots with dark dead tips and few fine laterals.","article":"kb-diagnosis-root-problems-decision-tree"},{"id":"sym-root-aphids","label":"White waxy residue and tiny insects on roots","aka":["root aphids","white powder on roots","bugs on roots","tiny bugs at the pot bottom","white waxy roots"],"location":["roots"],"pattern":["powder"],"colour":["white"],"progression":"Colonies build slowly on roots; the plant stalls, wilts and yellows without an obvious cause.","photo_cues":"Small pear-shaped insects, often olive to dark with a reddish patch, and white waxy flecks on roots at the pot edge or drain holes.","article":"kb-pests-root-aphids"},{"id":"sym-larvae-in-medium","label":"Tiny clear larvae with black heads in the medium","aka":["worms in soil","larvae in coco","maggots in pot","small white worms with black heads"],"location":["roots"],"pattern":["mottled"],"colour":["translucent","white"],"progression":"Found in the top few cm of constantly wet medium; worst in seedlings and clones.","photo_cues":"Translucent legless larvae 3-6 mm with a shiny black head, in the topsoil or on a potato slice.","article":"kb-pests-fungus-gnats"},{"id":"sym-gnats-flying","label":"Small black flies around the medium","aka":["fungus gnats","gnats","little flies in my tent","black flies around soil"],"location":["roots"],"pattern":["mottled"],"colour":["black"],"progression":"Adults appear around wet medium; numbers climb when the top stays wet.","photo_cues":"Delicate dark flies with long legs on a yellow sticky card or the medium surface.","article":"kb-pests-fungus-gnats"},{"id":"sym-reservoir-warm","label":"Reservoir or root zone water warm (above 23 °C / 73 °F)","aka":["res too hot","warm reservoir","water temperature high","reservoir temp 26"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Rises through the light period and in summer; worst in small reservoirs near lights or pumps.","photo_cues":"Thermometer reading in the reservoir at the end of the light period.","article":"kb-diagnosis-root-browning-hydro"},{"id":"sym-reservoir-cloudy","label":"Cloudy, foamy or slimy reservoir","aka":["cloudy res","foam in reservoir","biofilm","slimy tubes","milky water"],"location":["roots"],"pattern":["slime"],"colour":["white","grey"],"progression":"Develops over days; often with smell and brown roots.","photo_cues":"Clear glass sample of the solution held against light; slime on walls or tubing.","article":"kb-diagnosis-root-problems-decision-tree"},{"id":"sym-ph-rising","label":"Root-zone or reservoir pH climbing steadily","aka":["pH keeps rising","pH creeping up","runoff pH high","res pH going up"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"A few tenths per day in hydro is normal nitrate uptake; a big steady climb over weeks in containers follows alkaline water.","photo_cues":"pH log over a week.","article":"kb-ph-ec-ph-drift-hydro"},{"id":"sym-ph-falling","label":"Reservoir pH falling fast without explanation","aka":["pH dropping","pH crashing","pH keeps going down","runoff pH low"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Days; with ammonium-heavy feeds, organic additives or microbial activity on dying roots.","photo_cues":"pH log over a week and a root photo.","article":"kb-ph-ec-ph-drift-hydro"},{"id":"sym-ec-rising","label":"Reservoir EC rising as the water level drops","aka":["ppm going up","EC climbing in res","TDS rising"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Plant drinks more water than nutrients; often in hot, dry rooms or when the feed is too strong.","photo_cues":"EC and level log.","article":"kb-ph-ec-runoff-testing"},{"id":"sym-runoff-ec-high","label":"Runoff EC well above input EC","aka":["high runoff ppm","runoff EC high","salt build up","runoff higher than input"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Rises over weeks of feeding without enough runoff.","photo_cues":"Meter readings of input and runoff side by side.","article":"kb-ph-ec-runoff-testing"},{"id":"sym-runoff-ec-low","label":"Runoff EC much lower than input, or reservoir EC dropping fast","aka":["runoff ppm low","plant eating everything","EC dropping in res"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"The plant is taking up nutrients faster than they are supplied.","photo_cues":"Meter readings of input and runoff side by side.","article":"kb-ph-ec-runoff-testing"},{"id":"sym-medium-stays-wet","label":"Medium stays wet for 4+ days after watering","aka":["soil never dries","pot always wet","soil stays soggy","coco not drying"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Slow dry-back in big pots, cool rooms, dense or compacted media or with small plants.","photo_cues":"Pot weight log and a finger-depth check photo.","article":"kb-answers-how-often-to-water"},{"id":"sym-medium-dries-fast","label":"Medium dries out within a day; water runs straight through or down the sides","aka":["water runs right through","soil hydrophobic","dry pockets in pot","soil pulled away from pot"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Peat-based or over-dried media shrink and repel water; root-bound pots empty in hours.","photo_cues":"Gap between medium and pot wall; water pooling on top or rushing out of the drain.","article":"kb-answers-water-runs-through-or-pools"},{"id":"sym-white-scale-equipment","label":"White scale on pots, pumps, drippers or the meter","aka":["limescale","white deposits on equipment","clogged drippers","scale in reservoir"],"location":["roots"],"pattern":["powder"],"colour":["white"],"progression":"Builds over weeks with hard, alkaline water.","photo_cues":"Chalky deposits on reservoir walls, emitters or kettle-style scale.","article":"kb-ph-ec-water-quality"},{"id":"sym-stretchy","label":"Stretched, thin plant with long gaps between nodes","aka":["leggy","stretching","too tall and thin","long internodes","reaching for the light"],"location":["stems","whole_plant"],"pattern":["uniform"],"colour":["pale"],"progression":"Ongoing in veg under weak light; normal 1.5-3x stretch in the first 2-3 weeks after the flip.","photo_cues":"Whole-plant photo with a ruler and the light distance; internode length visible.","article":"kb-diagnosis-stretching"},{"id":"sym-excess-flower-stretch","label":"Excessive stretch after the flip (more than about 3x)","aka":["stretched too much in flower","plant doubled after flip","flower stretch out of control"],"location":["stems"],"pattern":["uniform"],"colour":[],"progression":"First 2-3 weeks after switching to 12/12.","photo_cues":"Height log from flip day, light distance and PPFD.","article":"kb-diagnosis-stretching"},{"id":"sym-leggy-seedling","label":"Leggy seedling with a long, thin stem","aka":["stretched seedling","seedling too tall","seedling falling over thin stem"],"location":["stems"],"pattern":["uniform"],"colour":["pale"],"progression":"First 1-2 weeks; the hypocotyl stretches under weak light or too much heat.","photo_cues":"Seedling side-on with the light distance.","article":"kb-answers-why-is-my-seedling-drooping"},{"id":"sym-stunted","label":"Stunted, slow growth across the plant","aka":["plant not growing","slow growth","stunted","plant stalled","barely growing"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Weeks behind expectation; may have no other visible symptom.","photo_cues":"Same plant photographed weekly with a ruler; include a sibling for comparison.","article":"kb-diagnosis-slow-growth"},{"id":"sym-one-plant-stunted","label":"One plant much smaller than identical siblings","aka":["runt","one plant behind","one clone not growing","dud plant"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Persistent through veg and flower; siblings in the same conditions are normal.","photo_cues":"The small plant next to its same-cut siblings.","article":"kb-diagnosis-slow-growth"},{"id":"sym-compact-small-leaves","label":"Short internodes, compact growth and small leaves","aka":["plant stays tiny","rosetting","bunched leaves","small leaves short nodes"],"location":["new_growth","stems"],"pattern":["uniform"],"colour":[],"progression":"New nodes stack tightly, leaves small; may follow cold, very high light or micronutrient shortage.","photo_cues":"Stack of tight nodes at the top with small leaves; compare with the leaf size lower down.","article":"kb-diagnosis-slow-growth"},{"id":"sym-seedling-stalled","label":"Seedling stalled for over a week","aka":["seedling not growing","seedling stuck","seedling not making new leaves"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Cotyledons and first true leaves present but no new growth for 7+ days.","photo_cues":"Seedling with its pot, the medium moisture and light distance.","article":"kb-germination-seedling-care"},{"id":"sym-auto-small","label":"Autoflower started flowering while still small","aka":["auto stayed tiny","autoflower small","auto flowering early and small","stunted auto"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Flowers by age at 3-5 weeks regardless; any early setback leaves it small.","photo_cues":"Plant with its pot size and age in days since sprouting.","article":"kb-answers-why-is-my-autoflower-small"},{"id":"sym-reveg-in-flower","label":"Flowering plant pushing new leafy growth instead of buds","aka":["reveg","reverting to veg","leaves growing out of buds","plant went back to veg"],"location":["buds","new_growth"],"pattern":["mottled"],"colour":[],"progression":"Weeks after an interrupted or lengthened dark period.","photo_cues":"Leafy shoots with single-blade leaves out of bud sites; photo of the dark tent.","article":"kb-answers-how-to-reveg-a-plant"},{"id":"sym-leaf-drop-sudden","label":"Sudden leaf drop over a day or two","aka":["leaves falling off suddenly","plant dropping leaves","leaves shed overnight"],"location":["whole_plant"],"pattern":["uniform"],"colour":["yellow","brown"],"progression":"Many leaves at once after a shock: cold, heat, spray, root loss or a pH crash.","photo_cues":"Dropped leaves on the medium, and the leaves still attached.","article":"kb-diagnosis-yellowing-decision-tree"},{"id":"sym-stippling","label":"Fine pale stippling (tiny white or yellow dots) on leaf tops","aka":["tiny white dots on leaves","speckled leaves","stippling","pinprick dots","leaves look dusty with dots"],"location":["whole_plant"],"pattern":["stippling"],"colour":["white","yellow","pale"],"progression":"Dots multiply until the leaf looks pale and dusty; hot, dry rooms speed it up; spreads plant to plant.","photo_cues":"Clusters of pinprick pale dots on upper surfaces; underside at 10-20x shows moving mites or eggs.","article":"kb-pests-spider-mites"},{"id":"sym-webbing","label":"Fine silk webbing on leaves, buds or tips","aka":["webs on my plant","spider webs on buds","webbing","silk on leaves"],"location":["whole_plant","buds"],"pattern":["webbing"],"colour":["white"],"progression":"Appears once mite numbers are high, starting at tips and between leaves.","photo_cues":"Fine strands with moving dots between leaves or over bud tips.","article":"kb-pests-spider-mites"},{"id":"sym-moving-dots-underside","label":"Tiny moving dots under the leaves","aka":["tiny bugs under leaves","moving specks","mites under leaves","little red dots moving"],"location":["whole_plant"],"pattern":["stippling"],"colour":["pale","red"],"progression":"Found on scouting; numbers can double in a few days when hot and dry.","photo_cues":"10-20x photo of the leaf underside: eight-legged mites, often with two dark spots, and round eggs.","article":"kb-pests-spider-mites"},{"id":"sym-silvering","label":"Silvery streaks or patches dotted with black specks","aka":["silver leaves","silvery scars","thrips damage","shiny streaks with black dots"],"location":["whole_plant"],"pattern":["mottled","spots"],"colour":["white","grey","black"],"progression":"Scars spread over upper leaf surfaces; leaves look bleached and patchy.","photo_cues":"Silvery-white scraped patches with tiny black faecal dots; slender insects under a lens.","article":"kb-pests-thrips"},{"id":"sym-aphid-clusters","label":"Clusters of soft, pear-shaped insects on stems or leaf undersides","aka":["aphids","green bugs on plant","little bugs on stems","clusters of insects under leaves"],"location":["whole_plant","stems"],"pattern":["mottled"],"colour":[],"progression":"Colonies grow fast on new growth and undersides; white shed skins and honeydew follow.","photo_cues":"Groups of soft-bodied insects with tailpipes (cornicles), white cast skins nearby.","article":"kb-pests-aphids"},{"id":"sym-white-cast-skins","label":"White flakes (shed insect skins) on leaves","aka":["white flakes on leaves","dandruff on leaves","shed skins"],"location":["whole_plant"],"pattern":["spots"],"colour":["white"],"progression":"Accumulates below aphid colonies.","photo_cues":"Papery white insect-shaped flakes; look at the leaves directly above.","article":"kb-pests-aphids"},{"id":"sym-whiteflies","label":"Tiny white flies that rise when the plant is shaken","aka":["whiteflies","white flies","little white moths","white bugs flying"],"location":["whole_plant"],"pattern":["mottled"],"colour":["white"],"progression":"Numbers build on leaf undersides; honeydew and sooty mould follow.","photo_cues":"Small white wedge-shaped flies under leaves, flat oval nymphs.","article":"kb-pests-whiteflies"},{"id":"sym-caterpillars-visible","label":"Caterpillars on leaves or buds","aka":["caterpillars","worms on my plant","green worm","budworms"],"location":["whole_plant","buds"],"pattern":["holes"],"colour":[],"progression":"Outdoors and greenhouses; feeding damage appears overnight.","photo_cues":"The caterpillar itself, frass and the damaged leaf or bud.","article":"kb-pests-caterpillars"},{"id":"sym-ants","label":"Ants on the plant","aka":["ants on my plant","ants on stems","ants in the pot"],"location":["stems","whole_plant"],"pattern":["mottled"],"colour":["black"],"progression":"Ants farming sap feeders for honeydew.","photo_cues":"Ants moving up stems toward colonies under leaves.","article":"kb-pests-aphids"},{"id":"sym-leaf-trails","label":"Winding pale trails in leaves","aka":["leaf miner trails","squiggly lines on leaves","tunnels in leaves","snake trails on leaves"],"location":["whole_plant"],"pattern":["mottled"],"colour":["white","pale"],"progression":"Serpentine tunnels lengthen and widen as the larva feeds inside the leaf.","photo_cues":"Pale winding mines with a dark line of frass inside and a larva at the wide end.","article":"kb-diagnosis-spots-necrosis-decision-tree"},{"id":"sym-purple-veins","label":"Purple or red veins, mostly on leaf undersides","aka":["purple veins","red veins under leaves","veins turning purple","purple leaf veins"],"location":["veins","old_growth"],"pattern":["uniform"],"colour":["purple","red"],"progression":"Appears on older leaves first, often after cool nights; stable in purple cultivars.","photo_cues":"Underside of a lower leaf with purple-red veins on a green blade; note any olive spots on top.","article":"kb-diagnosis-discolouration-decision-tree"},{"id":"sym-pink-bud-rot","label":"Pinkish-white mould inside buds","aka":["pink mould in buds","pink fuzz in bud","salmon coloured rot","white pink mold"],"location":["buds"],"pattern":["powder","slime"],"colour":["white","red"],"progression":"Develops inside dense buds in humid conditions; tissue browns underneath.","photo_cues":"Bud split open showing pinkish-white cottony growth rather than grey dusty spores.","article":"kb-diseases-fusarium"},{"id":"sym-bud-tips-burnt","label":"Brown, crispy bracts or bud tips on the top colas","aka":["burnt bud tips","crispy buds at the top","top buds fried","brown bracts under the light"],"location":["buds"],"pattern":["tips"],"colour":["brown","white"],"progression":"Only the colas nearest the lamp; follows a light raise or heat event.","photo_cues":"Top cola tips brown and dry while lower buds stay green; include the light distance.","article":"kb-diagnosis-bud-problems-decision-tree"},{"id":"sym-thrips-frass","label":"Tiny black specks on leaf surfaces","aka":["black dots on leaves","tiny black specks","black flecks on leaves","pepper spots"],"location":["whole_plant"],"pattern":["spots"],"colour":["black"],"progression":"Accumulates on scarred, silvery areas; does not wipe into a smear like soot.","photo_cues":"10x photo of black faecal dots on pale, scraped patches.","article":"kb-pests-thrips"},{"id":"sym-plant-not-drinking","label":"Plant stopped drinking; pot or reservoir level barely drops","aka":["plant not drinking","not using water","pot still heavy days later","reservoir level not dropping"],"location":["roots","whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Water use falls over days for a plant that used to drink well.","photo_cues":"Watering or reservoir-level log; root photo.","article":"kb-diagnosis-root-problems-decision-tree"},{"id":"sym-condensation","label":"Condensation or wet leaves at lights-off","aka":["water droplets on leaves at night","condensation in tent","tent walls wet","dew on plants"],"location":["whole_plant"],"pattern":["uniform"],"colour":[],"progression":"Each lights-off as temperature drops below the dew point.","photo_cues":"Droplets on leaves or tent walls shortly after lights-off; RH log.","article":"kb-environment-humidity-by-stage"},{"id":"sym-uneven-drip-wetting","label":"Some pots dry while others on the same line stay wet","aka":["drippers clogged","uneven watering on drip","one pot not getting water","emitter blocked"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Develops as emitters clog with scale, biofilm or particles.","photo_cues":"Emitter output into cups for one cycle, side by side.","article":"kb-systems-drain-to-waste-crop-steering"},{"id":"sym-reservoir-cold","label":"Reservoir or root zone cold (below 16 °C / 61 °F)","aka":["res too cold","cold water in reservoir","cold floor pots","water temperature low"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Lowest at the end of the dark period and in winter rooms with pots on concrete.","photo_cues":"Thermometer in the reservoir or root zone at lights-on.","article":"kb-environment-temperature-by-stage"},{"id":"sym-seed-shell-stuck","label":"Seed shell stuck on the seedling's first leaves","aka":["helmet head","seed shell stuck","cotyledons trapped in seed coat","seedling can't shed its shell"],"location":["new_growth"],"pattern":["mottled"],"colour":[],"progression":"Right after emergence; the cotyledons can't open.","photo_cues":"Seedling with the seed coat clamped over the cotyledons.","article":"kb-answers-seed-shell-stuck-on-seedling"},{"id":"sym-yellow-tips-lower","label":"Yellow tips on lower fan leaves moving down the leaflet","aka":["lower leaf tips yellow","yellow tips on bottom leaves","tips of old leaves yellowing"],"location":["old_growth","leaf_tips"],"pattern":["tips"],"colour":["yellow"],"progression":"Starts at the tips of lower fan leaves and spreads inward and upward.","photo_cues":"Lower fan leaflets yellowing from the tip, not from the margin teeth, upper leaves green.","article":"kb-diagnosis-yellowing-decision-tree"},{"id":"sym-new-growth-limp","label":"Newest leaves limp while older leaves stay firm","aka":["top leaves floppy","new growth wilting","new leaves droopy","limp tops"],"location":["new_growth"],"pattern":["drooping"],"colour":[],"progression":"Days; the newest leaves lose turgor and may distort.","photo_cues":"Close-up of the top two nodes with soft, drooping leaves above firm older leaves.","article":"kb-diagnosis-drooping-wilting-decision-tree"},{"id":"sym-water-pools-slow-drain","label":"Water pools on the surface and drains slowly","aka":["water sits on top","soil compacted","slow draining pot","puddles on soil"],"location":["roots"],"pattern":["uniform"],"colour":[],"progression":"Worsens as the medium compacts or as roots fill and fines clog the drainage.","photo_cues":"Standing water on the medium a minute after watering; drainage holes.","article":"kb-answers-water-runs-through-or-pools"},{"id":"sym-tiny-white-jumpers-soil","label":"Tiny white insects jumping on the medium surface","aka":["small white bugs in soil","white jumping bugs","springtails","tiny white bugs in water tray"],"location":["roots"],"pattern":["mottled"],"colour":["white"],"progression":"Seen when watering wet organic media; plant healthy.","photo_cues":"Tiny white or grey wingless insects that spring away when disturbed, in the saucer or on the surface.","article":"kb-answers-small-white-bugs-in-soil"}],"causes":[{"id":"cause-n-deficiency","label":"Nitrogen deficiency","kind":"nutrient","mobility":"mobile","base_rate":"very_common","symptoms":{"sym-yellow-tips-lower":"typical","sym-yellow-lower-leaves":"hallmark","sym-whole-plant-pale":"typical","sym-red-petioles-yellow-lower":"typical","sym-lower-leaves-dying-fast":"typical","sym-stunted":"possible","sym-runoff-ec-low":"typical","sym-buds-stall":"possible","sym-yellow-cotyledons":"possible"},"contexts":{"stage":{"late_flower":"lower","seedling":"lower"},"medium":{"coco":"higher","water":"higher","living_soil":"lower"},"feed_strength":{"none":"higher","light":"higher","heavy":"lower"},"where_first":{"old_growth":"higher","new_growth":"lower","top_near_light":"lower"},"readings":{"runoff_ec_low":"higher","ec_low":"higher","runoff_ec_high":"lower","ph_out_of_range":"lower"}},"rule_out_first":["cause-overwatering","cause-root-rot-pythium","cause-ph-low-lockout","cause-cold-root-zone","cause-root-aphids","cause-normal-senescence"],"distinguishing_questions":["q-stage","q-where-first","q-feed-strength","q-ec-runoff","q-ph-runoff","q-pot-weight","q-root-colour"],"tests":["test-runoff-ec","test-ph-input-runoff","test-root-inspection","test-response-to-fix","test-leaf-tissue"],"fix":"Fix roots, watering and pH first. If N is genuinely short, raise feed N by about 10-20% (not double): mineral feeds around 150-200 mg/L N in veg and early flower; one DWC flowering trial predicted a yield optimum near 194 mg/L. Coco/hydro: raise base feed EC by ~0.2 mS/cm. Soil: liquid feed at label rate. Living soil: top-dress a fast organic N source and allow 1-2 weeks. Late flower: a gradual fade is the planned N taper, not a fault.","confirm":"Yellowing stops climbing within 5-7 days and new leaves emerge mid-green; already-yellow leaves do not recover. Runoff EC climbs back toward input.","urgency":"medium","house_position":false,"article":"kb-nutrients-nitrogen","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Bevan L, Jones M, Zheng Y. 2021. Optimisation of nitrogen, phosphorus, and potassium for soilless production of Cannabis sativa in the flowering stage using response surface analysis. Frontiers in Plant Science 12:764103. https://doi.org/10.3389/fpls.2021.764103","Saloner A, Bernstein N. 2021. Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis (Cannabis sativa L.). Industrial Crops and Products 167:113516. https://doi.org/10.1016/j.indcrop.2021.113516"]},{"id":"cause-p-deficiency","label":"Phosphorus deficiency","kind":"nutrient","mobility":"mobile","base_rate":"uncommon","symptoms":{"sym-purple-veins":"typical","sym-olive-spots-old":"hallmark","sym-dark-dull-purple-blotch":"typical","sym-stunted":"typical","sym-purple-stems":"possible","sym-lower-leaves-dying-fast":"possible","sym-canoe-edges-up":"rare"},"contexts":{"medium":{"water":"higher","coco":"higher","living_soil":"lower"},"readings":{"night_cold":"higher","temp_low":"higher","res_temp_low":"higher","ph_high":"higher","runoff_ec_low":"higher"},"feed_strength":{"none":"higher","light":"higher"},"cultivar_purple":{"known_purple":"lower"}},"rule_out_first":["cause-cold-stress","cause-cold-root-zone","cause-ph-high-p-lockout","cause-genetic-anthocyanin","cause-septoria"],"distinguishing_questions":["q-night-temp","q-cultivar-purple","q-ph-runoff","q-feed-strength","q-where-first"],"tests":["test-ph-input-runoff","test-runoff-ec","test-leaf-tissue","test-response-to-fix"],"fix":"Warm the root zone to 18-22 °C (64-72 °F) and nights above ~15 °C (59 °F) first; cold blocks P uptake. Correct pH (soilless 5.5-6.5, soil 6.0-7.0). If genuinely short, supply about 30-60 mg/L P; controlled cannabis trials found no yield or cannabinoid gain above roughly 25-60 mg/L, so skip 'bloom boosters'. Soil: a balanced liquid feed; living soil: a slow P amendment acts in weeks.","confirm":"No new olive spots on leaves that open after the fix, within 7-10 days; growth rate picks up. Spotted leaves stay damaged.","urgency":"medium","house_position":false,"article":"kb-nutrients-phosphorus","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Shiponi S, Bernstein N. 2021. The highs and lows of P supply in medical cannabis: effects on cannabinoids, the ionome, and morpho-physiology. Frontiers in Plant Science 12:657323. https://doi.org/10.3389/fpls.2021.657323","Westmoreland FM, Bugbee B. 2022. Sustainable cannabis nutrition: elevated root-zone phosphorus significantly increases leachate P and does not improve yield or quality. Frontiers in Plant Science 13:1015652. https://doi.org/10.3389/fpls.2022.1015652"]},{"id":"cause-k-deficiency","label":"Potassium deficiency","kind":"nutrient","mobility":"mobile","base_rate":"uncommon","symptoms":{"sym-yellow-tips-lower":"possible","sym-yellow-margins-old":"hallmark","sym-scorched-margins-old":"hallmark","sym-dark-lesions-sugar-leaves":"typical","sym-burnt-tips":"possible","sym-weak-stems":"possible","sym-buds-stall":"possible"},"contexts":{"stage":{"early_flower":"higher","late_flower":"higher"},"medium":{"water":"higher","coco":"lower"},"readings":{"runoff_ec_low":"higher","runoff_ec_high":"lower","sodium_high":"higher"},"water_source":{"softened":"higher"},"calmag":{"yes":"higher"}},"rule_out_first":["cause-salt-buildup","cause-overfeeding","cause-sodium-toxicity","cause-b-toxicity","cause-mn-toxicity","cause-wind-burn"],"distinguishing_questions":["q-where-first","q-ec-runoff","q-water-source","q-calmag","q-stage"],"tests":["test-runoff-ec","test-water-report","test-leaf-tissue","test-response-to-fix"],"fix":"Check runoff EC first: salt burn looks the same. If K is genuinely short, feed about 175-250 mg/L K (potassium sulfate, potassium nitrate or MKP) at a normal EC. A flowering DWC trial saw no yield response anywhere from 60 to 340 mg/L, so more is not better. Cut heavy Cal-Mag or sodium-rich water that competes with K.","confirm":"Margin scorch stops advancing up the plant within 7 days; new leaves open with clean margins.","urgency":"medium","house_position":false,"article":"kb-nutrients-potassium","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Bevan L, Jones M, Zheng Y. 2021. Optimisation of nitrogen, phosphorus, and potassium for soilless production of Cannabis sativa in the flowering stage using response surface analysis. Frontiers in Plant Science 12:764103. https://doi.org/10.3389/fpls.2021.764103","Saloner A, Bernstein N. 2022. Effect of potassium (K) supply on cannabinoids, terpenoids and plant function in medical cannabis. Agronomy 12(5):1242. https://doi.org/10.3390/agronomy12051242"]},{"id":"cause-ca-deficiency","label":"Calcium deficiency (often a delivery problem)","kind":"nutrient","mobility":"immobile","base_rate":"common","symptoms":{"sym-rust-spots-new":"hallmark","sym-twisted-new-growth":"typical","sym-small-narrow-new-leaves":"typical","sym-dying-growing-tips":"possible","sym-canoe-edges-up":"possible","sym-yellow-new-margins":"possible","sym-margins-roll-under":"possible"},"contexts":{"medium":{"coco":"higher","water":"higher","living_soil":"lower"},"water_source":{"ro":"higher","rain":"higher","well":"lower"},"rh":{"very_high":"higher","high":"higher"},"readings":{"ph_low":"higher","vpd_low":"higher","rh_high":"higher"},"magnifier_underside":{"glassy_specks":"lower","moving_dots":"lower","slender_insects":"lower"},"calmag":{"yes":"lower"}},"rule_out_first":["cause-broad-mites","cause-spider-mites","cause-ph-low-lockout","cause-low-vpd-high-rh","cause-coco-unbuffered","cause-root-rot-pythium"],"distinguishing_questions":["q-magnifier-underside","q-water-source","q-medium","q-rh","q-ph-runoff","q-calmag"],"tests":["test-magnifier","test-ph-input-runoff","test-water-report","test-hygrometer-check","test-response-to-fix"],"fix":"Rule out mites with a 30-60x lens first. Then fix delivery: leaf VPD 0.8-1.5 kPa (lights-on RH not stuck high), airflow under the canopy, root-zone pH not below ~5.8 in coco. If supply is short (RO water, unbuffered coco), bring Ca to about 150-200 mg/L with calcium nitrate or a Cal-Mag at label rate. LEDs do not create a Cal-Mag need; that is a myth.","confirm":"Leaves that open 7-10 days after the fix are flat and spot-free; old spots stay.","urgency":"medium","house_position":true,"article":"kb-nutrients-calcium","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9","Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6"]},{"id":"cause-mg-deficiency","label":"Magnesium deficiency","kind":"nutrient","mobility":"mobile","base_rate":"common","symptoms":{"sym-interveinal-yellow-old":"hallmark","sym-yellow-lower-leaves":"possible","sym-lower-leaves-dying-fast":"possible","sym-rust-spots-new":"rare"},"contexts":{"stage":{"early_flower":"higher","late_flower":"higher"},"medium":{"coco":"higher"},"water_source":{"ro":"higher","rain":"higher"},"readings":{"ph_low":"higher"},"calmag":{"yes":"lower"},"where_first":{"old_growth":"higher","new_growth":"lower","top_near_light":"lower"}},"rule_out_first":["cause-ph-low-lockout","cause-k-excess","cause-calcium-excess","cause-normal-senescence","cause-light-bleaching"],"distinguishing_questions":["q-where-first","q-ph-runoff","q-water-source","q-calmag","q-stage"],"tests":["test-ph-input-runoff","test-water-report","test-leaf-tissue","test-response-to-fix"],"fix":"Check root-zone pH (Mg uptake falls at low pH) and whether heavy K or Ca is crowding it out. If short, bring Mg to about 40-70 mg/L with magnesium sulfate (roughly 0.4-0.5 g/L of the heptahydrate adds ~40-50 mg/L Mg) or magnesium nitrate. A 1-2 g/L magnesium sulfate foliar spray greens veg leaves faster; never spray buds.","confirm":"Interveinal yellowing stops climbing in 5-7 days; leaves above the damage stay green.","urgency":"low","house_position":false,"article":"kb-nutrients-magnesium","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Morad D, Bernstein N. 2023. Response of medical cannabis to magnesium (Mg) supply at the vegetative growth phase. Plants 12(14):2676. https://doi.org/10.3390/plants12142676"]},{"id":"cause-s-deficiency","label":"Sulfur deficiency","kind":"nutrient","mobility":"partly_mobile","base_rate":"rare","symptoms":{"sym-yellow-new-growth":"hallmark","sym-yellow-middle-leaves":"hallmark","sym-whole-plant-pale":"typical","sym-interveinal-yellow-old":"rare"},"contexts":{"medium":{"water":"higher","living_soil":"lower"},"feed_strength":{"none":"higher"},"readings":{"ph_out_of_range":"lower"}},"rule_out_first":["cause-n-deficiency","cause-fe-deficiency","cause-light-bleaching","cause-ph-high-lockout"],"distinguishing_questions":["q-where-first","q-feed-strength","q-ph-runoff","q-top-only"],"tests":["test-leaf-tissue","test-ppfd-meter","test-response-to-fix"],"fix":"Rare unless a feed is built only from nitrates and chlorides. Supply about 50-120 mg/L S as sulfate, e.g. via magnesium sulfate or potassium sulfate at normal rates.","confirm":"New leaves emerge green within 7-10 days.","urgency":"low","house_position":false,"article":"kb-nutrients-sulfur","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-fe-deficiency","label":"Iron deficiency (usually high pH)","kind":"nutrient","mobility":"immobile","base_rate":"uncommon","symptoms":{"sym-interveinal-yellow-new":"hallmark","sym-white-new-growth":"typical","sym-yellow-new-growth":"possible"},"contexts":{"readings":{"ph_high":"higher","alkalinity_high":"higher","res_temp_low":"higher","ph_low":"lower"},"water_source":{"well":"higher"},"top_only":{"yes":"lower"},"where_first":{"new_growth":"higher","old_growth":"lower"}},"rule_out_first":["cause-ph-high-lockout","cause-high-alkalinity-water","cause-light-bleaching","cause-overwatering","cause-mn-deficiency"],"distinguishing_questions":["q-ph-runoff","q-top-only","q-alkalinity","q-where-first"],"tests":["test-ph-input-runoff","test-water-report","test-ppfd-meter","test-response-to-fix"],"fix":"Bring root-zone pH into range first: soilless 5.5-6.2, soil 6.0-6.8. Neutralise alkaline water with acid. Supply 1.5-3 mg/L Fe as a chelate matched to pH: EDTA to about pH 6.5, DTPA to about 7.5, EDDHA to about 9. A foliar iron chelate spray (veg only) greens leaves in days.","confirm":"The next new leaves open green within 5-10 days; the whitened leaves re-green partly or not at all.","urgency":"low","house_position":false,"article":"kb-nutrients-iron","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-mn-deficiency","label":"Manganese deficiency","kind":"nutrient","mobility":"immobile","base_rate":"uncommon","symptoms":{"sym-netted-yellow-upper-spots":"hallmark","sym-tan-specks-upper":"typical","sym-interveinal-yellow-new":"possible"},"contexts":{"readings":{"ph_high":"higher","alkalinity_high":"higher","ph_low":"lower"},"medium":{"living_soil":"higher","soil":"higher"}},"rule_out_first":["cause-ph-high-lockout","cause-fe-deficiency","cause-spider-mites"],"distinguishing_questions":["q-ph-runoff","q-magnifier-underside","q-where-first"],"tests":["test-ph-input-runoff","test-magnifier","test-leaf-tissue"],"fix":"Correct high pH and alkalinity first. Supply about 0.3-0.8 mg/L Mn (manganese sulfate or chelate); avoid large iron chelate doses that compete with Mn.","confirm":"New upper leaves lose the netted pattern within 7-10 days.","urgency":"low","house_position":false,"article":"kb-nutrients-manganese","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-zn-deficiency","label":"Zinc deficiency","kind":"nutrient","mobility":"immobile","base_rate":"rare","symptoms":{"sym-yellow-new-margins":"hallmark","sym-small-narrow-new-leaves":"typical","sym-compact-small-leaves":"possible","sym-interveinal-yellow-new":"possible"},"contexts":{"readings":{"ph_high":"higher","alkalinity_high":"higher"},"feed_strength":{"heavy":"higher"}},"rule_out_first":["cause-ph-high-lockout","cause-p-excess","cause-broad-mites","cause-heat-stress","cause-hlvd"],"distinguishing_questions":["q-ph-runoff","q-magnifier-underside","q-feed-strength","q-spread"],"tests":["test-ph-input-runoff","test-magnifier","test-leaf-tissue"],"fix":"Lower high pH, stop excess phosphorus 'boosters' (high P ties up Zn), then supply about 0.1-0.5 mg/L Zn as zinc sulfate or chelate.","confirm":"New leaves reach normal size with clean margins in 7-14 days.","urgency":"low","house_position":false,"article":"kb-nutrients-zinc","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-b-deficiency","label":"Boron deficiency","kind":"nutrient","mobility":"immobile","base_rate":"rare","symptoms":{"sym-new-growth-limp":"possible","sym-dying-growing-tips":"hallmark","sym-twisted-new-growth":"typical","sym-small-narrow-new-leaves":"typical","sym-wilt-moist-not-recovering":"possible","sym-stubby-root-tips":"possible"},"contexts":{"water_source":{"ro":"higher"},"readings":{"ph_high":"higher","vpd_low":"higher"},"magnifier_underside":{"glassy_specks":"lower"}},"rule_out_first":["cause-broad-mites","cause-ca-deficiency","cause-root-rot-pythium","cause-heat-stress"],"distinguishing_questions":["q-magnifier-underside","q-water-source","q-root-colour","q-ph-runoff"],"tests":["test-magnifier","test-root-inspection","test-leaf-tissue"],"fix":"Rule out broad mites first. Supply about 0.2-0.5 mg/L B (boric acid ~1.1-2.9 mg/L, or a complete micro mix). The gap between enough and too much is narrow: never add B 'just in case' on top of a complete feed.","confirm":"New shoots grow normally from the tip or from side buds within 10-14 days.","urgency":"medium","house_position":false,"article":"kb-nutrients-boron","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-cu-deficiency","label":"Copper deficiency","kind":"nutrient","mobility":"immobile","base_rate":"rare","symptoms":{"sym-new-growth-limp":"typical","sym-small-narrow-new-leaves":"typical","sym-twisted-new-growth":"possible","sym-margins-roll-under":"typical","sym-midday-wilt":"possible"},"contexts":{"water_source":{"ro":"higher"},"medium":{"water":"higher"}},"rule_out_first":["cause-b-deficiency","cause-ca-deficiency","cause-broad-mites","cause-root-rot-pythium"],"distinguishing_questions":["q-magnifier-underside","q-water-source","q-root-colour"],"tests":["test-magnifier","test-leaf-tissue"],"fix":"Very rare with a complete micro mix. Supply about 0.03-0.1 mg/L Cu; do not overshoot (excess Cu damages roots).","confirm":"New leaves regain size and turgor in 10-14 days.","urgency":"low","house_position":false,"article":"kb-nutrients-copper","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-mo-deficiency","label":"Molybdenum deficiency","kind":"nutrient","mobility":"mobile","base_rate":"rare","symptoms":{"sym-yellow-middle-leaves":"typical","sym-yellow-lower-leaves":"rare","sym-scorched-margins-old":"rare"},"contexts":{"readings":{"ph_low":"higher"},"water_source":{"ro":"higher"}},"rule_out_first":["cause-n-deficiency","cause-ph-low-lockout"],"distinguishing_questions":["q-ph-runoff","q-water-source"],"tests":["test-leaf-tissue","test-ph-input-runoff"],"fix":"Almost never the answer: cannabis grown 9 weeks without Mo showed no visible symptoms. Correct low pH (Mo availability falls as pH drops); supply about 0.01-0.05 mg/L Mo via a complete micro mix.","confirm":"Pale middle leaves stop spreading after pH correction.","urgency":"low","house_position":false,"article":"kb-nutrients-molybdenum","sources":["Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-ni-deficiency","label":"Nickel deficiency","kind":"nutrient","mobility":"mobile","base_rate":"rare","symptoms":{"sym-burnt-tips":"typical","sym-yellow-new-margins":"rare"},"contexts":{"water_source":{"ro":"higher"}},"rule_out_first":["cause-overfeeding","cause-zn-deficiency"],"distinguishing_questions":["q-water-source","q-feed-strength"],"tests":["test-leaf-tissue"],"fix":"No published cannabis case. Only conceivable on very pure RO systems fed urea; do not add nickel otherwise (excess is toxic and cannabis accumulates metals).","confirm":"Not applicable in practice; look for another cause.","urgency":"low","house_position":false,"article":"kb-nutrients-nickel","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-underfeeding","label":"General underfeeding (whole feed too weak)","kind":"nutrient","mobility":"mixed","base_rate":"common","symptoms":{"sym-whole-plant-pale":"hallmark","sym-yellow-lower-leaves":"typical","sym-stunted":"typical","sym-runoff-ec-low":"hallmark","sym-airy-buds":"possible","sym-weak-stems":"possible"},"contexts":{"feed_strength":{"none":"higher","light":"higher","heavy":"lower"},"medium":{"coco":"higher","water":"higher","rockwool":"higher","living_soil":"lower"},"stage":{"seedling":"lower"},"readings":{"ec_low":"higher","runoff_ec_low":"higher","ec_high":"lower"}},"rule_out_first":["cause-overwatering","cause-ph-high-lockout","cause-ph-low-lockout","cause-root-rot-pythium","cause-low-light"],"distinguishing_questions":["q-feed-strength","q-ec-input","q-ec-runoff","q-medium"],"tests":["test-runoff-ec","test-ph-input-runoff"],"fix":"Raise the whole feed in steps of about 0.2-0.3 mS/cm toward the stage target (veg 1.2-1.8, flower 1.6-2.2 mS/cm in coco and hydro). Stop any 'flush': plain water for weeks starves the plant, and pre-harvest flushing is a myth that costs yield.","confirm":"Colour deepens and growth speeds up within a week; runoff EC tracks input.","urgency":"medium","house_position":true,"article":"kb-nutrients-feed-by-stage","sources":["Bevan L, Jones M, Zheng Y. 2021. Optimisation of nitrogen, phosphorus, and potassium for soilless production of Cannabis sativa in the flowering stage using response surface analysis. Frontiers in Plant Science 12:764103. https://doi.org/10.3389/fpls.2021.764103","Caplan D, Dixon M, Zheng Y. 2017. Optimal rate of organic fertilizer during the vegetative-stage for cannabis grown in two coir-based substrates. HortScience 52(9):1307-1312. https://doi.org/10.21273/HORTSCI11903-17","GenetixBay house position: pre-harvest flushing is a myth (see kb-harvest-cure-flush-debate for the controlled studies)."]},{"id":"cause-coco-unbuffered","label":"Unbuffered or new coco pulling calcium and magnesium","kind":"root_zone","base_rate":"common","symptoms":{"sym-rust-spots-new":"typical","sym-interveinal-yellow-old":"typical","sym-twisted-new-growth":"possible","sym-yellow-margins-old":"rare"},"contexts":{"medium":{"coco":"higher","soil":"lower","living_soil":"lower","water":"lower","rockwool":"lower"},"stage":{"seedling":"higher","veg":"higher"},"calmag":{"yes":"lower"},"recent_changes":{"transplant":"higher"}},"rule_out_first":["cause-ph-low-lockout","cause-broad-mites"],"distinguishing_questions":["q-medium","q-calmag","q-water-source","q-recent-changes"],"tests":["test-runoff-ec","test-ph-input-runoff","test-water-report"],"fix":"Feed with Ca and Mg on board: calcium nitrate and magnesium sulfate, or a Cal-Mag, bringing the feed to about 150-200 mg/L Ca and 40-60 mg/L Mg, at pH 5.8-6.2. For the next batch, rinse and buffer coco by soaking it in a calcium (and magnesium) nitrate solution before planting.","confirm":"New leaves clean within 7-10 days; runoff Ca/Mg symptoms stop spreading.","urgency":"medium","house_position":false,"article":"kb-ph-ec-buffering-coco","sources":["Minnesota Pollution Control Agency. Chemical and physical properties of coir. https://stormwater.pca.state.mn.us/Chemical_and_physical_properties_of_coir","Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6"]},{"id":"cause-n-toxicity","label":"Too much nitrogen","kind":"toxicity","base_rate":"common","symptoms":{"sym-clawing-dark":"hallmark","sym-dark-green-leaves":"hallmark","sym-weak-stems":"possible","sym-burnt-tips":"possible","sym-airy-buds":"rare"},"contexts":{"feed_strength":{"heavy":"higher","none":"lower","light":"lower"},"recent_changes":{"feed_increase":"higher","new_feed":"higher"},"stage":{"seedling":"higher","early_flower":"higher"},"pot_weight":{"heavy":"lower"},"readings":{"ec_high":"higher","runoff_ec_high":"higher","ec_low":"lower"}},"rule_out_first":["cause-overwatering","cause-ammonium-toxicity","cause-heat-stress"],"distinguishing_questions":["q-pot-weight","q-feed-strength","q-ec-input","q-recent-changes"],"tests":["test-runoff-ec","test-lift-pot"],"fix":"Cut feed N by 20-30% (or the whole feed EC by ~0.3-0.5 mS/cm); for a heavy overdose in containers, run a root-zone flush with pH-adjusted, quarter-strength feed to 20-30% runoff. In flower, taper N while keeping P, K, Ca, Mg, S and micros fed.","confirm":"New leaves come in lighter green and flat within 5-7 days; clawed leaves relax partly.","urgency":"low","house_position":false,"article":"kb-nutrients-nitrogen","sources":["Saloner A, Bernstein N. 2021. Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis (Cannabis sativa L.). Industrial Crops and Products 167:113516. https://doi.org/10.1016/j.indcrop.2021.113516","Bevan L, Jones M, Zheng Y. 2021. Optimisation of nitrogen, phosphorus, and potassium for soilless production of Cannabis sativa in the flowering stage using response surface analysis. Frontiers in Plant Science 12:764103. https://doi.org/10.3389/fpls.2021.764103"]},{"id":"cause-ammonium-toxicity","label":"Ammonium toxicity (too much NH4 in the feed)","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-clawing-dark":"typical","sym-scorched-margins-old":"typical","sym-rust-spots-new":"possible","sym-roots-stained-firm":"possible","sym-stubby-root-tips":"possible","sym-ph-falling":"typical"},"contexts":{"recent_changes":{"new_feed":"higher"},"medium":{"water":"higher","coco":"higher","living_soil":"lower"},"readings":{"ph_low":"higher"}},"rule_out_first":["cause-n-toxicity","cause-ph-low-lockout","cause-root-rot-pythium"],"distinguishing_questions":["q-recent-changes","q-ph-runoff","q-root-colour"],"tests":["test-ph-input-runoff","test-root-inspection"],"fix":"Keep ammonium at or below about 10-30% of total N (cannabis trials showed toxicity and lost yield above ~30%); switch to a mostly nitrate feed and correct root-zone pH.","confirm":"pH stops falling and new leaves lose the dark claw within a week.","urgency":"medium","house_position":false,"article":"kb-nutrients-nitrogen","sources":["Saloner A, Bernstein N. 2022. Nitrogen source matters: high NH4/NO3 ratio reduces cannabinoids, terpenoids, and yield in medical cannabis. Frontiers in Plant Science 13:830224. https://doi.org/10.3389/fpls.2022.830224","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-p-excess","label":"Excess phosphorus (bloom boosters) inducing Zn, Fe and Ca shortages","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-interveinal-yellow-new":"typical","sym-yellow-new-margins":"possible","sym-rust-spots-new":"possible","sym-runoff-ec-high":"possible"},"contexts":{"feed_strength":{"heavy":"higher"},"stage":{"early_flower":"higher","late_flower":"higher"},"recent_changes":{"new_feed":"higher","feed_increase":"higher"}},"rule_out_first":["cause-ph-high-lockout","cause-zn-deficiency","cause-fe-deficiency"],"distinguishing_questions":["q-feed-strength","q-recent-changes","q-ph-runoff"],"tests":["test-runoff-ec","test-leaf-tissue"],"fix":"Drop the booster. Keep P at about 30-60 mg/L; four controlled cannabis trials found no yield or cannabinoid gain above roughly 25-60 mg/L, and excess P just leaves in the runoff.","confirm":"New growth greens within 10 days of returning to a balanced feed.","urgency":"low","house_position":true,"article":"kb-nutrients-bloom-boosters","sources":["Westmoreland FM, Bugbee B. 2022. Sustainable cannabis nutrition: elevated root-zone phosphorus significantly increases leachate P and does not improve yield or quality. Frontiers in Plant Science 13:1015652. https://doi.org/10.3389/fpls.2022.1015652","Hershkowitz JA, Westmoreland FM, Bugbee B. 2025. Elevated root-zone P and nutrient concentration do not increase yield or cannabinoids in medical cannabis. Frontiers in Plant Science 16:1433985. https://doi.org/10.3389/fpls.2025.1433985","Shiponi S, Bernstein N. 2021. The highs and lows of P supply in medical cannabis: effects on cannabinoids, the ionome, and morpho-physiology. Frontiers in Plant Science 12:657323. https://doi.org/10.3389/fpls.2021.657323"]},{"id":"cause-k-excess","label":"Excess potassium crowding out magnesium and calcium","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-interveinal-yellow-old":"typical","sym-rust-spots-new":"possible","sym-burnt-tips":"possible"},"contexts":{"feed_strength":{"heavy":"higher"},"stage":{"early_flower":"higher","late_flower":"higher"},"recent_changes":{"new_feed":"higher","feed_increase":"higher"}},"rule_out_first":["cause-mg-deficiency","cause-ph-low-lockout","cause-salt-buildup"],"distinguishing_questions":["q-feed-strength","q-recent-changes","q-ec-runoff"],"tests":["test-runoff-ec","test-leaf-tissue"],"fix":"Stop K boosters and keep K near 175-250 mg/L; cation antagonism (K vs Mg and Ca) is the interaction that reliably matters in practice.","confirm":"Interveinal yellowing stops climbing in 7 days.","urgency":"low","house_position":false,"article":"kb-nutrients-nutrient-antagonism","sources":["Saloner A, Bernstein N. 2022. Effect of potassium (K) supply on cannabinoids, terpenoids and plant function in medical cannabis. Agronomy 12(5):1242. https://doi.org/10.3390/agronomy12051242","Rietra RPJJ, Heinen M, Dimkpa CO, Bindraban PS. 2017. Effects of nutrient antagonism and synergism on yield and fertilizer use efficiency. Communications in Soil Science and Plant Analysis 48(16):1895-1920. https://doi.org/10.1080/00103624.2017.1407429"]},{"id":"cause-calcium-excess","label":"Cal-Mag overuse (excess calcium and nitrogen)","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-interveinal-yellow-old":"typical","sym-yellow-margins-old":"possible","sym-dark-green-leaves":"possible","sym-white-scale-equipment":"rare","sym-runoff-ec-high":"possible"},"contexts":{"calmag":{"yes":"higher","no":"lower"},"water_source":{"well":"higher","tap_chlorine":"higher","tap_chloramine":"higher","ro":"lower"}},"rule_out_first":["cause-k-deficiency","cause-mg-deficiency","cause-salt-buildup"],"distinguishing_questions":["q-calmag","q-water-source","q-ec-runoff"],"tests":["test-water-report","test-runoff-ec"],"fix":"On hard tap water with a complete base feed, stop the Cal-Mag supplement; it adds N and pushes K and Mg out of balance. Use it only for RO or soft water and unbuffered coco. LEDs do not create a Cal-Mag need.","confirm":"K and Mg symptoms stop spreading within 7-10 days.","urgency":"low","house_position":true,"article":"kb-nutrients-cal-mag","sources":["Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6","Rietra RPJJ, Heinen M, Dimkpa CO, Bindraban PS. 2017. Effects of nutrient antagonism and synergism on yield and fertilizer use efficiency. Communications in Soil Science and Plant Analysis 48(16):1895-1920. https://doi.org/10.1080/00103624.2017.1407429"]},{"id":"cause-fe-toxicity","label":"Iron and manganese excess at very low pH","kind":"toxicity","base_rate":"rare","symptoms":{"sym-brown-speckles-old":"typical","sym-bronze-leaves":"possible"},"contexts":{"readings":{"ph_low":"higher","ph_high":"lower"}},"rule_out_first":["cause-ph-low-lockout","cause-mn-toxicity","cause-russet-mites"],"distinguishing_questions":["q-ph-runoff","q-magnifier-underside"],"tests":["test-ph-input-runoff","test-magnifier"],"fix":"Raise root-zone pH above ~5.5 (soilless) or 6.0 (soil); below about 5.3, Fe and Mn become very soluble. Cannabis Fe toxicity itself is not characterised.","confirm":"No new speckling on leaves that develop after pH correction.","urgency":"low","house_position":false,"article":"kb-nutrients-iron","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-mn-toxicity","label":"Manganese toxicity (usually low pH)","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-yellow-margins-old":"typical","sym-scorched-margins-old":"typical","sym-brown-speckles-old":"hallmark","sym-lower-leaves-dying-fast":"possible"},"contexts":{"readings":{"ph_low":"higher","ph_high":"lower"},"medium":{"soil":"higher"}},"rule_out_first":["cause-ph-low-lockout","cause-k-deficiency","cause-b-toxicity"],"distinguishing_questions":["q-ph-runoff","q-where-first"],"tests":["test-ph-input-runoff","test-leaf-tissue"],"fix":"Raise root-zone pH into range (soilless 5.8-6.2, soil 6.2-6.8); check that the micro mix is not over-dosed. Tissue tests may not flag it: in one trial, symptomatic plants had normal leaf Mn.","confirm":"Margin yellowing stops climbing within 7 days.","urgency":"low","house_position":false,"article":"kb-nutrients-manganese","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-zn-toxicity","label":"Zinc toxicity (galvanised fittings, over-dosed micros)","kind":"toxicity","base_rate":"rare","symptoms":{"sym-interveinal-yellow-new":"typical","sym-stunted":"possible"},"contexts":{"system":{"recirc":"higher","dwc":"higher","nft":"higher"}},"rule_out_first":["cause-fe-deficiency","cause-ph-high-lockout"],"distinguishing_questions":["q-system","q-ph-runoff"],"tests":["test-leaf-tissue","test-water-report"],"fix":"Remove galvanised fittings from recirculating water; cap Zn near 0.1-0.5 mg/L. Excess Zn induces iron deficiency.","confirm":"New leaves green within 10-14 days.","urgency":"low","house_position":false,"article":"kb-nutrients-zinc","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-b-toxicity","label":"Boron toxicity","kind":"toxicity","base_rate":"rare","symptoms":{"sym-yellow-margins-old":"hallmark","sym-scorched-margins-old":"typical"},"contexts":{"water_source":{"well":"higher"}},"rule_out_first":["cause-k-deficiency","cause-salt-buildup","cause-mn-toxicity"],"distinguishing_questions":["q-water-source","q-ec-runoff"],"tests":["test-water-report","test-leaf-tissue"],"fix":"Test the water (some wells carry B) and stop extra boron products; supply only 0.2-0.5 mg/L B in total. Cannabis tolerated about 10x for weeks, but symptoms appeared after 7 weeks at ~4.9 mg/L.","confirm":"No new margin scorch on leaves that mature after the change.","urgency":"low","house_position":false,"article":"kb-nutrients-boron","sources":["Cockson P, et al. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432"]},{"id":"cause-cu-toxicity","label":"Copper toxicity (copper sprays, ionisers, pipework)","kind":"toxicity","base_rate":"rare","symptoms":{"sym-stubby-root-tips":"hallmark","sym-interveinal-yellow-new":"typical","sym-stunted":"typical"},"contexts":{"system":{"recirc":"higher","dwc":"higher"}},"rule_out_first":["cause-root-rot-pythium","cause-salt-buildup"],"distinguishing_questions":["q-root-colour","q-system","q-recent-changes"],"tests":["test-root-inspection","test-water-report"],"fix":"Stop copper fungicides and ionisers, replace copper pipework contact; change the reservoir. Keep Cu at about 0.03-0.1 mg/L.","confirm":"New white root tips within a week.","urgency":"medium","house_position":false,"article":"kb-nutrients-copper","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-sodium-toxicity","label":"Sodium build-up (softened water, coco, recirculation)","kind":"toxicity","base_rate":"uncommon","symptoms":{"sym-burnt-tips":"typical","sym-scorched-margins-old":"typical","sym-dull-grey-leaves":"typical","sym-stunted":"possible","sym-runoff-ec-high":"typical"},"contexts":{"water_source":{"softened":"higher","well":"higher","ro":"lower"},"medium":{"coco":"higher"},"system":{"recirc":"higher","dwc":"higher"},"readings":{"sodium_high":"higher","runoff_ec_high":"higher"}},"rule_out_first":["cause-salt-buildup","cause-k-deficiency","cause-overfeeding"],"distinguishing_questions":["q-water-source","q-ec-runoff","q-system"],"tests":["test-water-report","test-runoff-ec","test-leaf-tissue"],"fix":"Never use ion-exchange softened water. Keep feed sodium below about 50 mg/L (more than ~5 mM NaCl, 115 mg/L Na, may cut hydro yield and cannabinoids fall as NaCl rises). Dump and refill recirculating reservoirs more often; rinse coco before planting.","confirm":"Tip burn stops advancing on new leaves within a week.","urgency":"medium","house_position":false,"article":"kb-nutrients-sodium","sources":["Yep B, Gale NV, Zheng Y. 2020. Aquaponic and hydroponic solutions modulate NaCl-induced stress in drug-type Cannabis sativa L. Frontiers in Plant Science 11:1169. https://doi.org/10.3389/fpls.2020.01169","Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6"]},{"id":"cause-chloride-toxicity","label":"Chloride excess (salinity)","kind":"toxicity","base_rate":"rare","symptoms":{"sym-burnt-tips":"typical","sym-scorched-margins-old":"possible","sym-dull-grey-leaves":"possible"},"contexts":{"water_source":{"well":"higher","softened":"higher"},"medium":{"coco":"higher"}},"rule_out_first":["cause-sodium-toxicity","cause-salt-buildup"],"distinguishing_questions":["q-water-source","q-ec-runoff"],"tests":["test-water-report","test-runoff-ec"],"fix":"Keep chloride below about 50-70 mg/L in the feed; switch potassium chloride for potassium sulfate; blend high-chloride water with RO.","confirm":"No new tip burn after the change.","urgency":"low","house_position":false,"article":"kb-nutrients-chlorine","sources":["Yep B, Gale NV, Zheng Y. 2020. Aquaponic and hydroponic solutions modulate NaCl-induced stress in drug-type Cannabis sativa L. Frontiers in Plant Science 11:1169. https://doi.org/10.3389/fpls.2020.01169","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-overfeeding","label":"Nutrient burn (feed too strong)","kind":"toxicity","base_rate":"very_common","symptoms":{"sym-burnt-tips":"hallmark","sym-clawing-dark":"typical","sym-dark-green-leaves":"typical","sym-scorched-margins-old":"possible","sym-runoff-ec-high":"typical","sym-ec-rising":"typical","sym-stubby-root-tips":"possible"},"contexts":{"feed_strength":{"heavy":"higher","full":"higher","none":"lower","light":"lower"},"stage":{"seedling":"higher","clone":"higher"},"recent_changes":{"feed_increase":"higher","new_feed":"higher"},"medium":{"soil":"higher"},"readings":{"ec_high":"higher","runoff_ec_high":"higher","ec_low":"lower"}},"rule_out_first":["cause-salt-buildup","cause-heat-stress","cause-sodium-toxicity"],"distinguishing_questions":["q-feed-strength","q-ec-input","q-ec-runoff","q-stage","q-recent-changes"],"tests":["test-runoff-ec","test-pour-through"],"fix":"Drop input EC by 0.3-0.5 mS/cm (or to about two-thirds strength); seedlings and clones need 0.4-1.0 mS/cm. Soil with pre-loaded nutrients usually needs plain pH-adjusted water for the first 2-4 weeks. If runoff is far above input, do a root-zone flush (see salt build-up).","confirm":"No new tip burn on leaves that open after the change, within 5-7 days; burnt tips stay.","urgency":"low","house_position":false,"article":"kb-diagnosis-brown-burnt-tips","sources":["Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6","NC State University / NC Department of Agriculture and Consumer Services. The pour-through extraction procedure: a nutrient management tool for nursery crops. https://ncagr.gov/ncsu-pour-through-extraction"]},{"id":"cause-salt-buildup","label":"Salt build-up in the root zone","kind":"root_zone","base_rate":"common","symptoms":{"sym-runoff-ec-high":"hallmark","sym-burnt-tips":"typical","sym-salt-crust-medium":"typical","sym-dull-grey-leaves":"possible","sym-yellow-margins-old":"possible","sym-stunted":"possible","sym-midday-wilt":"possible","sym-stubby-root-tips":"possible"},"contexts":{"medium":{"coco":"higher","soil":"higher","water":"lower","living_soil":"lower"},"system":{"hand_water":"higher","wick":"higher","drip_dtw":"lower"},"watering_frequency":{"before_dry":"lower"},"readings":{"runoff_ec_high":"higher","runoff_ec_low":"lower"}},"rule_out_first":["cause-overfeeding","cause-meter-error"],"distinguishing_questions":["q-ec-runoff","q-ec-input","q-watering-frequency","q-medium"],"tests":["test-runoff-ec","test-pour-through","test-slurry"],"fix":"Root-zone flush: water slowly with pH-adjusted, quarter- to half-strength feed (not plain water in coco) to 20-30% runoff, about 2-3x the pot volume, until runoff EC is within ~0.3-0.5 mS/cm of input. Then water to 10-20% runoff each time. This treats the medium, not the plant; it is not a pre-harvest flush, which is a myth.","confirm":"Runoff EC tracks input at the next 2-3 waterings; new leaves stop burning.","urgency":"medium","house_position":true,"article":"kb-ph-ec-runoff-testing","sources":["NC State University / NC Department of Agriculture and Consumer Services. The pour-through extraction procedure: a nutrient management tool for nursery crops. https://ncagr.gov/ncsu-pour-through-extraction","Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6","GenetixBay house position: pre-harvest flushing is a myth (see kb-harvest-cure-flush-debate for the controlled studies)."]},{"id":"cause-ph-high-lockout","label":"High root-zone pH locking out iron, manganese, zinc, boron and copper","kind":"ph_lockout","base_rate":"very_common","symptoms":{"sym-interveinal-yellow-new":"hallmark","sym-netted-yellow-upper-spots":"typical","sym-yellow-new-growth":"typical","sym-white-new-growth":"possible","sym-yellow-new-margins":"possible","sym-small-narrow-new-leaves":"possible","sym-ph-rising":"typical","sym-stunted":"possible"},"contexts":{"readings":{"ph_high":"higher","alkalinity_high":"higher","ph_low":"lower"},"water_source":{"well":"higher","tap_chlorine":"higher","tap_chloramine":"higher","ro":"lower"},"medium":{"soil":"higher","coco":"higher","rockwool":"higher"},"spread":{"all_plants":"higher","one_plant":"lower"}},"rule_out_first":["cause-meter-error","cause-high-alkalinity-water","cause-overwatering"],"distinguishing_questions":["q-ph-runoff","q-ph-input","q-alkalinity","q-water-source","q-spread"],"tests":["test-ph-input-runoff","test-meter-calibration","test-water-report","test-pour-through"],"fix":"Bring root-zone pH into range: soil 6.2-6.8, coco and rockwool 5.8-6.2, hydro 5.5-6.2. Lower input pH by 0.2-0.3 units at a time rather than crashing it; neutralise alkaline water with a mineral acid (phosphoric, nitric or sulfuric; wear gloves and eye protection, add acid to water). Use an iron chelate stable at your pH (DTPA or EDDHA above 6.5).","confirm":"Runoff or reservoir pH back in range at two consecutive checks; new leaves open green within 5-10 days.","urgency":"medium","house_position":false,"article":"kb-ph-ec-ph-nutrient-availability","sources":["Lopez RG, Mickelbart MV, Pasian C. Alkalinity management in soilless substrates. Purdue Extension HO-242-W. https://www.extension.purdue.edu/extmedia/HO/HO-242-W.pdf","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9","Velechovsky J, Malik M, Senkyrik JB, Tlustos P. 2024. Frontiers in Plant Science 15:1322824. https://doi.org/10.3389/fpls.2024.1322824"]},{"id":"cause-ph-high-p-lockout","label":"High pH reducing phosphorus availability","kind":"ph_lockout","base_rate":"uncommon","symptoms":{"sym-olive-spots-old":"typical","sym-dark-dull-purple-blotch":"typical","sym-stunted":"possible"},"contexts":{"readings":{"ph_high":"higher","alkalinity_high":"higher","ph_low":"lower"},"medium":{"soil":"higher","living_soil":"higher"}},"rule_out_first":["cause-cold-stress","cause-meter-error","cause-genetic-anthocyanin"],"distinguishing_questions":["q-ph-runoff","q-night-temp","q-cultivar-purple"],"tests":["test-ph-input-runoff","test-slurry","test-water-report"],"fix":"Bring soil pH to 6.2-6.8 (soilless 5.8-6.2) and neutralise alkaline water; above about pH 7, phosphate precipitates with calcium. Do not add more P to compensate.","confirm":"No new olive spots on leaves that open after pH correction.","urgency":"medium","house_position":false,"article":"kb-ph-ec-ph-nutrient-availability","sources":["Lopez RG, Mickelbart MV, Pasian C. Alkalinity management in soilless substrates. Purdue Extension HO-242-W. https://www.extension.purdue.edu/extmedia/HO/HO-242-W.pdf","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-ph-low-lockout","label":"Low root-zone pH starving calcium and magnesium","kind":"ph_lockout","base_rate":"common","symptoms":{"sym-rust-spots-new":"hallmark","sym-interveinal-yellow-old":"typical","sym-twisted-new-growth":"possible","sym-brown-speckles-old":"possible","sym-yellow-lower-leaves":"possible","sym-ph-falling":"typical"},"contexts":{"readings":{"ph_low":"higher","ph_high":"lower"},"medium":{"coco":"higher","water":"higher","rockwool":"higher"},"water_source":{"ro":"higher","rain":"higher"},"recent_changes":{"ph_change":"higher","new_feed":"higher"}},"rule_out_first":["cause-meter-error","cause-ammonium-toxicity","cause-root-rot-pythium"],"distinguishing_questions":["q-ph-runoff","q-ph-input","q-water-source","q-recent-changes"],"tests":["test-ph-input-runoff","test-meter-calibration","test-pour-through"],"fix":"Raise root-zone pH to range: coco 5.8-6.2, hydro 5.6-6.0, soil 6.2-6.8. Use pH up (potassium hydroxide or carbonate) in small steps; in coco, feed at 6.0-6.2 for a few waterings with Ca and Mg on board. A fast fall in hydro points to dying roots or microbes; check them.","confirm":"pH holds in range for a week; new leaves spot-free within 7-10 days.","urgency":"medium","house_position":false,"article":"kb-ph-ec-ph-nutrient-availability","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9","Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6","Velechovsky J, Malik M, Senkyrik JB, Tlustos P. 2024. Frontiers in Plant Science 15:1322824. https://doi.org/10.3389/fpls.2024.1322824"]},{"id":"cause-ph-low-mo-lockout","label":"Very low pH limiting molybdenum","kind":"ph_lockout","base_rate":"rare","symptoms":{"sym-yellow-middle-leaves":"typical","sym-whole-plant-pale":"possible"},"contexts":{"readings":{"ph_low":"higher","ph_high":"lower"}},"rule_out_first":["cause-ph-low-lockout","cause-n-deficiency"],"distinguishing_questions":["q-ph-runoff"],"tests":["test-ph-input-runoff","test-leaf-tissue"],"fix":"Raise pH into range; Mo becomes more available as pH rises, unlike the other micros. Cannabis showed no visible Mo symptoms in a 9-week trial, so look harder for other causes.","confirm":"Pale middle leaves stop spreading.","urgency":"low","house_position":false,"article":"kb-nutrients-molybdenum","sources":["Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-meter-error","label":"Uncalibrated or failing pH or EC meter","kind":"physical","base_rate":"common","symptoms":{"sym-interveinal-yellow-new":"typical","sym-rust-spots-new":"typical","sym-ph-rising":"possible","sym-ph-falling":"possible","sym-runoff-ec-high":"possible"},"contexts":{"recent_changes":{"ph_change":"higher"}},"rule_out_first":[],"distinguishing_questions":["q-recent-changes","q-ph-runoff"],"tests":["test-meter-calibration"],"fix":"Calibrate the pH meter with fresh pH 7 then pH 4 buffer before decisions and at least weekly; store the probe wet in storage solution, never in RO water. Check EC against 1.413 mS/cm. Replace probes that won't calibrate (typical life 1-2 years). Drops and strips are too coarse to diagnose with.","confirm":"Readings match the buffers within 0.1 pH; the 'problem' pH disappears or is confirmed.","urgency":"medium","house_position":false,"article":"kb-ph-ec-meter-calibration","sources":["Prasad L, Meehan M. Using electrical conductivity and total dissolved solids meters to field test water quality. NDSU Extension WQ1923 (rev. 2025). https://www.ndsu.edu/agriculture/extension/publications/using-electrical-conductivity-and-total-dissolved-solids-meters-field-test-water-quality"]},{"id":"cause-high-alkalinity-water","label":"Hard, alkaline water pushing pH up over weeks","kind":"root_zone","base_rate":"common","symptoms":{"sym-ph-rising":"hallmark","sym-interveinal-yellow-new":"typical","sym-white-scale-equipment":"typical","sym-white-residue":"possible","sym-salt-crust-medium":"possible"},"contexts":{"water_source":{"well":"higher","tap_chlorine":"higher","tap_chloramine":"higher","ro":"lower","rain":"lower"},"readings":{"alkalinity_high":"higher","ph_high":"higher"},"medium":{"soil":"higher","coco":"higher"}},"rule_out_first":["cause-meter-error"],"distinguishing_questions":["q-water-source","q-alkalinity","q-ph-runoff"],"tests":["test-water-report","test-ph-input-runoff","test-pour-through"],"fix":"Alkalinity, not water pH, drives the climb. Above about 100-150 mg/L as CaCO3 (2-3 meq/L), neutralise most of it with acid to an input pH of 5.8-6.2, or blend with RO water. Track runoff pH weekly.","confirm":"Runoff pH stops climbing over 2-3 weeks.","urgency":"low","house_position":false,"article":"kb-ph-ec-water-quality","sources":["Lopez RG, Mickelbart MV, Pasian C. Alkalinity management in soilless substrates. Purdue Extension HO-242-W. https://www.extension.purdue.edu/extmedia/HO/HO-242-W.pdf","NC State Extension. Producing conventional tobacco transplants in greenhouses: water quality. https://content.ces.ncsu.edu/producing-conventional-tobacco-transplants-in-greenhouses-water-quality"]},{"id":"cause-chloramine","label":"Chlorine or chloramine in tap water harming roots and soil life","kind":"root_zone","base_rate":"uncommon","symptoms":{"sym-seedling-stalled":"typical","sym-stunted":"possible","sym-no-new-root-tips":"possible","sym-clone-wilting":"rare"},"contexts":{"water_source":{"tap_chloramine":"higher","tap_chlorine":"higher","ro":"lower","well":"lower","rain":"lower"},"medium":{"living_soil":"higher","water":"lower"},"stage":{"seedling":"higher","clone":"higher"}},"rule_out_first":["cause-overwatering","cause-low-light","cause-damping-off"],"distinguishing_questions":["q-water-source","q-medium","q-stage"],"tests":["test-water-report"],"fix":"Usual tap levels rarely hurt the plant directly; the concern is living soil, beneficial microbes and young roots. Chlorine gasses off in 24 h of aeration; chloramine does not. Remove chloramine with long-contact or catalytic carbon, or about 1 g of ascorbic acid per 100-400 L, or use RO.","confirm":"Biology recovers over weeks; seedlings resume growth within a week.","urgency":"low","house_position":false,"article":"kb-ph-ec-water-quality","sources":["Water Quality Association. 2014. Chloramine fact sheet. https://wqa.org/wp-content/uploads/2022/09/2014_Chloramine.pdf","USDA Forest Service. Vitamin C dechlorination. https://www.fs.usda.gov/t-d/pubs/html/05231301/05231301.html"]},{"id":"cause-overwatering","label":"Overwatering (roots short of air)","kind":"root_zone","base_rate":"very_common","symptoms":{"sym-plant-not-drinking":"typical","sym-water-pools-slow-drain":"typical","sym-droop-wet-pot":"hallmark","sym-curl-down-wet":"hallmark","sym-medium-stays-wet":"hallmark","sym-yellow-lower-leaves":"typical","sym-whole-plant-pale":"typical","sym-clawing-dark":"possible","sym-stunted":"typical","sym-gnats-flying":"typical","sym-larvae-in-medium":"possible","sym-oedema-bumps":"possible","sym-yellow-cotyledons":"typical","sym-seedling-stalled":"typical","sym-root-zone-smell":"possible","sym-auto-small":"possible"},"contexts":{"watering_frequency":{"before_dry":"higher","bone_dry":"lower","high_freq":"lower"},"pot_weight":{"heavy":"higher","light":"lower"},"pot_size":{"too_big":"higher"},"stage":{"seedling":"higher","clone":"higher"},"medium":{"soil":"higher","living_soil":"higher","water":"lower","coco":"lower"},"readings":{"temp_low":"higher","vpd_low":"higher"}},"rule_out_first":["cause-root-rot-pythium"],"distinguishing_questions":["q-pot-weight","q-watering-frequency","q-pot-size","q-stage","q-medium"],"tests":["test-lift-pot","test-root-inspection","test-root-smell"],"fix":"Water only when the pot is clearly lighter (about half the water used), then water to 10-20% runoff. Seedlings in big pots: water a small ring near the stem only. Add air: fabric pots, 25-40% perlite, no saucer standing water. Let a soaked pot dry back before the next watering.","confirm":"Leaves lift within a day of drying back; colour and growth recover within 5-7 days.","urgency":"medium","house_position":false,"article":"kb-diagnosis-drooping-overwatering-vs-underwatering","sources":["Poorter H, Buhler J, van Dusschoten D, Climent J, Postma JA. 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth. Functional Plant Biology 39(11):839-850. https://doi.org/10.1071/FP12049","Raviv M, Lieth JH, Bar-Tal A (eds). 2019. Soilless Culture: Theory and Practice, 2nd ed. Elsevier. https://doi.org/10.1016/C2015-0-01807-5","UC IPM. Pest Notes: Fungus Gnats (Publication 7448). https://ipm.ucanr.edu/legacy_assets/pdf/pestnotes/pnfungusgnats.pdf"]},{"id":"cause-underwatering","label":"Underwatering","kind":"root_zone","base_rate":"common","symptoms":{"sym-wilt-dry-pot":"hallmark","sym-medium-dries-fast":"typical","sym-crispy-top-leaves":"possible","sym-lower-leaves-dying-fast":"possible","sym-midday-wilt":"typical","sym-stunted":"possible"},"contexts":{"pot_weight":{"light":"higher","heavy":"lower"},"watering_frequency":{"bone_dry":"higher","before_dry":"lower"},"pot_size":{"too_small":"higher"},"readings":{"vpd_high":"higher","temp_high":"higher","rh_low":"higher"}},"rule_out_first":["cause-root-bound","cause-hydrophobic-medium","cause-root-rot-pythium"],"distinguishing_questions":["q-pot-weight","q-watering-frequency","q-pot-size"],"tests":["test-lift-pot"],"fix":"Water slowly in 2-3 passes until 10-20% runoff, so the whole root ball wets. Water when the pot is clearly lighter, before the plant droops. Mild late-flower dry-back is a house-endorsed practice for some cultivars (Caplan 2019), but wilting is not.","confirm":"Turgor returns within 1-6 hours of watering.","urgency":"high","house_position":false,"article":"kb-diagnosis-drooping-overwatering-vs-underwatering","sources":["Caplan D, Dixon M, Zheng Y. 2019. Increasing inflorescence dry weight and cannabinoid content in medical cannabis using controlled drought stress. HortScience 54(5):964-969. https://doi.org/10.21273/HORTSCI13510-18","Raviv M, Lieth JH, Bar-Tal A (eds). 2019. Soilless Culture: Theory and Practice, 2nd ed. Elsevier. https://doi.org/10.1016/C2015-0-01807-5"]},{"id":"cause-hydrophobic-medium","label":"Dry, water-repellent medium (water runs straight through)","kind":"root_zone","base_rate":"uncommon","symptoms":{"sym-medium-dries-fast":"hallmark","sym-wilt-dry-pot":"typical","sym-midday-wilt":"possible"},"contexts":{"medium":{"soil":"higher","coco":"lower","water":"lower"},"watering_frequency":{"bone_dry":"higher"}},"rule_out_first":["cause-root-bound"],"distinguishing_questions":["q-medium","q-watering-frequency","q-pot-size"],"tests":["test-lift-pot"],"fix":"Rewet slowly: small amounts every 10-15 minutes, or bottom-soak the pot for 20-30 minutes; a drop of plant-safe wetting agent helps peat. Don't let peat mixes go bone dry again.","confirm":"Pot gains its normal wet weight and holds it for a day or more.","urgency":"medium","house_position":false,"article":"kb-answers-water-runs-through-or-pools","sources":["Raviv M, Lieth JH, Bar-Tal A (eds). 2019. Soilless Culture: Theory and Practice, 2nd ed. Elsevier. https://doi.org/10.1016/C2015-0-01807-5"]},{"id":"cause-root-bound","label":"Root-bound in a pot too small","kind":"root_zone","base_rate":"common","symptoms":{"sym-water-pools-slow-drain":"possible","sym-roots-circling":"hallmark","sym-medium-dries-fast":"typical","sym-midday-wilt":"typical","sym-stunted":"typical","sym-whole-plant-pale":"possible","sym-lower-leaves-dying-fast":"possible"},"contexts":{"pot_size":{"too_small":"higher","too_big":"lower"},"stage":{"veg":"higher","clone":"lower"},"root_colour":{"circling":"higher"}},"rule_out_first":["cause-underwatering","cause-underfeeding"],"distinguishing_questions":["q-pot-size","q-root-colour","q-watering-frequency"],"tests":["test-root-inspection","test-lift-pot"],"fix":"Up-pot photoperiods into a container about 2-3x larger, loosening circling roots gently. Autoflowers: don't transplant; increase watering and feeding frequency instead. Small pots can still grow big plants with high-frequency fertigation (several feeds a day).","confirm":"New white roots in the fresh medium within 5-7 days; daily wilting stops.","urgency":"medium","house_position":true,"article":"kb-diagnosis-root-problems-decision-tree","sources":["Poorter H, Buhler J, van Dusschoten D, Climent J, Postma JA. 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth. Functional Plant Biology 39(11):839-850. https://doi.org/10.1071/FP12049"]},{"id":"cause-low-dissolved-oxygen","label":"Low dissolved oxygen in the root zone","kind":"root_zone","base_rate":"common","symptoms":{"sym-plant-not-drinking":"possible","sym-no-new-root-tips":"typical","sym-roots-brown-slimy":"possible","sym-root-zone-smell":"typical","sym-wilt-moist-not-recovering":"typical","sym-midday-wilt":"typical","sym-sudden-yellowing":"possible","sym-stunted":"typical"},"contexts":{"system":{"dwc":"higher","kratky":"higher","nft":"higher","recirc":"higher","hand_water":"lower"},"medium":{"water":"higher","soil":"lower"},"readings":{"do_low":"higher","res_temp_high":"higher"},"root_smell":{"yes":"higher"}},"rule_out_first":["cause-pump-failure","cause-hot-reservoir"],"distinguishing_questions":["q-do","q-res-temp","q-system","q-root-colour","q-root-smell"],"tests":["test-dissolved-oxygen","test-reservoir-temp","test-root-inspection","test-pump-check"],"fix":"Restore oxygen: clean or replace air stones, size the air pump for at least ~1 L/min per 4 L, keep a 2-5 cm air gap under net pots once roots reach the water, cool the solution to 18-22 °C (64-72 °F). Aim for 6-8+ mg/L DO.","confirm":"Fresh white root tips within 3-5 days; wilting stops.","urgency":"high","house_position":false,"article":"kb-systems-dwc","sources":["University of Kentucky Cooperative Extension. Pythium root rot in hydroponic production (E-706). https://greenhousehort.ca.uky.edu/sites/greenhousehort.ca.uky.edu/files/E706.pdf","Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/"]},{"id":"cause-hot-reservoir","label":"Reservoir or root zone too warm","kind":"root_zone","base_rate":"common","symptoms":{"sym-reservoir-warm":"hallmark","sym-roots-brown-slimy":"typical","sym-root-zone-smell":"typical","sym-wilt-moist-not-recovering":"typical","sym-midday-wilt":"typical","sym-reservoir-cloudy":"possible"},"contexts":{"system":{"dwc":"higher","recirc":"higher","nft":"higher","kratky":"higher","aero_lpa":"higher","hand_water":"lower"},"readings":{"res_temp_high":"higher","temp_high":"higher"}},"rule_out_first":["cause-pump-failure"],"distinguishing_questions":["q-res-temp","q-system","q-air-temp"],"tests":["test-reservoir-temp","test-dissolved-oxygen"],"fix":"Keep solution at 18-22 °C (64-72 °F): insulate and shade the reservoir, move it off the warm floor or away from the light, use a chiller or frozen water bottles in an emergency, avoid submersible pumps that add heat, cool the room.","confirm":"Solution holds below 22 °C through the light period; new white roots in 3-5 days.","urgency":"high","house_position":false,"article":"kb-diagnosis-root-browning-hydro","sources":["University of Kentucky Cooperative Extension. Pythium root rot in hydroponic production (E-706). https://greenhousehort.ca.uky.edu/sites/greenhousehort.ca.uky.edu/files/E706.pdf","Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/"]},{"id":"cause-cold-root-zone","label":"Cold root zone (below about 16 °C / 61 °F)","kind":"root_zone","base_rate":"uncommon","symptoms":{"sym-plant-not-drinking":"typical","sym-reservoir-cold":"hallmark","sym-stunted":"typical","sym-whole-plant-pale":"typical","sym-dark-dull-purple-blotch":"possible","sym-purple-stems":"possible","sym-medium-stays-wet":"typical","sym-yellow-lower-leaves":"possible"},"contexts":{"readings":{"res_temp_low":"higher","temp_low":"higher","night_cold":"higher"},"recent_changes":{"cold_event":"higher"}},"rule_out_first":["cause-overwatering","cause-genetic-anthocyanin"],"distinguishing_questions":["q-res-temp","q-night-temp","q-medium"],"tests":["test-reservoir-temp","test-lift-pot"],"fix":"Raise root-zone temperature to 18-22 °C (64-72 °F): lift pots off cold floors onto insulation, warm the room at night, use an aquarium heater in reservoirs (with a thermostat), water with room-temperature solution.","confirm":"Growth resumes and new leaves green within a week.","urgency":"medium","house_position":false,"article":"kb-environment-temperature-by-stage","sources":["Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/","Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x"]},{"id":"cause-pump-failure","label":"Pump, timer, air or emitter failure in a hydro, aero or drip system","kind":"root_zone","base_rate":"uncommon","symptoms":{"sym-uneven-drip-wetting":"hallmark","sym-sudden-collapse-hydro":"hallmark","sym-wilt-moist-not-recovering":"typical","sym-no-new-root-tips":"possible","sym-reservoir-warm":"possible"},"contexts":{"system":{"aero_hpa":"higher","nft":"higher","aero_lpa":"higher","dwc":"higher","recirc":"higher","drip_dtw":"higher","hand_water":"lower","kratky":"lower","wick":"lower"},"speed":{"hours":"higher","weeks":"lower"},"spread":{"all_plants":"higher","one_plant":"lower"}},"rule_out_first":[],"distinguishing_questions":["q-system","q-speed","q-spread"],"tests":["test-pump-check"],"fix":"Restore flow or air immediately: check power, timer, float switches, filters and nozzles. Mist exposed roots by hand or lower plants into solution while you fix it. In HPA and NFT, fit an alarm and a backup pump; roots die fast when misting or flow stops.","confirm":"Plants regain turgor within hours if roots were not dead; brown, collapsed roots mean rot risk next.","urgency":"critical","house_position":false,"article":"kb-systems-hpa-aeroponics","sources":["Lakhiar IA, Gao J, Syed TN, Chandio FA, Buttar NA. 2018. Modern plant cultivation technologies in agriculture under controlled environment: a review on aeroponics. Journal of Plant Interactions 13(1):338-352. https://doi.org/10.1080/17429145.2018.1472308","GenetixBay Jardin engineering notes, 2026 (system profiles and failure margins)."]},{"id":"cause-root-staining","label":"Harmless root staining (nutrients, tannins, additives)","kind":"root_zone","base_rate":"common","symptoms":{"sym-roots-stained-firm":"hallmark"},"contexts":{"medium":{"water":"higher"},"root_smell":{"no":"higher","yes":"lower"},"root_colour":{"tan_firm":"higher","brown_slimy":"lower"}},"rule_out_first":["cause-root-rot-pythium"],"distinguishing_questions":["q-root-colour","q-root-smell"],"tests":["test-root-inspection","test-root-smell"],"fix":"Nothing to fix if roots are firm, odourless and still growing white tips. Organic additives, humic products and some nutrient colours stain roots tan.","confirm":"New tips keep appearing white; plant grows normally.","urgency":"low","house_position":false,"article":"kb-diagnosis-root-browning-hydro","sources":["University of Kentucky Cooperative Extension. Pythium root rot in hydroponic production (E-706). https://greenhousehort.ca.uky.edu/sites/greenhousehort.ca.uky.edu/files/E706.pdf"]},{"id":"cause-algae","label":"Algae from light reaching wet surfaces or the reservoir","kind":"root_zone","base_rate":"common","symptoms":{"sym-green-slime":"hallmark","sym-reservoir-cloudy":"possible","sym-ph-rising":"possible","sym-gnats-flying":"possible"},"contexts":{"system":{"dwc":"higher","recirc":"higher","nft":"higher","kratky":"higher","drip_dtw":"higher"},"medium":{"rockwool":"higher","water":"higher"}},"rule_out_first":[],"distinguishing_questions":["q-system","q-medium"],"tests":["test-root-inspection"],"fix":"Block all light from reservoirs, tubing and the medium surface (opaque lids, covers on rockwool). Clean surfaces between runs. Algae competes for oxygen and feeds gnats and shore flies.","confirm":"No new green growth within 1-2 weeks of light-proofing.","urgency":"low","house_position":false,"article":"kb-answers-algae-in-reservoir","sources":["Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/"]},{"id":"cause-saprophytic-fungi","label":"Harmless white fungus (mycelium) on organic medium","kind":"root_zone","base_rate":"common","symptoms":{"sym-white-fuzz-medium":"hallmark"},"contexts":{"medium":{"living_soil":"higher","soil":"higher","water":"lower"},"watering_frequency":{"before_dry":"higher"}},"rule_out_first":["cause-damping-off"],"distinguishing_questions":["q-medium","q-watering-frequency"],"tests":["test-lift-pot"],"fix":"Usually beneficial or harmless decomposers on mulch and organic matter. Let the surface dry more between waterings and improve airflow; scrape it off if it bothers you.","confirm":"Plant stays healthy; fuzz recedes as the surface dries.","urgency":"low","house_position":false,"article":"kb-answers-white-fuzz-on-soil","sources":["University of Minnesota Extension. How to prevent seedling damping off. https://extension.umn.edu/solve-problem/how-prevent-seedling-damping"]},{"id":"cause-light-bleaching","label":"Light bleaching at the canopy top","kind":"light","base_rate":"common","symptoms":{"sym-bud-tips-burnt":"typical","sym-bleached-top-leaves":"hallmark","sym-white-new-growth":"typical","sym-taco-leaves":"typical","sym-foxtails":"possible","sym-pistils-brown-early":"possible"},"contexts":{"top_only":{"yes":"higher","no":"lower"},"where_first":{"top_near_light":"higher","old_growth":"lower"},"recent_changes":{"light_change":"higher"},"light_type":{"led":"higher","fluorescent":"lower"},"stage":{"early_flower":"higher","late_flower":"higher"},"readings":{"ppfd_high":"higher","ppfd_low":"lower"}},"rule_out_first":["cause-heat-stress"],"distinguishing_questions":["q-top-only","q-ppfd","q-recent-changes","q-where-first"],"tests":["test-ppfd-meter","test-leaf-temperature"],"fix":"Raise or dim the light by 10-20% so top-canopy PPFD sits around 800-1,100 µmol/m²/s at ambient CO2 (up to ~1,500 with CO2 and good climate). Keep the canopy even so one cola doesn't sit in a hotspot. Bleached tissue won't re-green.","confirm":"No new bleaching within 3-5 days; new bracts and leaves at the top stay green.","urgency":"medium","house_position":false,"article":"kb-environment-heat-light-stress","sources":["Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020","Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x"]},{"id":"cause-light-stress-photoinhibition","label":"Light burn: too much light for the plant's climate and CO2","kind":"light","base_rate":"common","symptoms":{"sym-taco-leaves":"hallmark","sym-canoe-edges-up":"typical","sym-crispy-top-leaves":"typical","sym-bleached-top-leaves":"typical","sym-compact-small-leaves":"possible","sym-pistils-brown-early":"possible"},"contexts":{"top_only":{"yes":"higher","no":"lower"},"recent_changes":{"light_change":"higher"},"stage":{"seedling":"higher","clone":"higher"},"readings":{"ppfd_high":"higher","vpd_high":"higher","ppfd_low":"lower"}},"rule_out_first":["cause-heat-stress","cause-high-vpd-low-rh"],"distinguishing_questions":["q-top-only","q-ppfd","q-leaf-temp","q-vpd"],"tests":["test-ppfd-meter","test-leaf-temperature"],"fix":"Dim or raise the light 10-20%; ramp intensity over 7-10 days after a light change. Seedlings and clones need only 100-300 µmol/m²/s. High PPFD works only with leaf temperature, VPD, roots and feed all in range.","confirm":"Top leaves flatten within 1-3 days.","urgency":"medium","house_position":false,"article":"kb-environment-heat-light-stress","sources":["Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020","Nelson JA, Bugbee B. 2015. Analysis of environmental effects on leaf temperature under sunlight, high pressure sodium and light emitting diodes. PLoS ONE 10(10):e0138930. https://doi.org/10.1371/journal.pone.0138930"]},{"id":"cause-low-light","label":"Not enough light","kind":"light","base_rate":"common","symptoms":{"sym-stretchy":"hallmark","sym-leggy-seedling":"hallmark","sym-weak-stems":"typical","sym-airy-buds":"typical","sym-whole-plant-pale":"possible","sym-stunted":"typical","sym-excess-flower-stretch":"possible"},"contexts":{"light_type":{"fluorescent":"higher","sun":"lower"},"readings":{"ppfd_low":"higher","ppfd_high":"lower"},"stage":{"seedling":"higher"}},"rule_out_first":["cause-heat-stress","cause-normal-flower-stretch"],"distinguishing_questions":["q-ppfd","q-light-type","q-stage"],"tests":["test-ppfd-meter"],"fix":"Bring PPFD to stage targets: seedlings 100-300, veg 300-700, flower 800-1,200 µmol/m²/s. Yield rose linearly with PPFD from 120 to 1,800 in a controlled trial. Lower canopy buds under ~300-400 µmol/m²/s make larf: thin or lollipop the shaded bottom, or train flat.","confirm":"New internodes shorten within a week; denser buds on the following weeks of growth.","urgency":"low","house_position":false,"article":"kb-diagnosis-stretching","sources":["Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020"]},{"id":"cause-light-leak","label":"Light leak or interrupted dark period","kind":"light","base_rate":"common","symptoms":{"sym-flowering-delayed":"hallmark","sym-reveg-in-flower":"typical","sym-nanners":"typical","sym-pollen-sacs":"typical","sym-single-blade-leaves":"typical","sym-foxtails":"possible"},"contexts":{"light_schedule":{"leak_or_interrupt":"higher","irregular":"higher","flower_12":"lower"},"plant_type":{"autoflower":"lower"},"stage":{"early_flower":"higher","late_flower":"higher","veg":"lower"}},"rule_out_first":["cause-genetic-late-flowering","cause-herm-genetic"],"distinguishing_questions":["q-light-schedule","q-plant-type","q-stage"],"tests":["test-light-leak-check"],"fix":"Seal the dark period: pinholes, zips, vents and equipment LEDs (tape them), and check the timer. Even dim night light can delay flowering in sensitive cultivars and reveal herm-prone genetics. Use a green headlamp only for brief checks.","confirm":"Flowering resumes within 1-2 weeks; no new single-blade leaves.","urgency":"high","house_position":true,"article":"kb-environment-photoperiod-light-leaks","sources":["Eckels M, Bugbee B. 2024. Night light pollution delays flowering in soybean and cannabis (ASHS 2024 conference abstract). https://ashs2024.sched.com/event/1dtbo/ce-4-night-light-pollution-delays-flowering-in-soybean-and-cannabis","Punja ZK, Holmes JE. 2020. Hermaphroditism in marijuana (Cannabis sativa L.) inflorescences: impact on floral morphology, seed formation, progeny sex ratios, and genetic variation. Frontiers in Plant Science 11:718. https://doi.org/10.3389/fpls.2020.00718"]},{"id":"cause-reveg","label":"Re-vegetation from too-long days in flower","kind":"light","base_rate":"uncommon","symptoms":{"sym-reveg-in-flower":"hallmark","sym-single-blade-leaves":"hallmark","sym-buds-stall":"typical"},"contexts":{"light_schedule":{"leak_or_interrupt":"higher","irregular":"higher"},"stage":{"early_flower":"higher","late_flower":"higher"},"plant_type":{"autoflower":"lower"}},"rule_out_first":["cause-light-leak"],"distinguishing_questions":["q-light-schedule","q-plant-type"],"tests":["test-light-leak-check"],"fix":"Restore an uninterrupted 12-13 h dark period (13/11 is fine; some cultivars flower at 14-15 h days with ramps). Outdoors, early-season plants under long days re-veg; plant later or use light deprivation.","confirm":"No new single-blade growth within 2 weeks.","urgency":"medium","house_position":false,"article":"kb-answers-how-to-reveg-a-plant","sources":["Peterswald TJ, Mieog JC, Azman Halimi R, et al. 2023. Moving away from 12:12; the effect of different photoperiods on biomass yield and cannabinoids in medicinal cannabis. Plants 12(5):1061. https://doi.org/10.3390/plants12051061","Eckels M, Bugbee B. 2024. Night light pollution delays flowering in soybean and cannabis (ASHS 2024 conference abstract). https://ashs2024.sched.com/event/1dtbo/ce-4-night-light-pollution-delays-flowering-in-soybean-and-cannabis"]},{"id":"cause-foxtail-stress","label":"Heat or light stress foxtailing on the top colas","kind":"light","base_rate":"common","symptoms":{"sym-foxtails":"hallmark","sym-bleached-top-leaves":"typical","sym-pistils-brown-early":"possible"},"contexts":{"top_only":{"yes":"higher","no":"lower"},"stage":{"late_flower":"higher"},"readings":{"ppfd_high":"higher","temp_high":"higher"}},"rule_out_first":["cause-genetic-foxtailing"],"distinguishing_questions":["q-top-only","q-ppfd","q-leaf-temp","q-cultivar-purple"],"tests":["test-ppfd-meter","test-leaf-temperature","test-sibling-compare"],"fix":"Lower top-cola PPFD and leaf temperature (leaf under ~28-30 °C / 82-86 °F); even out the canopy. Evidence is mostly grower observation.","confirm":"No new spires on top colas over the next week.","urgency":"low","house_position":false,"article":"kb-diagnosis-foxtails","sources":["Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020","Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x"]},{"id":"cause-heat-stress","label":"Heat stress","kind":"environment","base_rate":"very_common","symptoms":{"sym-bud-tips-burnt":"typical","sym-new-growth-limp":"possible","sym-taco-leaves":"hallmark","sym-canoe-edges-up":"typical","sym-crispy-top-leaves":"typical","sym-midday-wilt":"typical","sym-foxtails":"typical","sym-pistils-brown-early":"possible","sym-margins-roll-under":"possible","sym-airy-buds":"possible","sym-nanners":"rare"},"contexts":{"recent_changes":{"heat_event":"higher"},"light_type":{"hps_mh":"higher"},"readings":{"temp_high":"higher","vpd_high":"higher","temp_low":"lower"},"top_only":{"yes":"higher"}},"rule_out_first":["cause-light-stress-photoinhibition","cause-underwatering","cause-hot-reservoir"],"distinguishing_questions":["q-air-temp","q-leaf-temp","q-top-only","q-light-type","q-recent-changes"],"tests":["test-leaf-temperature","test-hygrometer-check"],"fix":"Bring canopy leaf temperature under about 30 °C (86 °F): more exhaust (one tent air exchange every 1-3 minutes), raise or dim the light, add canopy airflow (0.3-1.0 m/s), keep RH so VPD stays 1.0-1.5 kPa, water well. Above ~30 °C photosynthesis falls unless CO2 and light are high.","confirm":"Leaves flatten within a day; no new foxtails or crisping.","urgency":"high","house_position":false,"article":"kb-environment-heat-light-stress","sources":["Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x","Nelson JA, Bugbee B. 2015. Analysis of environmental effects on leaf temperature under sunlight, high pressure sodium and light emitting diodes. PLoS ONE 10(10):e0138930. https://doi.org/10.1371/journal.pone.0138930","Greenhouse Grower. How environmental stresses can impact cannabinoid production (report on Colorado State University heat-stress work). https://www.greenhousegrower.com/?p=159152"]},{"id":"cause-cold-stress","label":"Cold stress","kind":"environment","base_rate":"uncommon","symptoms":{"sym-purple-veins":"typical","sym-purple-stems":"typical","sym-purple-leaves":"typical","sym-dark-dull-purple-blotch":"typical","sym-stunted":"typical","sym-compact-small-leaves":"possible","sym-leaf-drop-sudden":"rare","sym-oedema-bumps":"possible"},"contexts":{"recent_changes":{"cold_event":"higher"},"readings":{"temp_low":"higher","night_cold":"higher","temp_high":"lower"},"cultivar_purple":{"known_purple":"lower"}},"rule_out_first":["cause-genetic-anthocyanin","cause-cold-root-zone"],"distinguishing_questions":["q-night-temp","q-air-temp","q-cultivar-purple"],"tests":["test-hygrometer-check"],"fix":"Keep days at 22-28 °C (72-82 °F) and nights no more than 3-6 °C (5-10 °F) cooler and above ~15 °C (59 °F); warm the root zone. Cold-for-colour is real in purple cultivars, but claims of more terpenes or resin are unsupported.","confirm":"Growth resumes within a week; new leaves come in green.","urgency":"medium","house_position":true,"article":"kb-answers-how-cold-is-too-cold","sources":["Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x","Kim SR, Basnet P, Kovaleski AP, Ellison SL. 2025. Anthocyanin accumulation, inflorescence dry weight and total cannabidiol content have different temperature optima in Cannabis sativa. Journal of Cannabis Research 7:51. https://doi.org/10.1186/s42238-025-00311-w"]},{"id":"cause-low-vpd-high-rh","label":"Humidity too high / VPD too low","kind":"environment","base_rate":"common","symptoms":{"sym-condensation":"hallmark","sym-rust-spots-new":"possible","sym-oedema-bumps":"typical","sym-white-powder":"possible","sym-grey-fuzz":"possible","sym-musty-smell":"typical","sym-medium-stays-wet":"typical","sym-curl-down-wet":"possible","sym-water-soaked-lesions":"possible"},"contexts":{"rh":{"very_high":"higher","high":"higher","low":"lower","very_low":"lower"},"stage":{"late_flower":"higher","early_flower":"higher"},"readings":{"rh_high":"higher","vpd_low":"higher","rh_low":"lower"}},"rule_out_first":["cause-overwatering"],"distinguishing_questions":["q-rh","q-vpd","q-stage"],"tests":["test-hygrometer-check"],"fix":"Target about 55-70% RH in veg, 50-60% early flower, 40-50% late flower (leaf VPD 1.0-1.5 kPa in flower). Dehumidify, raise exhaust, keep air moving under the canopy and watch the lights-off spike (dew point). High RH in flower raised bud-rot risk and in one study delayed flowering and lowered cannabinoids.","confirm":"RH holds in band through lights-off for 3+ days; no new mould signs.","urgency":"high","house_position":false,"article":"kb-environment-humidity-by-stage","sources":["Corredor-Perilla IC, Kwon H, Park J. 2025. High relative humidity in cannabis cultivation. Frontiers in Plant Science 16:1678142. https://doi.org/10.3389/fpls.2025.1678142","Punja ZK. 2021. Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science 77:3857-3870. https://pmc.ncbi.nlm.nih.gov/articles/PMC8451794/"]},{"id":"cause-high-vpd-low-rh","label":"Air too dry / VPD too high","kind":"environment","base_rate":"common","symptoms":{"sym-taco-leaves":"typical","sym-canoe-edges-up":"typical","sym-burnt-tips":"possible","sym-midday-wilt":"typical","sym-clone-wilting":"typical","sym-crispy-top-leaves":"possible"},"contexts":{"rh":{"very_low":"higher","low":"higher","high":"lower","very_high":"lower"},"stage":{"clone":"higher","seedling":"higher"},"readings":{"rh_low":"higher","vpd_high":"higher","temp_high":"higher"}},"rule_out_first":["cause-heat-stress","cause-underwatering"],"distinguishing_questions":["q-rh","q-vpd","q-air-temp","q-stage"],"tests":["test-hygrometer-check","test-leaf-temperature"],"fix":"Raise RH or lower temperature to bring leaf VPD to 0.4-0.8 kPa (clones, seedlings), 0.8-1.2 (veg), 1.0-1.5 (flower). Humidifier, less exhaust when cool, fewer dry hot air inputs. Dry air also speeds spider mites.","confirm":"Leaves flatten within a day.","urgency":"medium","house_position":false,"article":"kb-environment-vpd-explained","sources":["Nelson JA, Bugbee B. 2015. Analysis of environmental effects on leaf temperature under sunlight, high pressure sodium and light emitting diodes. PLoS ONE 10(10):e0138930. https://doi.org/10.1371/journal.pone.0138930","Allen RG, Pereira LS, Raes D, Smith M. 1998. Crop evapotranspiration: guidelines for computing crop water requirements (FAO Irrigation and Drainage Paper 56), Chapter 3. https://www.fao.org/4/x0490e/x0490e07.htm"]},{"id":"cause-wind-burn","label":"Wind burn from a fan blowing directly on leaves","kind":"environment","base_rate":"common","symptoms":{"sym-wind-burn":"hallmark","sym-damage-one-side":"hallmark","sym-clawing-dark":"possible","sym-canoe-edges-up":"possible","sym-burnt-tips":"possible"},"contexts":{"where_first":{"random":"higher"},"readings":{"rh_low":"higher"}},"rule_out_first":["cause-heat-stress","cause-overfeeding"],"distinguishing_questions":["q-where-first","q-rh"],"tests":["test-sibling-compare"],"fix":"Aim fans across and under the canopy, not straight at leaves: leaves should rustle, not thrash (roughly 0.3-1.0 m/s at leaf level). Damaged leaves stay damaged. Cannabis-specific evidence is grower observation.","confirm":"No new damage on the fan side within a week.","urgency":"low","house_position":false,"article":"kb-environment-airflow","sources":["Kitaya Y, Tsuruyama J, Shibuya T, Yoshida M, Kiyota M. 2003. Effects of air current speed on gas exchange in plant leaves and plant canopies. Advances in Space Research 31(1):177-182. https://doi.org/10.1016/S0273-1177(02)00747-0"]},{"id":"cause-co2-depletion","label":"CO2 depleted in a sealed room without enrichment","kind":"environment","base_rate":"rare","symptoms":{"sym-stunted":"typical","sym-airy-buds":"possible"},"contexts":{"readings":{"co2_low":"higher"}},"rule_out_first":["cause-low-light","cause-underfeeding"],"distinguishing_questions":["q-co2","q-ppfd"],"tests":["test-co2-check"],"fix":"Exchange air (exhaust with passive or active intake) or enrich to 800-1,200 ppm during lights-on when PPFD is above ~900 µmol/m²/s and the room is sealed.","confirm":"Lights-on CO2 holds above ~400 ppm; growth rate returns.","urgency":"low","house_position":false,"article":"kb-environment-co2-enrichment","sources":["Chandra S, Lata H, Khan IA, ElSohly MA. 2008. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions. Physiology and Molecular Biology of Plants 14(4):299-306. https://doi.org/10.1007/s12298-008-0027-x","Chandra S, Lata H, Khan IA, ElSohly MA. 2011. Photosynthetic response of Cannabis sativa L., an important medicinal plant, to elevated levels of CO2. Physiology and Molecular Biology of Plants 17:291-295. https://doi.org/10.1007/s12298-011-0066-6"]},{"id":"cause-co2-excess","label":"CO2 set far too high","kind":"environment","base_rate":"rare","symptoms":{"sym-margins-roll-under":"typical","sym-compact-small-leaves":"rare"},"contexts":{"readings":{"co2_high":"higher"}},"rule_out_first":["cause-heat-stress","cause-light-stress-photoinhibition"],"distinguishing_questions":["q-co2","q-air-temp"],"tests":["test-co2-check"],"fix":"Hold 800-1,200 ppm; above that there is little further gain in cannabis. Leaf rolling and chlorosis at very high CO2 are documented in tomato and other greenhouse crops. People: keep occupied rooms under the 5,000 ppm 8-hour limit and never enter a room above 30,000 ppm.","confirm":"Symptoms stop on new growth after CO2 is lowered.","urgency":"medium","house_position":false,"article":"kb-environment-co2-enrichment","sources":["Chandra S, Lata H, Khan IA, ElSohly MA. 2011. Photosynthetic response of Cannabis sativa L., an important medicinal plant, to elevated levels of CO2. Physiology and Molecular Biology of Plants 17:291-295. https://doi.org/10.1007/s12298-011-0066-6","NIOSH Pocket Guide to Chemical Hazards: Carbon dioxide (REL 5,000 ppm TWA; ST 30,000 ppm; IDLH 40,000 ppm). https://www.cdc.gov/niosh/npg/npgd0103.html"]},{"id":"cause-oedema","label":"Oedema (water uptake outrunning transpiration)","kind":"environment","base_rate":"rare","symptoms":{"sym-oedema-bumps":"hallmark","sym-curl-down-wet":"possible"},"contexts":{"rh":{"very_high":"higher","high":"higher"},"readings":{"vpd_low":"higher","temp_low":"higher"},"watering_frequency":{"before_dry":"higher"}},"rule_out_first":["cause-spider-mites","cause-thrips","cause-overwatering"],"distinguishing_questions":["q-rh","q-watering-frequency","q-magnifier-underside"],"tests":["test-magnifier","test-hygrometer-check"],"fix":"Lower RH and keep air moving, water in the morning or at lights-on, and avoid watering cold, wet pots. Documented in many greenhouse crops; cannabis reports are anecdotal.","confirm":"No new blisters on new leaves within a week.","urgency":"low","house_position":false,"article":"kb-diagnosis-spots-necrosis-decision-tree","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-clone-humidity-loss","label":"Cuttings losing water faster than they can root","kind":"environment","base_rate":"common","symptoms":{"sym-clone-wilting":"hallmark","sym-yellow-lower-leaves":"possible"},"contexts":{"stage":{"clone":"higher","veg":"lower","early_flower":"lower","late_flower":"lower"},"rh":{"very_low":"higher","low":"higher"},"readings":{"vpd_high":"higher","temp_high":"higher","ppfd_high":"higher"}},"rule_out_first":["cause-damping-off","cause-root-rot-pythium"],"distinguishing_questions":["q-stage","q-rh","q-ppfd"],"tests":["test-hygrometer-check","test-ppfd-meter"],"fix":"Keep clones at about 75-90% RH (VPD ~0.4-0.8 kPa), 22-26 °C (72-79 °F), PPFD 100-200 µmol/m²/s; trim large fan leaves by half; vent the dome gradually only once roots show.","confirm":"Cuttings stand up within 24 h; roots in 7-14 days.","urgency":"medium","house_position":false,"article":"kb-answers-why-are-my-clones-wilting","sources":["Michigan State University. Lighting of cuttings (rooting-phase PPFD). https://www.canr.msu.edu/uploads/resources/pdfs/lighting-of-cuttings.pdf"]},{"id":"cause-auto-stress-stunting","label":"Autoflower stunted by early stress","kind":"environment","base_rate":"common","symptoms":{"sym-auto-small":"hallmark","sym-stunted":"typical","sym-seedling-stalled":"typical"},"contexts":{"plant_type":{"autoflower":"higher","photoperiod":"lower"},"recent_changes":{"transplant":"higher","trained":"higher"},"pot_size":{"too_small":"higher","too_big":"higher"},"watering_frequency":{"before_dry":"higher"},"readings":{"ppfd_low":"higher"}},"rule_out_first":["cause-overwatering","cause-low-light","cause-transplant-shock"],"distinguishing_questions":["q-plant-type","q-recent-changes","q-watering-frequency","q-ppfd","q-pot-size"],"tests":["test-lift-pot","test-ppfd-meter"],"fix":"Autos run on a countdown from germination, so lost growth never returns. Next run: sow straight into the final 11-19 L (3-5 gal) pot, never transplant, water seedlings in small rings, give 300-600+ µmol/m²/s early, train with LST only (topping never matches proper LST). This run: keep conditions steady and feed well; don't add more stress.","confirm":"Steady weekly growth from here on; size gap to siblings stops widening.","urgency":"medium","house_position":true,"article":"kb-answers-why-is-my-autoflower-small","sources":["Poorter H, Buhler J, van Dusschoten D, Climent J, Postma JA. 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth. Functional Plant Biology 39(11):839-850. https://doi.org/10.1071/FP12049","GenetixBay house position (founder): autoflowers run on a strict countdown; transplanting is almost a no-no and topping never matches proper LST. See kb-basics-photoperiod-vs-autoflower."]},{"id":"cause-spider-mites","label":"Twospotted spider mites","kind":"pest","base_rate":"very_common","symptoms":{"sym-stippling":"hallmark","sym-webbing":"hallmark","sym-moving-dots-underside":"hallmark","sym-yellow-lower-leaves":"possible","sym-bronze-leaves":"possible","sym-rust-spots-new":"possible","sym-whole-plant-pale":"possible"},"contexts":{"magnifier_underside":{"moving_dots":"higher","webbing":"higher","nothing":"lower"},"rh":{"very_low":"higher","low":"higher","very_high":"lower"},"recent_changes":{"new_plants":"higher"},"spread":{"spreading":"higher"},"readings":{"temp_high":"higher","rh_low":"higher"}},"rule_out_first":["cause-ca-deficiency","cause-thrips"],"distinguishing_questions":["q-magnifier-underside","q-rh","q-recent-changes","q-spread"],"tests":["test-magnifier","test-white-paper-tap"],"fix":"Act now: they breed fastest hot and dry. Remove the worst leaves into a sealed bag, cool the room and raise RH a little (in veg), release predatory mites (Phytoseiulus persimilis for hot spots, Neoseiulus californicus as a preventive) before numbers explode. Soaps or horticultural oils only in veg, never on buds. Quarantine new clones.","confirm":"No new stippling on new leaves and no live mites at 10-20x after 7-14 days.","urgency":"high","house_position":false,"article":"kb-pests-spider-mites","sources":["UC IPM. Pest Notes: Spider Mites (Publication 7405). https://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html","Utah State University Extension. Two-Spotted Spider Mite (hemp). https://extension.usu.edu/planthealth/ipm/notes_ag/hemp-spider-mites.php"]},{"id":"cause-broad-mites","label":"Broad mites","kind":"pest","base_rate":"uncommon","symptoms":{"sym-glossy-hardened-tips":"hallmark","sym-twisted-new-growth":"hallmark","sym-bronze-leaves":"typical","sym-dying-growing-tips":"possible","sym-small-narrow-new-leaves":"possible","sym-stunted":"typical"},"contexts":{"magnifier_underside":{"glassy_specks":"higher","nothing":"lower"},"recent_changes":{"new_plants":"higher"},"spread":{"spreading":"higher","all_plants":"lower"},"calmag":{"yes":"lower"}},"rule_out_first":["cause-heat-stress","cause-ca-deficiency","cause-b-deficiency"],"distinguishing_questions":["q-magnifier-underside","q-recent-changes","q-spread"],"tests":["test-magnifier","test-response-to-fix"],"fix":"Confirm at 30-60x. Remove and bag heavily infested plants; mothers and clones are the usual source. Release predatory mites (e.g. Neoseiulus californicus or Amblyseius swirskii) on the rest, keep tools and clothes clean, quarantine new stock. In flower, removal is usually the only clean option.","confirm":"New growth expands normally (not glossy or twisted) within 10-14 days.","urgency":"high","house_position":false,"article":"kb-pests-broad-russet-mites","sources":["UConn IPM. Managing Broad Mites on Greenhouse Crops. https://ipm.cahnr.uconn.edu/ipm-managing-broad-mites-on-greenhouse-crops","Virginia Cooperative Extension. Broad mite (ENTO-587). https://pubs.ext.vt.edu/content/pubs_ext_vt_edu/en/ENTO/ento-587/ento-587.html"]},{"id":"cause-russet-mites","label":"Hemp russet mites","kind":"pest","base_rate":"uncommon","symptoms":{"sym-bronze-leaves":"hallmark","sym-canoe-edges-up":"typical","sym-yellow-lower-leaves":"possible","sym-brittle-stems":"rare","sym-stunted":"typical"},"contexts":{"magnifier_underside":{"glassy_specks":"higher","nothing":"lower"},"recent_changes":{"new_plants":"higher"},"spread":{"spreading":"higher"}},"rule_out_first":["cause-k-deficiency","cause-heat-stress","cause-mg-deficiency"],"distinguishing_questions":["q-magnifier-underside","q-recent-changes","q-where-first"],"tests":["test-magnifier"],"fix":"Confirm at 30-60x (they look like moving dust). Remove badly infested plants; release predatory mites preventively; quarantine clones; leave a plant-free gap between cycles.","confirm":"Bronzing stops climbing and no live mites at 30-60x in 2 weeks.","urgency":"high","house_position":false,"article":"kb-pests-broad-russet-mites","sources":["NC State Extension. Hemp Russet Mite in Industrial Hemp. https://content.ces.ncsu.edu/hemp-russet-mite-in-industrial-hemp","UConn IPM. Managing Broad Mites on Greenhouse Crops. https://ipm.cahnr.uconn.edu/ipm-managing-broad-mites-on-greenhouse-crops"]},{"id":"cause-thrips","label":"Thrips","kind":"pest","base_rate":"common","symptoms":{"sym-thrips-frass":"hallmark","sym-silvering":"hallmark","sym-stippling":"typical","sym-white-sparkle-trichomes":"rare","sym-twisted-new-growth":"possible"},"contexts":{"magnifier_underside":{"slender_insects":"higher","nothing":"lower"},"flying_insects":{"slender_winged":"higher"},"recent_changes":{"new_plants":"higher"}},"rule_out_first":["cause-spider-mites","cause-spray-burn"],"distinguishing_questions":["q-magnifier-underside","q-flying-insects","q-recent-changes"],"tests":["test-magnifier","test-white-paper-tap","test-sticky-cards"],"fix":"Two levels: predatory mites (Neoseiulus cucumeris, Amblyseius swirskii) or Orius on the foliage, plus soil predators (Stratiolaelaps scimitus) or Steinernema nematodes in the medium where they pupate. Blue or yellow cards to monitor. Sprays only in veg.","confirm":"Card counts fall and no new silvering on new leaves within 2-3 weeks.","urgency":"medium","house_position":false,"article":"kb-pests-thrips","sources":["UC IPM. Pest Notes: Thrips (Publication 7429). https://ipm.ucanr.edu/PMG/PESTNOTES/pn7429.html","UConn IPM. Biological Control of Western Flower Thrips. https://ipm.cahnr.uconn.edu/ipm-biological-control-of-western-flower-thrips/"]},{"id":"cause-aphids","label":"Aphids","kind":"pest","base_rate":"common","symptoms":{"sym-aphid-clusters":"hallmark","sym-white-cast-skins":"hallmark","sym-sticky-honeydew":"typical","sym-sooty-mould":"possible","sym-ants":"typical","sym-twisted-new-growth":"possible","sym-yellow-new-growth":"possible"},"contexts":{"magnifier_underside":{"soft_insects":"higher"},"sticky":{"yes":"higher"},"recent_changes":{"new_plants":"higher"}},"rule_out_first":["cause-whiteflies","cause-mealybugs"],"distinguishing_questions":["q-magnifier-underside","q-sticky","q-flying-insects"],"tests":["test-magnifier","test-sticky-cards"],"fix":"Squash or rinse small colonies; release parasitoid wasps (Aphidius), predatory midges or lacewings; insecticidal soap or oil only before flower. Control ants that farm them.","confirm":"Colonies shrink and mummified (parasitised) aphids appear within 1-2 weeks.","urgency":"medium","house_position":false,"article":"kb-pests-aphids","sources":["UC IPM. Pest Notes: Aphids (Publication 7404). https://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html","NC State Extension. Cannabis Aphid in Industrial Hemp. https://content.ces.ncsu.edu/cannabis-aphid-in-industrial-hemp"]},{"id":"cause-root-aphids","label":"Root aphids","kind":"pest","base_rate":"uncommon","symptoms":{"sym-root-aphids":"hallmark","sym-stunted":"typical","sym-wilt-moist-not-recovering":"typical","sym-yellow-lower-leaves":"typical","sym-one-plant-stunted":"possible"},"contexts":{"medium":{"soil":"higher","coco":"higher","living_soil":"higher","water":"lower"},"recent_changes":{"new_plants":"higher"},"root_colour":{"white":"higher"}},"rule_out_first":["cause-overwatering","cause-n-deficiency","cause-root-rot-pythium"],"distinguishing_questions":["q-root-colour","q-recent-changes","q-flying-insects"],"tests":["test-root-ball-insects","test-sticky-cards"],"fix":"Confirm on the roots. Apply soil-dwelling biologicals (Beauveria bassiana drenches, Stratiolaelaps scimitus, Steinernema or Heterorhabditis nematodes), sanitise, and leave a plant-free gap between cycles; dispose of infested media.","confirm":"No live aphids on root checks after 2-3 weeks; growth resumes.","urgency":"high","house_position":false,"article":"kb-pests-root-aphids","sources":["Cranshaw W, Wainwright-Evans S. 2020. Cannabis sativa as a host of rice root aphid (Hemiptera: Aphididae) in North America. Journal of Integrated Pest Management 11(1):15. https://doi.org/10.1093/jipm/pmaa010","Utah State University Extension. Rice Root Aphids (hemp). https://extension.usu.edu/planthealth/ipm/notes_ag/hemp-rice-root-aphid"]},{"id":"cause-fungus-gnats","label":"Fungus gnats","kind":"pest","base_rate":"very_common","symptoms":{"sym-gnats-flying":"hallmark","sym-larvae-in-medium":"hallmark","sym-seedling-stalled":"possible","sym-clone-wilting":"possible","sym-damping-off":"possible"},"contexts":{"watering_frequency":{"before_dry":"higher"},"flying_insects":{"small_black_flies":"higher"},"medium":{"soil":"higher","living_soil":"higher","coco":"higher","water":"lower"},"stage":{"seedling":"higher","clone":"higher"}},"rule_out_first":["cause-overwatering"],"distinguishing_questions":["q-flying-insects","q-watering-frequency","q-medium"],"tests":["test-sticky-cards","test-potato-slice"],"fix":"Fix the watering first: let the top 2-3 cm dry. Then Bti drenches (larvicide), Steinernema feltiae nematodes or Stratiolaelaps mites; yellow cards for adults. Larvae chew seedling and clone roots and can open the door to Pythium.","confirm":"Card catches fall within 2-3 weeks; no larvae under potato slices.","urgency":"low","house_position":false,"article":"kb-pests-fungus-gnats","sources":["UC IPM. Pest Notes: Fungus Gnats (Publication 7448). https://ipm.ucanr.edu/legacy_assets/pdf/pestnotes/pnfungusgnats.pdf","UConn IPM. Managing Fungus Gnats in the Greenhouse. https://ipm.cahnr.uconn.edu/managing-fungus-gnats-in-the-greenhouse/"]},{"id":"cause-whiteflies","label":"Whiteflies","kind":"pest","base_rate":"uncommon","symptoms":{"sym-whiteflies":"hallmark","sym-sticky-honeydew":"typical","sym-sooty-mould":"typical","sym-stippling":"possible","sym-yellow-lower-leaves":"possible"},"contexts":{"flying_insects":{"white_flies":"higher"},"magnifier_underside":{"white_flies":"higher"},"sticky":{"yes":"higher"}},"rule_out_first":["cause-aphids"],"distinguishing_questions":["q-flying-insects","q-sticky","q-magnifier-underside"],"tests":["test-sticky-cards","test-magnifier"],"fix":"Yellow cards; identify the species; release Encarsia formosa (greenhouse whitefly) or Eretmocerus (warmer rooms, silverleaf whitefly) plus predatory mites; keep sprays out of flower.","confirm":"Card counts fall within 3-4 weeks; parasitised black nymphs appear.","urgency":"medium","house_position":false,"article":"kb-pests-whiteflies","sources":["UC IPM. Pest Notes: Whiteflies (Publication 7401). https://ipm.ucanr.edu/PMG/PESTNOTES/pn7401.html"]},{"id":"cause-caterpillars","label":"Caterpillars and budworms","kind":"pest","base_rate":"common","symptoms":{"sym-caterpillars-visible":"hallmark","sym-frass-in-buds":"hallmark","sym-holes-in-leaves":"typical","sym-bud-brown-inside":"typical"},"contexts":{"light_type":{"sun":"higher"},"flying_insects":{"moths":"higher"},"stage":{"early_flower":"higher","late_flower":"higher"}},"rule_out_first":["cause-botrytis"],"distinguishing_questions":["q-flying-insects","q-light-type","q-stage"],"tests":["test-bud-inspection"],"fix":"Hand-pick; exclude moths with netting; use Bt (kurstaki or aizawai) while larvae are small, since it must be eaten and breaks down in sunlight in days. Remove bored buds: frass starts bud rot.","confirm":"No fresh frass or holes after 1 week.","urgency":"high","house_position":false,"article":"kb-pests-caterpillars","sources":["Oregon State University Extension. Corn earworm management in hemp (EM 9626). https://extension.oregonstate.edu/catalog/em-9626-corn-earworm-management-hemp"]},{"id":"cause-mealybugs","label":"Mealybugs","kind":"pest","base_rate":"rare","symptoms":{"sym-white-cottony-clumps":"hallmark","sym-sticky-honeydew":"typical","sym-sooty-mould":"possible","sym-root-aphids":"rare"},"contexts":{"sticky":{"yes":"higher"},"recent_changes":{"new_plants":"higher"}},"rule_out_first":["cause-aphids","cause-root-aphids"],"distinguishing_questions":["q-sticky","q-recent-changes"],"tests":["test-magnifier"],"fix":"Remove colonies with a cotton bud dipped in 70% isopropyl alcohol (veg only, test a leaf first); release mealybug predators (e.g. Cryptolaemus beetles) or parasitoids; quarantine new stock; discard heavily infested plants.","confirm":"No new cottony clusters after 2 weeks.","urgency":"medium","house_position":false,"article":"kb-pests-mealybugs","sources":["UC IPM. Pest Notes: Mealybugs (Publication 74174). https://ipm.ucanr.edu/PMG/PESTNOTES/pn74174.html"]},{"id":"cause-leafminers","label":"Leafminers","kind":"pest","base_rate":"rare","symptoms":{"sym-leaf-trails":"hallmark"},"contexts":{"light_type":{"sun":"higher"}},"rule_out_first":[],"distinguishing_questions":["q-light-type"],"tests":["test-magnifier"],"fix":"Pinch mined leaflets and the larva inside; yellow cards for adults; parasitoid wasps (e.g. Diglyphus) in greenhouses. Cosmetic in light infestations.","confirm":"No new mines after 2 weeks.","urgency":"low","house_position":false,"article":"kb-diagnosis-spots-necrosis-decision-tree","sources":["UC IPM. Pest Notes: Leafminers (Publication 74166). https://ipm.ucanr.edu/PMG/PESTNOTES/pn74166.html"]},{"id":"cause-powdery-mildew","label":"Powdery mildew","kind":"disease","base_rate":"very_common","symptoms":{"sym-white-powder":"hallmark","sym-powder-on-buds":"hallmark","sym-yellow-lower-leaves":"rare"},"contexts":{"wipe_test":{"wipes_returns":"higher","wipes_stays_gone":"lower","no_wipe":"lower"},"rh":{"high":"higher","very_high":"higher"},"recent_changes":{"new_plants":"higher"},"spread":{"spreading":"higher"},"readings":{"rh_high":"higher","vpd_low":"higher"}},"rule_out_first":["cause-spray-residue","cause-normal-trichomes"],"distinguishing_questions":["q-wipe-test","q-rh","q-recent-changes"],"tests":["test-wipe","test-hygrometer-check"],"fix":"Treat early in veg: remove the worst leaves into a bag, improve airflow and stable humidity (avoid big day-night RH swings), and use least-toxic contact options (e.g. potassium bicarbonate, sulfur, or biological products, in veg only; never sulfur near oils or in flower). Once it reaches flowers there is no clean fix. Choose resistant genetics and clean clones.","confirm":"No new colonies on treated or new leaves within 7-10 days.","urgency":"high","house_position":false,"article":"kb-diseases-powdery-mildew","sources":["Punja ZK, et al. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://doi.org/10.3389/fpls.2019.01120","Pacific Northwest Plant Disease Management Handbook. Hemp (Cannabis sativa) - Powdery Mildew. https://pnwhandbooks.org/plantdisease/host-disease/hemp-cannabis-sativa-powdery-mildew"]},{"id":"cause-botrytis","label":"Botrytis bud rot (grey mould)","kind":"disease","base_rate":"common","symptoms":{"sym-condensation":"possible","sym-bud-rot-dead-leaf":"hallmark","sym-bud-brown-inside":"hallmark","sym-grey-fuzz":"hallmark","sym-musty-smell":"typical","sym-stem-cankers":"typical","sym-water-soaked-lesions":"possible"},"contexts":{"stage":{"late_flower":"higher","early_flower":"higher","veg":"lower","seedling":"lower"},"rh":{"high":"higher","very_high":"higher","low":"lower"},"readings":{"rh_high":"higher","vpd_low":"higher","night_cold":"higher"}},"rule_out_first":["cause-caterpillars"],"distinguishing_questions":["q-stage","q-rh","q-night-temp"],"tests":["test-bud-inspection","test-hygrometer-check"],"fix":"Act now. Bag infected buds before cutting them out, 3-5 cm (1-2 in) past visible rot, and clean tools; never shake them. Drop RH to about 40-50% in late flower, control the lights-off dew point, move air through dense colas. There is no cure in flower; consider harvesting early if it keeps spreading.","confirm":"No new rot on weekly cola checks for 2 weeks.","urgency":"critical","house_position":false,"article":"kb-diseases-botrytis-bud-rot","sources":["Punja ZK, et al. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://doi.org/10.3389/fpls.2019.01120","Utah State University Extension. Hemp bud rot (IPM Notes). https://extension.usu.edu/planthealth/ipm/notes_ag/hemp-bud-rot"]},{"id":"cause-root-rot-pythium","label":"Root rot (Pythium)","kind":"disease","base_rate":"common","symptoms":{"sym-plant-not-drinking":"typical","sym-roots-brown-slimy":"hallmark","sym-root-zone-smell":"typical","sym-wilt-moist-not-recovering":"hallmark","sym-sudden-yellowing":"typical","sym-yellow-lower-leaves":"typical","sym-stunted":"typical","sym-reservoir-cloudy":"possible","sym-ph-falling":"possible","sym-damping-off":"possible","sym-stem-base-rot":"possible"},"contexts":{"system":{"dwc":"higher","recirc":"higher","nft":"higher","aero_lpa":"higher","kratky":"higher"},"medium":{"water":"higher"},"root_colour":{"brown_slimy":"higher","white":"lower","tan_firm":"lower"},"root_smell":{"yes":"higher","no":"lower"},"spread":{"spreading":"higher"},"readings":{"res_temp_high":"higher","do_low":"higher"}},"rule_out_first":["cause-pump-failure","cause-hot-reservoir","cause-low-dissolved-oxygen","cause-root-staining"],"distinguishing_questions":["q-root-colour","q-root-smell","q-res-temp","q-system","q-spread"],"tests":["test-root-inspection","test-root-smell","test-reservoir-temp","test-dissolved-oxygen","test-lab-pathogen"],"fix":"Act now. Fix conditions first: solution at 18-21 °C (65-70 °F), strong aeration (6-8+ mg/L DO), no overwatering. Change the reservoir, trim dead roots with clean scissors, clean and disinfect the system. Then either re-establish beneficial microbes (Bacillus, Trichoderma; house-preferred) or commit fully to a sterile regime (e.g. dosed hypochlorous acid or peroxide). Isolate affected plants on recirculating systems.","confirm":"New white root tips within 3-7 days and wilting stops; brown roots don't recover.","urgency":"critical","house_position":false,"article":"kb-diseases-root-rot-pythium","sources":["Punja ZK, Rodriguez G. 2018. Fusarium and Pythium species infecting roots of hydroponically grown marijuana (Cannabis sativa L.) plants. Canadian Journal of Plant Pathology 40(4):498-513. https://doi.org/10.1080/07060661.2018.1535466","University of Kentucky Cooperative Extension. Pythium root rot in hydroponic production (E-706). https://greenhousehort.ca.uky.edu/sites/greenhousehort.ca.uky.edu/files/E706.pdf","Colorado State University Extension PlantTalk 2043. Root disease problems and management in hydroponic systems. https://planttalk.colostate.edu/topics/miscellaneous/2043-root-disease-problems-management-hydroponic-systems/"]},{"id":"cause-fusarium","label":"Fusarium wilt or crown rot","kind":"disease","base_rate":"uncommon","symptoms":{"sym-pink-bud-rot":"hallmark","sym-branch-wilt":"hallmark","sym-stem-internal-browning":"hallmark","sym-stem-base-rot":"hallmark","sym-wilt-moist-not-recovering":"typical","sym-yellow-lower-leaves":"typical","sym-damage-one-side":"possible"},"contexts":{"spread":{"one_plant":"higher","some_plants":"higher"},"medium":{"soil":"higher","coco":"higher","living_soil":"higher"},"readings":{"temp_high":"higher"}},"rule_out_first":["cause-physical-damage","cause-underwatering","cause-root-rot-pythium"],"distinguishing_questions":["q-spread","q-root-colour","q-where-first"],"tests":["test-stem-cut","test-lab-pathogen","test-root-inspection"],"fix":"No cure once infected: remove the plant with its medium in a bag, sanitise pots, trays and water lines, and use clean clones and new media. Reduce root stress (overwatering, heat, salts) on the rest.","confirm":"No further wilting plants over the next 2-3 weeks.","urgency":"high","house_position":false,"article":"kb-diseases-fusarium","sources":["Punja ZK, Rodriguez G. 2018. Fusarium and Pythium species infecting roots of hydroponically grown marijuana (Cannabis sativa L.) plants. Canadian Journal of Plant Pathology 40(4):498-513. https://doi.org/10.1080/07060661.2018.1535466","Utah State University Extension. Hemp Fusarium wilt (IPM Notes). https://extension.usu.edu/planthealth/ipm/notes_ag/hemp-fusarium-wilt"]},{"id":"cause-hlvd","label":"Hop latent viroid (dudding)","kind":"disease","base_rate":"common","symptoms":{"sym-one-plant-stunted":"hallmark","sym-stunted":"typical","sym-brittle-stems":"typical","sym-compact-small-leaves":"typical","sym-airy-buds":"typical","sym-mosaic-mottle":"rare"},"contexts":{"spread":{"one_plant":"higher","some_plants":"higher","all_plants":"lower"},"recent_changes":{"new_plants":"higher"},"stage":{"late_flower":"higher","early_flower":"higher"}},"rule_out_first":["cause-root-bound","cause-root-aphids","cause-overwatering","cause-genetic-runt"],"distinguishing_questions":["q-spread","q-recent-changes"],"tests":["test-hlvd-pcr","test-sibling-compare"],"fix":"No cure in a plant. Test mothers (roots and leaves) by RT-PCR or RT-qPCR, discard positives, disinfect tools with 10% bleach or heat (alcohol and peroxide don't inactivate it), and use meristem tissue culture to rescue valuable genetics. Don't take cuttings from stunted plants.","confirm":"Negative tests on new mothers; no more duds in the next cycle.","urgency":"high","house_position":false,"article":"kb-diseases-hop-latent-viroid-and-viruses","sources":["Adkar-Purushothama CR, Sano T, Perreault JP. 2023. Hop latent viroid: a hidden threat to the cannabis industry. Viruses 15(3):681. https://doi.org/10.3390/v15030681","Oregon State University Extension. Hop latent viroid in hemp (EM 9570). https://extension.oregonstate.edu/catalog/em-9570-hop-latent-viroid-hemp"]},{"id":"cause-plant-virus","label":"Plant virus (e.g. beet curly top, lettuce chlorosis virus)","kind":"disease","base_rate":"rare","symptoms":{"sym-mosaic-mottle":"hallmark","sym-twisted-new-growth":"typical","sym-one-plant-stunted":"typical","sym-yellow-new-growth":"possible"},"contexts":{"light_type":{"sun":"higher"},"spread":{"one_plant":"higher","some_plants":"higher"}},"rule_out_first":["cause-broad-mites","cause-herbicide-injury","cause-hlvd"],"distinguishing_questions":["q-magnifier-underside","q-spread","q-light-type"],"tests":["test-lab-pathogen","test-magnifier"],"fix":"No cure: remove the plant. Control insect vectors (leafhoppers outdoors for curly top; whiteflies for some others) and test clone sources.","confirm":"No new symptomatic plants over the next 2-4 weeks.","urgency":"medium","house_position":false,"article":"kb-diseases-hop-latent-viroid-and-viruses","sources":["PNW Plant Disease Management Handbook. Hemp (Cannabis sativa) - Curly Top. https://pnwhandbooks.org/plantdisease/host-disease/hemp-cannabis-sativa-curly-top","Punja ZK. 2021. Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science 77:3857-3870. https://pmc.ncbi.nlm.nih.gov/articles/PMC8451794/"]},{"id":"cause-septoria","label":"Septoria leaf spot","kind":"disease","base_rate":"uncommon","symptoms":{"sym-spots-yellow-halo":"hallmark","sym-lower-leaves-dying-fast":"typical","sym-yellow-lower-leaves":"possible"},"contexts":{"light_type":{"sun":"higher"},"rh":{"high":"higher","very_high":"higher"},"where_first":{"old_growth":"higher"}},"rule_out_first":["cause-p-deficiency","cause-ca-deficiency","cause-spray-burn"],"distinguishing_questions":["q-where-first","q-light-type","q-rh"],"tests":["test-lab-pathogen","test-magnifier"],"fix":"Mainly outdoor and greenhouse. Strip infected lower leaves into a bag, keep foliage dry (water at the base), mulch to stop splash, open the lower canopy, clear debris; protectants only where registered.","confirm":"Spots stop climbing within 1-2 weeks.","urgency":"medium","house_position":false,"article":"kb-diseases-septoria-leaf-spot","sources":["University of Kentucky Plant Pathology. Septoria leaf spot of hemp (PPFS-AG-H-01). https://plantpathology.mgcafe.uky.edu/files/ppfs-ag-h-01.pdf","Punja ZK, et al. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://doi.org/10.3389/fpls.2019.01120"]},{"id":"cause-damping-off","label":"Damping-off","kind":"disease","base_rate":"common","symptoms":{"sym-damping-off":"hallmark","sym-seedling-stalled":"possible"},"contexts":{"stage":{"seedling":"higher","clone":"higher","veg":"lower","early_flower":"lower","late_flower":"lower"},"watering_frequency":{"before_dry":"higher"},"readings":{"temp_low":"higher","vpd_low":"higher"}},"rule_out_first":["cause-underwatering","cause-fungus-gnats"],"distinguishing_questions":["q-stage","q-watering-frequency"],"tests":["test-lift-pot"],"fix":"A collapsed seedling can't be saved. For the rest: clean containers, fresh mix, warm medium (22-26 °C / 72-79 °F), water lightly, good light and airflow.","confirm":"No further collapses.","urgency":"high","house_position":false,"article":"kb-germination-damping-off","sources":["University of Minnesota Extension. How to prevent seedling damping off. https://extension.umn.edu/solve-problem/how-prevent-seedling-damping","NC State Extension. Damping-off in flower and vegetable seedlings. https://content.ces.ncsu.edu/damping-off-in-flower-and-vegetable-seedlings"]},{"id":"cause-downy-mildew","label":"Downy mildew","kind":"disease","base_rate":"rare","symptoms":{"sym-fuzzy-underside-yellow-top":"hallmark"},"contexts":{"rh":{"very_high":"higher"},"readings":{"rh_high":"higher","temp_low":"higher"}},"rule_out_first":["cause-powdery-mildew","cause-mg-deficiency"],"distinguishing_questions":["q-rh","q-wipe-test"],"tests":["test-lab-pathogen"],"fix":"Rarely reported on cannabis. Remove infected leaves, drop RH and avoid cool wet nights; confirm with a lab before treating.","confirm":"No new patches within 2 weeks.","urgency":"medium","house_position":false,"article":"kb-diagnosis-white-grey-coatings-decision-tree","sources":["Punja ZK, et al. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://doi.org/10.3389/fpls.2019.01120"]},{"id":"cause-herm-genetic","label":"Hermaphrodite (herm-prone genetics revealed by stress)","kind":"genetic","base_rate":"common","symptoms":{"sym-nanners":"hallmark","sym-pollen-sacs":"hallmark","sym-seeds-in-buds":"typical"},"contexts":{"stage":{"early_flower":"higher","late_flower":"higher","veg":"lower"},"light_schedule":{"leak_or_interrupt":"higher"},"recent_changes":{"heat_event":"higher"}},"rule_out_first":["cause-light-leak"],"distinguishing_questions":["q-stage","q-light-schedule","q-recent-changes"],"tests":["test-anther-inspection","test-light-leak-check"],"fix":"Fix light leaks and stress, but treat the plant as defective genetics: remove it if it sheds pollen, never keep it as a mother and never breed from it. Late-flower bananas are not normal. A few early anthers can be picked off to save the crop, then check twice a week.","confirm":"No new anthers on twice-weekly checks; unaffected plants stay seed-free.","urgency":"high","house_position":true,"article":"kb-diagnosis-hermaphrodites","sources":["Punja ZK, Holmes JE. 2020. Hermaphroditism in marijuana (Cannabis sativa L.) inflorescences: impact on floral morphology, seed formation, progeny sex ratios, and genetic variation. Frontiers in Plant Science 11:718. https://doi.org/10.3389/fpls.2020.00718","GenetixBay house position (founder): herms are mainly breeder error; stress reveals susceptible genetics rather than causing intersex in sound lines. See kb-breeding-breeders-vs-pollen-chuckers."]},{"id":"cause-genetic-foxtailing","label":"Cultivar foxtailing (genetic)","kind":"genetic","base_rate":"uncommon","symptoms":{"sym-foxtails":"hallmark"},"contexts":{"top_only":{"no":"higher","yes":"lower"},"stage":{"late_flower":"higher"}},"rule_out_first":["cause-foxtail-stress","cause-light-bleaching","cause-heat-stress"],"distinguishing_questions":["q-top-only","q-ppfd","q-leaf-temp"],"tests":["test-sibling-compare","test-ppfd-meter"],"fix":"Nothing to fix if it appears evenly through the canopy, including shaded buds, in a cultivar known for it. Record it on the cultivar's GB-ID journal.","confirm":"Same pattern in siblings or the same cut in other grows.","urgency":"low","house_position":false,"article":"kb-diagnosis-foxtails","sources":["Punja ZK, Holmes JE. 2020. Hermaphroditism in marijuana (Cannabis sativa L.) inflorescences: impact on floral morphology, seed formation, progeny sex ratios, and genetic variation. Frontiers in Plant Science 11:718. https://doi.org/10.3389/fpls.2020.00718"]},{"id":"cause-genetic-anthocyanin","label":"Genetic purple colour (anthocyanin)","kind":"genetic","base_rate":"very_common","symptoms":{"sym-purple-veins":"typical","sym-purple-stems":"hallmark","sym-purple-leaves":"typical","sym-purple-buds":"hallmark"},"contexts":{"cultivar_purple":{"known_purple":"higher","not_purple":"lower"},"readings":{"night_cold":"higher"}},"rule_out_first":["cause-p-deficiency","cause-cold-stress"],"distinguishing_questions":["q-cultivar-purple","q-night-temp"],"tests":["test-sibling-compare"],"fix":"Nothing to fix: purple stems, petioles and bracts are mostly genetic and harmless, brought out by cool nights 5-10 °C (9-18 °F) below day. Purple is bag appeal, not potency.","confirm":"Leaves stay healthy and green apart from the colour; no spotting.","urgency":"low","house_position":true,"article":"kb-diagnosis-purple-stems-leaves","sources":["Bassolino L, Fulvio F, Pastore C, et al. 2023. When Cannabis sativa L. turns purple: biosynthesis and accumulation of anthocyanins. Antioxidants 12(7):1393. https://doi.org/10.3390/antiox12071393","Kim SR, Basnet P, Kovaleski AP, Ellison SL. 2025. Anthocyanin accumulation, inflorescence dry weight and total cannabidiol content have different temperature optima in Cannabis sativa. Journal of Cannabis Research 7:51. https://doi.org/10.1186/s42238-025-00311-w"]},{"id":"cause-genetic-runt","label":"Weak or slow individual phenotype","kind":"genetic","base_rate":"common","symptoms":{"sym-one-plant-stunted":"typical","sym-stunted":"possible"},"contexts":{"spread":{"one_plant":"higher","all_plants":"lower"},"stage":{"seedling":"higher","veg":"higher"}},"rule_out_first":["cause-hlvd","cause-root-aphids","cause-root-bound","cause-overwatering"],"distinguishing_questions":["q-spread","q-stage","q-root-colour"],"tests":["test-sibling-compare","test-hlvd-pcr","test-root-inspection"],"fix":"Seed-grown siblings vary; a consistently slow plant with healthy roots and a negative HLVd test is a phenotype, not a fault. Don't select it as a keeper or mother.","confirm":"Healthy roots, negative HLVd test, otherwise normal colour.","urgency":"low","house_position":false,"article":"kb-diagnosis-slow-growth","sources":["GenetixBay breeding note: seed lots segregate for vigour; see kb-breeding-selection-pheno-hunting."]},{"id":"cause-genetic-late-flowering","label":"Long-flowering or light-sensitive cultivar","kind":"genetic","base_rate":"uncommon","symptoms":{"sym-flowering-delayed":"typical","sym-excess-flower-stretch":"hallmark"},"contexts":{"light_schedule":{"flower_12":"higher","leak_or_interrupt":"lower"},"plant_type":{"photoperiod":"higher","autoflower":"lower"}},"rule_out_first":["cause-light-leak"],"distinguishing_questions":["q-light-schedule","q-plant-type"],"tests":["test-light-leak-check","test-sibling-compare"],"fix":"After the flip there is a 10-14 day transition before flowering really starts (up to 3 weeks in slow cultivars). Count from the flip and add the transition; flip earlier or train flatter for big-stretch cultivars.","confirm":"Pistils at the top of the main stem by about 3 weeks after the flip.","urgency":"low","house_position":true,"article":"kb-environment-flip-to-flower-transition","sources":["Zhang M, Anderson SL, Brym ZT, Pearson BJ. 2021. Photoperiodic flowering response of essential oil, grain, and fiber hemp (Cannabis sativa L.) cultivars. Frontiers in Plant Science 12:694153. https://doi.org/10.3389/fpls.2021.694153","Spitzer-Rimon B, Duchin S, Bernstein N, Kamenetsky R. 2019. Architecture and florogenesis in female Cannabis sativa plants. Frontiers in Plant Science 10:350. https://doi.org/10.3389/fpls.2019.00350"]},{"id":"cause-normal-senescence","label":"Normal late-flower fade (senescence)","kind":"normal_senescence","base_rate":"very_common","symptoms":{"sym-late-flower-fade":"hallmark","sym-yellow-lower-leaves":"typical","sym-purple-leaves":"possible","sym-red-petioles-yellow-lower":"possible"},"contexts":{"stage":{"late_flower":"higher","veg":"lower","seedling":"lower","early_flower":"lower"},"speed":{"weeks":"higher","hours":"lower"}},"rule_out_first":["cause-n-deficiency","cause-root-rot-pythium"],"distinguishing_questions":["q-stage","q-speed","q-feed-strength"],"tests":["test-runoff-ec"],"fix":"Nothing to fix in the last 2-3 weeks of flower. Keep feeding at stage strength with N tapered; don't 'flush' (pre-harvest flushing starves the plant while it packs on final weight and resin, and controlled studies show no quality gain). Fade before week 5-6 of flower suggests N was cut too early.","confirm":"Buds keep swelling and ripening normally while fan leaves fade.","urgency":"low","house_position":true,"article":"kb-diagnosis-yellowing-lower-leaves","sources":["Llewellyn D, Golem S, Jones AMP, Zheng Y. 2023. Foliar symptomology, nutrient content, yield, and secondary metabolite variability of cannabis grown hydroponically with different single-element nutrient deficiencies. Plants 12(3):422. https://doi.org/10.3390/plants12030422","GenetixBay house position: pre-harvest flushing is a myth (see kb-harvest-cure-flush-debate for the controlled studies)."]},{"id":"cause-shade-senescence","label":"Shaded lower leaves dying back (normal)","kind":"normal_senescence","base_rate":"very_common","symptoms":{"sym-yellow-lower-leaves":"typical","sym-lower-leaves-dying-fast":"possible"},"contexts":{"where_first":{"old_growth":"higher"},"speed":{"weeks":"higher"},"readings":{"ppfd_low":"higher"}},"rule_out_first":["cause-n-deficiency","cause-overwatering"],"distinguishing_questions":["q-where-first","q-speed"],"tests":["test-ppfd-meter"],"fix":"A few yellowing leaves deep in a dense canopy are normal; the plant recycles them. Tuck and train to open the canopy rather than stripping (house: tuck, don't pluck).","confirm":"Only shaded leaves affected; upper canopy healthy.","urgency":"low","house_position":true,"article":"kb-diagnosis-yellowing-lower-leaves","sources":["Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020"]},{"id":"cause-normal-leaf-movement","label":"Normal leaf movement (praying by day, drooping at night)","kind":"normal_senescence","base_rate":"very_common","symptoms":{"sym-praying-leaves":"hallmark","sym-night-droop":"hallmark"},"contexts":{"pot_weight":{"light":"lower"}},"rule_out_first":["cause-underwatering"],"distinguishing_questions":["q-pot-weight"],"tests":["test-lift-pot"],"fix":"Nothing to fix. Healthy cannabis angles leaves toward strong light and relaxes them at night.","confirm":"Leaves follow the light cycle with no damage.","urgency":"low","house_position":false,"article":"kb-answers-praying-leaves","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-cotyledon-senescence","label":"Seed leaves yellowing as true leaves take over (normal)","kind":"normal_senescence","base_rate":"very_common","symptoms":{"sym-yellow-cotyledons":"hallmark"},"contexts":{"stage":{"seedling":"higher","veg":"higher"},"speed":{"weeks":"higher"}},"rule_out_first":["cause-overwatering","cause-overfeeding"],"distinguishing_questions":["q-stage","q-pot-weight"],"tests":["test-lift-pot"],"fix":"Normal after 2-4 weeks once several true-leaf sets are growing. Early yellowing with wet medium is overwatering; with hot soil it may be over-strong soil.","confirm":"True leaves keep growing green.","urgency":"low","house_position":false,"article":"kb-answers-seedling-leaves-yellow","sources":["Sorokin A, Yadav NS, Gaudet D, Kovalchuk I. 2021. Development and standardization of rapid and efficient seed germination protocol for Cannabis sativa. Bio-protocol 11(1):e3875. https://doi.org/10.21769/BioProtoc.3875"]},{"id":"cause-normal-flower-stretch","label":"Normal stretch after the flip","kind":"normal_senescence","base_rate":"very_common","symptoms":{"sym-stretchy":"typical","sym-excess-flower-stretch":"possible"},"contexts":{"stage":{"early_flower":"higher","veg":"lower"},"recent_changes":{"flip":"higher"}},"rule_out_first":["cause-low-light"],"distinguishing_questions":["q-stage","q-ppfd"],"tests":["test-ppfd-meter"],"fix":"Most cultivars grow 1.5-3x in the first 2-3 weeks after the flip. Plan height before the flip; supercrop or LST through it.","confirm":"Stretch stops by about weeks 3-4 of flower.","urgency":"low","house_position":false,"article":"kb-diagnosis-stretching","sources":["Spitzer-Rimon B, Duchin S, Bernstein N, Kamenetsky R. 2019. Architecture and florogenesis in female Cannabis sativa plants. Frontiers in Plant Science 10:350. https://doi.org/10.3389/fpls.2019.00350"]},{"id":"cause-normal-trichomes","label":"Trichomes or harmless features mistaken for a problem","kind":"normal_senescence","base_rate":"common","symptoms":{"sym-white-sparkle-trichomes":"hallmark"},"contexts":{"wipe_test":{"no_wipe":"higher","wipes_returns":"lower"},"stage":{"early_flower":"higher","late_flower":"higher"}},"rule_out_first":["cause-powdery-mildew"],"distinguishing_questions":["q-wipe-test"],"tests":["test-wipe","test-magnifier"],"fix":"Nothing to fix: under a lens, trichomes are stalked glands with round heads, not powder.","confirm":"They don't wipe off and increase with ripeness.","urgency":"low","house_position":false,"article":"kb-diagnosis-white-powder-on-leaves","sources":["Punja ZK, et al. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://doi.org/10.3389/fpls.2019.01120"]},{"id":"cause-transplant-shock","label":"Transplant shock","kind":"physical","base_rate":"common","symptoms":{"sym-droop-after-transplant":"hallmark","sym-stunted":"typical","sym-yellow-lower-leaves":"possible","sym-auto-small":"possible"},"contexts":{"recent_changes":{"transplant":"higher"},"plant_type":{"autoflower":"higher"},"speed":{"days":"higher"}},"rule_out_first":["cause-overwatering","cause-ph-low-lockout","cause-ph-high-lockout"],"distinguishing_questions":["q-recent-changes","q-plant-type","q-pot-weight"],"tests":["test-lift-pot","test-ph-input-runoff"],"fix":"Move the root ball intact into pre-moistened medium of the same type and pH, water in with a mild solution, lower light 10-20% and keep RH slightly higher for 2-3 days. Mild droop for 2-5 days is normal; longer means root damage, waterlogging or a pH mismatch. Autos: sow in the final pot instead.","confirm":"Turgor back in 1-3 days; new growth within a week.","urgency":"medium","house_position":true,"article":"kb-germination-transplanting","sources":["Poorter H, Buhler J, van Dusschoten D, Climent J, Postma JA. 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth. Functional Plant Biology 39(11):839-850. https://doi.org/10.1071/FP12049","GenetixBay house position (founder): autoflowers run on a strict countdown; transplanting is almost a no-no and topping never matches proper LST. See kb-basics-photoperiod-vs-autoflower."]},{"id":"cause-physical-damage","label":"Physical damage (kinks, splits, broken branches)","kind":"physical","base_rate":"common","symptoms":{"sym-stem-damage":"hallmark","sym-branch-wilt":"typical","sym-damage-one-side":"possible"},"contexts":{"recent_changes":{"trained":"higher"},"spread":{"one_plant":"higher"}},"rule_out_first":["cause-fusarium"],"distinguishing_questions":["q-recent-changes","q-spread"],"tests":["test-stem-cut"],"fix":"Splint and tape a split stem within hours (tape, plant tie or a straw splint); a supercropped knuckle heals stronger in 3-7 days. Remove fully broken branches with a clean cut. Support heavy colas with a trellis.","confirm":"Leaves above the wound regain turgor within 1-2 days; a callus forms within a week.","urgency":"medium","house_position":false,"article":"kb-training-hst-supercropping","sources":["GenetixBay house position (founder): stem snapping (supercropping) is house-endorsed grower practice. See kb-training-hst-supercropping."]},{"id":"cause-training-stress","label":"Recovery stall after topping, supercropping or heavy defoliation","kind":"physical","base_rate":"common","symptoms":{"sym-stunted":"typical","sym-droop-after-transplant":"rare","sym-auto-small":"possible"},"contexts":{"recent_changes":{"trained":"higher"},"plant_type":{"autoflower":"higher"}},"rule_out_first":["cause-overwatering","cause-transplant-shock"],"distinguishing_questions":["q-recent-changes","q-plant-type"],"tests":["test-response-to-fix"],"fix":"Give 3-7 days for photoperiods to recover from topping or HST before the next session; don't stack stresses. Prefer tucking to stripping leaves. On autos use LST only.","confirm":"New growth resumes within a week.","urgency":"low","house_position":true,"article":"kb-answers-recovery-after-topping","sources":["GenetixBay house position (founder): stem snapping (supercropping) is house-endorsed grower practice. See kb-training-hst-supercropping.","GenetixBay house position (founder): autoflowers run on a strict countdown; transplanting is almost a no-no and topping never matches proper LST. See kb-basics-photoperiod-vs-autoflower."]},{"id":"cause-spray-burn","label":"Spray or foliar burn (pesticide, oil, soap, foliar feed)","kind":"physical","base_rate":"common","symptoms":{"sym-random-dead-patches":"hallmark","sym-white-residue":"typical","sym-burnt-tips":"possible","sym-taco-leaves":"possible","sym-rust-spots-new":"possible"},"contexts":{"recent_changes":{"sprayed":"higher"},"speed":{"days":"higher","hours":"higher","weeks":"lower"},"readings":{"ppfd_high":"higher","temp_high":"higher"}},"rule_out_first":[],"distinguishing_questions":["q-recent-changes","q-speed","q-where-first"],"tests":["test-magnifier","test-wipe"],"fix":"Stop spraying; rinse residue off with plain water at lights-off if damage is fresh. In future spray only at lights-off or with lights raised, test one leaf 24-48 h first, never mix sulfur with oils, and never spray buds.","confirm":"No new damage on leaves that grow after the spray.","urgency":"low","house_position":false,"article":"kb-answers-what-can-i-spray-in-flower","sources":["UC IPM. Pesticides: safe and effective use in the home and landscape (oils, soaps; phytotoxicity). https://ipm.ucanr.edu/PMG/PESTNOTES/pn74126.html"]},{"id":"cause-spray-residue","label":"Hard-water or spray residue","kind":"physical","base_rate":"common","symptoms":{"sym-white-residue":"hallmark"},"contexts":{"wipe_test":{"wipes_stays_gone":"higher","wipes_returns":"lower"},"recent_changes":{"sprayed":"higher"},"water_source":{"well":"higher","tap_chlorine":"higher","tap_chloramine":"higher"}},"rule_out_first":["cause-powdery-mildew"],"distinguishing_questions":["q-wipe-test","q-recent-changes","q-water-source"],"tests":["test-wipe"],"fix":"Harmless in itself; stop misting with hard water (use RO for foliar sprays) and wipe off heavy residue that blocks light.","confirm":"Doesn't come back after wiping.","urgency":"low","house_position":false,"article":"kb-diagnosis-white-powder-on-leaves","sources":["NC State Extension. Producing conventional tobacco transplants in greenhouses: water quality. https://content.ces.ncsu.edu/producing-conventional-tobacco-transplants-in-greenhouses-water-quality"]},{"id":"cause-herbicide-injury","label":"Herbicide drift or residue","kind":"physical","base_rate":"rare","symptoms":{"sym-twisted-new-growth":"typical","sym-small-narrow-new-leaves":"typical","sym-mosaic-mottle":"possible","sym-damage-one-side":"possible"},"contexts":{"light_type":{"sun":"higher"},"recent_changes":{"new_plants":"lower"},"spread":{"all_plants":"higher"}},"rule_out_first":["cause-broad-mites","cause-plant-virus","cause-ca-deficiency"],"distinguishing_questions":["q-magnifier-underside","q-light-type","q-spread"],"tests":["test-magnifier","test-lab-pathogen"],"fix":"Outdoors or with contaminated compost, manure or straw (persistent herbicide residues). Remove the source, repot into clean media; new growth may normalise slowly. Cannabis-specific symptom descriptions are scarce.","confirm":"New growth normalises over 2-4 weeks after the source is removed.","urgency":"medium","house_position":false,"article":"kb-diagnosis-curling-clawing-decision-tree","sources":["Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9"]},{"id":"cause-seed-shell-stuck","label":"Seed coat stuck on the cotyledons (helmet head)","kind":"physical","base_rate":"common","symptoms":{"sym-seed-shell-stuck":"hallmark","sym-seedling-stalled":"possible"},"contexts":{"stage":{"seedling":"higher","veg":"lower","early_flower":"lower","late_flower":"lower"},"readings":{"rh_low":"higher"}},"rule_out_first":["cause-damping-off"],"distinguishing_questions":["q-stage","q-rh"],"tests":["test-hygrometer-check"],"fix":"Mist the shell to soften it and raise RH around the seedling (dome) for a few hours; if it is still stuck, ease it off gently with clean tweezers. Plant seeds about 0.5-1.5 cm (1/4-1/2 in) deep so the medium scrapes the coat off on the way up.","confirm":"Cotyledons open within a day.","urgency":"medium","house_position":false,"article":"kb-answers-seed-shell-stuck-on-seedling","sources":["Sorokin A, Yadav NS, Gaudet D, Kovalchuk I. 2021. Development and standardization of rapid and efficient seed germination protocol for Cannabis sativa. Bio-protocol 11(1):e3875. https://doi.org/10.21769/BioProtoc.3875"]},{"id":"cause-springtails","label":"Springtails (harmless soil insects)","kind":"pest","base_rate":"common","symptoms":{"sym-tiny-white-jumpers-soil":"hallmark"},"contexts":{"medium":{"living_soil":"higher","soil":"higher","water":"lower"},"watering_frequency":{"before_dry":"higher"}},"rule_out_first":["cause-root-aphids","cause-fungus-gnats"],"distinguishing_questions":["q-medium","q-flying-insects"],"tests":["test-root-ball-insects"],"fix":"Nothing to fix: springtails eat decaying organic matter and fungi. Let the surface dry more between waterings if numbers bother you. Check the roots to rule out root aphids, which are pear-shaped, slow and sit on the roots.","confirm":"Plant healthy; roots clean.","urgency":"low","house_position":false,"article":"kb-answers-small-white-bugs-in-soil","sources":["UC IPM. Pest Notes: Fungus Gnats (Publication 7448). https://ipm.ucanr.edu/legacy_assets/pdf/pestnotes/pnfungusgnats.pdf"]}],"questions":[{"id":"q-stage","text":"What stage is the plant in?","type":"single","options":[{"id":"seedling","label":"Seedling (first 2-3 weeks)"},{"id":"clone","label":"Clone or cutting, not yet rooted"},{"id":"veg","label":"Veg"},{"id":"early_flower","label":"Flower weeks 1-4 (counting from the flip)"},{"id":"late_flower","label":"Flower week 5 onward"}],"why":"Late-flower yellowing is often normal fade, seedlings are overwatered far more often than underfed, and bud rot and herms only matter in flower.","journal_field":"stage"},{"id":"q-plant-type","text":"Is it an autoflower or a photoperiod plant?","type":"single","options":[{"id":"photoperiod","label":"Photoperiod (flowers when the light is cut to about 12 hours)"},{"id":"autoflower","label":"Autoflower (flowers by age)"},{"id":"unknown","label":"Not sure"}],"why":"Autoflowers run on a countdown from germination, so any stress (transplanting, overwatering, topping) shows as stunting that never recovers.","journal_field":"plant_type"},{"id":"q-medium","text":"What is it growing in?","type":"single","options":[{"id":"soil","label":"Bagged potting soil or peat mix"},{"id":"living_soil","label":"Living or super soil (organic, amended)"},{"id":"coco","label":"Coco coir (with or without perlite)"},{"id":"rockwool","label":"Rockwool"},{"id":"clay_inert","label":"Clay pebbles or another inert aggregate"},{"id":"water","label":"Water only (DWC, RDWC, NFT, aeroponics, Kratky)"}],"why":"pH ranges differ (soil 6.0-7.0, soilless and hydro 5.5-6.5); coco grabs calcium and magnesium; organic soils release nutrients slowly; water culture lives or dies by oxygen and temperature.","journal_field":"medium"},{"id":"q-system","text":"How is it watered or fed?","type":"single","options":[{"id":"hand_water","label":"Hand watering"},{"id":"drip_dtw","label":"Drip, drain to waste"},{"id":"recirc","label":"Recirculating drip or ebb and flow"},{"id":"dwc","label":"DWC or RDWC (roots in aerated water)"},{"id":"nft","label":"NFT (film of water in a channel)"},{"id":"aero_lpa","label":"Low-pressure aeroponics or cloner"},{"id":"aero_hpa","label":"High-pressure aeroponics (misting nozzles)"},{"id":"kratky","label":"Kratky (passive, no pump)"},{"id":"wick","label":"Wick or bottom watering"}],"why":"Recirculating systems spread root disease to every plant; HPA and NFT roots die within minutes to hours when a pump fails; DWC depends on dissolved oxygen and water temperature.","journal_field":"system"},{"id":"q-where-first","text":"Where did the problem show first?","type":"single","options":[{"id":"old_growth","label":"Oldest, lowest leaves"},{"id":"new_growth","label":"Newest leaves and growing tips"},{"id":"top_near_light","label":"Top of the canopy, closest to the light"},{"id":"middle","label":"Middle of the plant"},{"id":"whole_plant","label":"Everywhere at once"},{"id":"random","label":"Random patches, one side or a single branch"}],"why":"The single most useful question: mobile nutrients (N, P, K, Mg) show on old growth; immobile ones (Ca, Fe, Mn, Zn, B, Cu, S) on new growth; light and heat show at the top; pests, sprays and physical damage are patchy.","journal_field":null},{"id":"q-speed","text":"How fast did it appear and spread?","type":"single","options":[{"id":"hours","label":"Within hours"},{"id":"days","label":"Over a few days"},{"id":"weeks","label":"Slowly, over weeks"}],"why":"Hours points to water, a pump or heat failure, or a spray; days to root disease, pests or a pH crash; weeks to nutrition and normal ageing.","journal_field":null},{"id":"q-spread","text":"How many plants are affected?","type":"single","options":[{"id":"one_plant","label":"One plant only"},{"id":"some_plants","label":"Some plants"},{"id":"all_plants","label":"All plants about equally"},{"id":"spreading","label":"It started on one and is moving to others"}],"why":"Every plant equally points to the shared feed, water, climate or light; one plant among identical siblings points to its roots, its genetics or a virus; spreading points to pests or disease.","journal_field":null},{"id":"q-ph-input","text":"What is the pH of the water or feed you give (after nutrients)?","type":"number","options":[],"why":"Input pH should sit in range for the medium: soil 6.0-7.0, coco/rockwool/peat 5.5-6.5, hydro 5.5-6.2. Use a calibrated meter; drops and strips are too coarse to diagnose with.","journal_field":"ph_in"},{"id":"q-ph-runoff","text":"What is the pH of the runoff, slurry or reservoir (what the roots actually sit in)?","type":"number","options":[],"why":"Root-zone pH, not input pH, decides availability. High (soil >7.0, soilless >6.5) locks out Fe, Mn, Zn, B and P; low (soil <6.0, soilless <5.5) starves Ca, Mg and Mo and floods the roots with Mn and Fe.","journal_field":"ph_out"},{"id":"q-ec-input","text":"What is the EC of the feed you give, in mS/cm (or ppm and which scale)?","type":"number","options":[],"why":"Typical input EC: seedlings and clones 0.4-1.0, veg 1.2-1.8, flower 1.6-2.2 mS/cm. Above about 2.4 mS/cm most cultivars show tip burn; below about 0.8 in veg most go hungry. ppm500 = EC x 500, ppm700 = EC x 700.","journal_field":"ec_in"},{"id":"q-ec-runoff","text":"What is the EC of the runoff or reservoir, in mS/cm?","type":"number","options":[],"why":"Runoff more than about 0.5 mS/cm above input means salts are building up; well below input means the plant is eating faster than you feed. In a reservoir, EC rising while the level falls means the plant is drinking more water than nutrients.","journal_field":"ec_out"},{"id":"q-water-source","text":"What water do you use?","type":"single","options":[{"id":"tap_chlorine","label":"Tap water (chlorinated)"},{"id":"tap_chloramine","label":"Tap water (chloraminated, or not sure)"},{"id":"ro","label":"RO or distilled"},{"id":"well","label":"Well or bore water"},{"id":"rain","label":"Rainwater"},{"id":"softened","label":"Water from a salt (ion-exchange) softener"}],"why":"RO water carries no Ca or Mg; hard and well water carry alkalinity that pushes pH up; softened water swaps calcium for sodium; chloramine does not gas off and can hurt living soil and microbes.","journal_field":"water_source"},{"id":"q-alkalinity","text":"What is your water's alkalinity (mg/L as CaCO3), from a water report or test kit?","type":"number","options":[],"why":"Alkalinity, not water pH, is what drags root-zone pH up over weeks. Above about 100-150 mg/L as CaCO3 (2-3 meq/L) part of it should be neutralised with acid.","journal_field":"water_alkalinity"},{"id":"q-air-temp","text":"What is the canopy air temperature with the lights on (°C or °F)?","type":"number","options":[],"why":"Day targets: veg 24-28 °C (75-82 °F), flower 22-26 °C (72-79 °F). Above about 30 °C (86 °F) photosynthesis falls unless light and CO2 are high.","journal_field":"temp_day"},{"id":"q-night-temp","text":"What is the temperature with the lights off?","type":"number","options":[],"why":"Nights 3-6 °C (5-10 °F) below day are normal. Below about 15 °C (59 °F) phosphorus and water uptake slow, purpling appears and growth stalls.","journal_field":"temp_night"},{"id":"q-rh","text":"What is the relative humidity in the canopy?","type":"single","options":[{"id":"very_low","label":"Under 35%"},{"id":"low","label":"35-45%"},{"id":"mid","label":"45-60%"},{"id":"high","label":"60-70%"},{"id":"very_high","label":"Over 70%"}],"why":"Low RH dries leaves and favours spider mites; high RH in flower favours bud rot and mildew and blocks calcium delivery to new growth.","journal_field":"rh"},{"id":"q-vpd","text":"What is the leaf VPD (kPa), if your controller or journal shows it?","type":"number","options":[],"why":"Common bands: seedlings and clones 0.4-0.8, veg 0.8-1.2, flower 1.0-1.5 kPa. Below about 0.5 kPa transpiration stalls (Ca delivery, mould); above about 1.7 kPa leaves taco and wilt.","journal_field":"vpd"},{"id":"q-res-temp","text":"Hydro only: what is the reservoir or root-zone water temperature?","type":"number","options":[],"why":"Keep nutrient solution at 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F) dissolved oxygen falls and Pythium thrives.","journal_field":"res_temp"},{"id":"q-do","text":"Hydro only: do you know the dissolved oxygen (mg/L)?","type":"number","options":[],"why":"Aim for 6-8 mg/L or more at the roots. Below about 5 mg/L roots suffocate, brown and invite Pythium.","journal_field":"dissolved_oxygen"},{"id":"q-ppfd","text":"What is the PPFD at the top of the canopy (µmol/m²/s), or the light distance and dimmer setting?","type":"number","options":[],"why":"Targets: seedlings and clones 100-300, veg 300-700 (up to ~900), flower 800-1,200 at ambient CO2. Top leaves bleaching or tacoing above about 1,100 without CO2 point to light; stretch below about 300 in veg points to too little.","journal_field":"ppfd"},{"id":"q-light-type","text":"What kind of light?","type":"single","options":[{"id":"led","label":"LED"},{"id":"hps_mh","label":"HPS, MH or CMH"},{"id":"fluorescent","label":"Fluorescent or household bulbs"},{"id":"sun","label":"Sun or greenhouse"}],"why":"HPS heats leaves more at the same PPFD, LED lets leaves run cooler than the air (Nelson and Bugbee 2015). LEDs do not create a Cal-Mag need; that is a myth.","journal_field":"light_type"},{"id":"q-light-schedule","text":"What is the light schedule, and has the dark period been interrupted?","type":"single","options":[{"id":"veg_long","label":"18/6 to 24/0 (veg)"},{"id":"flower_12","label":"12/12 or 13/11, uninterrupted dark"},{"id":"leak_or_interrupt","label":"Light leaks, timer faults or the tent opened with lights on in the dark period"},{"id":"irregular","label":"Changing or irregular schedule"}],"why":"Light in the dark period of flowering plants can delay flowering, trigger re-veg and reveal herm-prone genetics.","journal_field":"light_schedule"},{"id":"q-recent-changes","text":"What changed in the 1-2 weeks before it started?","type":"multi","options":[{"id":"transplant","label":"Transplanted or up-potted"},{"id":"new_feed","label":"New nutrient or recipe"},{"id":"feed_increase","label":"Raised feed strength"},{"id":"sprayed","label":"Sprayed anything (foliar, pesticide, oil, soap)"},{"id":"ph_change","label":"Big pH correction or new pH meter"},{"id":"light_change","label":"New light, light lowered or dimmer raised"},{"id":"flip","label":"Flipped to flower"},{"id":"heat_event","label":"Heat wave, AC or fan failure"},{"id":"cold_event","label":"Cold snap or heater failure"},{"id":"trained","label":"Topped, supercropped or heavily defoliated"},{"id":"new_plants","label":"Brought in new clones or plants"},{"id":"none","label":"Nothing changed"}],"why":"Most sudden problems follow a change. New clones bring mites, thrips, HLVd and mildew; sprays under strong light burn; transplants and heat cause wilting.","journal_field":"events"},{"id":"q-watering-frequency","text":"How often do you water, and how dry does the pot get between waterings?","type":"single","options":[{"id":"before_dry","label":"Before the pot gets lighter; the top is always wet"},{"id":"when_light","label":"When the pot is clearly lighter"},{"id":"bone_dry","label":"Only when the pot is bone dry or the plant droops"},{"id":"high_freq","label":"Several small irrigations a day (coco, rockwool, drip)"},{"id":"hydro_na","label":"Not applicable (water culture)"}],"why":"Overwatering (watering before the pot dries back) is the commonest beginner problem and mimics nitrogen deficiency and clawing; coco and rockwool like frequent small feeds instead.","journal_field":"watering"},{"id":"q-pot-weight","text":"Lift the pot: how heavy is it compared with right after watering?","type":"single","options":[{"id":"heavy","label":"Still heavy and wet"},{"id":"medium","label":"About half"},{"id":"light","label":"Light, almost dry"},{"id":"na","label":"Not applicable (hydro)"}],"why":"Drooping with a heavy pot is overwatering or roots that cannot drink; drooping with a light pot is thirst.","journal_field":null},{"id":"q-pot-size","text":"Pot size relative to the plant?","type":"single","options":[{"id":"too_small","label":"Small for the plant; roots out of the holes or circling"},{"id":"right","label":"About right"},{"id":"too_big","label":"Small plant in a big pot"}],"why":"Root-bound plants dry out fast and stall; small plants in big wet pots stay waterlogged.","journal_field":"pot_size"},{"id":"q-root-colour","text":"What do the roots look like?","type":"single","options":[{"id":"white","label":"White or cream with fuzzy fine tips"},{"id":"tan_firm","label":"Tan or tea-stained but firm"},{"id":"brown_slimy","label":"Brown, slimy; the outer skin slides off"},{"id":"few_roots","label":"Few roots, short brown stubby tips"},{"id":"circling","label":"Thick circling mat around the outside"},{"id":"not_checked","label":"Haven't looked"}],"why":"Healthy roots are white with fine tips. Slimy brown roots whose outer layer slides off leave a bare thread: Pythium root rot. Firm tan roots in a dark nutrient or tea-coloured solution are usually staining.","journal_field":"root_colour"},{"id":"q-root-smell","text":"Do the roots, reservoir or medium smell sour, rotten or like sewage?","type":"yes_no","options":[],"why":"Healthy roots smell earthy or of nothing. A rotten or sewer smell means anaerobic conditions and rot.","journal_field":null},{"id":"q-magnifier-underside","text":"With a 30-60x magnifier, what do you see on the undersides of affected leaves and on the newest growth?","type":"multi","options":[{"id":"nothing","label":"Nothing"},{"id":"moving_dots","label":"Tiny moving dots, eggs or shed skins"},{"id":"webbing","label":"Fine silk webbing"},{"id":"soft_insects","label":"Soft pear-shaped insects in clusters"},{"id":"slender_insects","label":"Slender, fast insects and black specks"},{"id":"white_flies","label":"Tiny white flies that lift off when disturbed"},{"id":"glassy_specks","label":"Barely visible glassy specks on new growth (only at 30x or more)"},{"id":"not_checked","label":"Haven't looked"}],"why":"Spider mites, thrips, aphids and whiteflies are visible at 10-20x; broad and russet mites need 30-60x. Many 'nutrient problems' on new growth are mites.","journal_field":null},{"id":"q-wipe-test","text":"Does the white coating wipe off with a damp finger, and does it come back in a few days?","type":"single","options":[{"id":"wipes_returns","label":"Wipes off as powder and comes back"},{"id":"wipes_stays_gone","label":"Wipes off and stays gone"},{"id":"no_wipe","label":"Doesn't wipe off; it is part of the leaf (spots, scars, sparkle)"},{"id":"na","label":"No white coating"}],"why":"Powdery mildew wipes off as a powder and returns; spray and hard-water residue wipes off and stays gone; trichomes and thrips scars don't wipe off.","journal_field":null},{"id":"q-sticky","text":"Are the leaves or the surfaces below the plant sticky or shiny?","type":"yes_no","options":[],"why":"Honeydew means sap feeders above: aphids, whiteflies, mealybugs or soft scale. Black sooty mould grows on it.","journal_field":null},{"id":"q-flying-insects","text":"Do you see small flying insects or catches on sticky cards?","type":"single","options":[{"id":"none","label":"None"},{"id":"small_black_flies","label":"Small black flies around the medium"},{"id":"white_flies","label":"Tiny white moth-like flies"},{"id":"slender_winged","label":"Slender winged insects on blue or yellow cards"},{"id":"moths","label":"Moths at night (outdoor or greenhouse)"}],"why":"Fungus gnats (black, around wet media), whiteflies (white, from leaf undersides), thrips (slender) and moths (caterpillars to come) each point to a different pest.","journal_field":null},{"id":"q-top-only","text":"Is the damage only on the top leaves or buds closest to the light, with lower and shaded leaves fine?","type":"yes_no","options":[],"why":"Damage only near the lamp points to light or heat. The same symptom in shaded leaves rules light out.","journal_field":null},{"id":"q-leaf-temp","text":"What is the leaf surface temperature at the canopy top (IR thermometer)?","type":"number","options":[],"why":"Leaf temperature, not air temperature, drives VPD and heat stress. Under LED leaves often run 1-3 °C below air; under HPS they can run above it.","journal_field":"leaf_temp"},{"id":"q-co2","text":"Do you add CO2, and what is the lights-on reading (ppm)?","type":"number","options":[],"why":"Ambient is about 420 ppm; 800-1,200 ppm helps only at high light. A sealed room without exchange can drop below 300 ppm and stall growth; very high levels waste money and can be unsafe for people (5,000 ppm workplace limit).","journal_field":"co2"},{"id":"q-feed-strength","text":"How strong is your feeding compared with the label or chart?","type":"single","options":[{"id":"none","label":"Plain water only"},{"id":"light","label":"Under half strength"},{"id":"full","label":"About label strength"},{"id":"heavy","label":"Above label strength or extra boosters"},{"id":"organic_amended","label":"Amended organic soil, top-dressing only"}],"why":"Overfeeding gives burnt tips and dark clawed leaves; plain water for weeks (a 'flush') starves the plant. Pre-harvest flushing is a myth that costs yield.","journal_field":"feed_strength"},{"id":"q-calmag","text":"Do you add a calcium-magnesium supplement?","type":"yes_no","options":[],"why":"Needed with RO water and unbuffered coco; often unnecessary on hard tap water with a complete feed, where extra calcium can suppress magnesium and potassium. LEDs do not create a Cal-Mag need.","journal_field":null},{"id":"q-cultivar-purple","text":"Does this cultivar (or its siblings and parents) normally turn purple, or is only this plant coloured?","type":"single","options":[{"id":"known_purple","label":"Known to purple"},{"id":"not_purple","label":"Not known to purple"},{"id":"unknown","label":"Don't know"}],"why":"Purple stems, petioles and bracts are mostly genetic anthocyanin, brought out by cool nights; they are a problem only alongside other symptoms.","journal_field":"cultivar"}],"tests":[{"id":"test-runoff-ec","label":"Measure runoff EC against input EC","how":"Water to 10-20% runoff, collect the runoff in a clean cup and measure EC of both with a calibrated meter (1.413 mS/cm standard). Runoff more than ~0.5 mS/cm above input means salt build-up; well below input means the plant is hungry or you are over-leaching. In hydro, compare reservoir EC with the EC you mixed.","interprets":{"runoff_ec_high":["cause-salt-buildup","cause-overfeeding","cause-n-toxicity","cause-sodium-toxicity"],"runoff_ec_low":["cause-n-deficiency","cause-underfeeding","cause-k-deficiency","cause-p-deficiency"],"ec_in_range":["cause-overwatering","cause-root-rot-pythium","cause-ph-high-lockout","cause-ph-low-lockout"]},"article":"kb-ph-ec-runoff-testing"},{"id":"test-ph-input-runoff","label":"Measure input pH and root-zone (runoff or reservoir) pH","how":"Calibrate the meter with fresh pH 7 and pH 4 buffers, then measure the mixed feed and the runoff (containers) or reservoir (hydro). Soil and living soil should sit at 6.0-7.0, coco, rockwool and peat mixes at 5.5-6.5, hydro at 5.5-6.2. Track 3+ readings; one reading is not a trend.","interprets":{"ph_high":["cause-ph-high-lockout","cause-high-alkalinity-water","cause-fe-deficiency","cause-mn-deficiency","cause-zn-deficiency"],"ph_low":["cause-ph-low-lockout","cause-mn-toxicity","cause-fe-toxicity","cause-mg-deficiency","cause-ca-deficiency"],"ph_in_range":["cause-n-deficiency","cause-overwatering","cause-light-bleaching","cause-heat-stress"]},"article":"kb-ph-ec-ph-nutrient-availability"},{"id":"test-pour-through","label":"Pour-through extraction for container pH and EC","how":"Water normally, wait 30 minutes to 2 hours, pour enough pH-adjusted water on top to collect about 50 mL of leachate (roughly 75 mL for a 15 cm pot, 150 mL for a 4 L pot, 350 mL for 11 L), and measure pH and EC of that 50 mL. Less disruptive than full runoff and more repeatable.","interprets":{"runoff_ec_high":["cause-salt-buildup","cause-overfeeding"],"runoff_ec_low":["cause-underfeeding","cause-n-deficiency"],"ph_high":["cause-ph-high-lockout","cause-high-alkalinity-water"],"ph_low":["cause-ph-low-lockout"]},"article":"kb-ph-ec-runoff-testing"},{"id":"test-slurry","label":"Slurry (1:2) test of the medium","how":"Take a sample from the root zone (not the top 2 cm), mix 1 part medium with 2 parts distilled water by volume, stir, wait 30 minutes and measure pH and EC of the liquid. Use it for soil and living soil where runoff is unreliable. Slurry EC reads lower than pour-through EC; compare like with like.","interprets":{"ph_high":["cause-ph-high-lockout","cause-high-alkalinity-water"],"ph_low":["cause-ph-low-lockout"],"runoff_ec_high":["cause-salt-buildup"],"runoff_ec_low":["cause-underfeeding","cause-n-deficiency"]},"article":"kb-ph-ec-runoff-testing"},{"id":"test-root-inspection","label":"Look at the roots","how":"Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.","interprets":{"roots_white":["cause-light-stress-photoinhibition","cause-heat-stress","cause-mg-deficiency","cause-n-deficiency","cause-spider-mites","cause-broad-mites"],"roots_brown_slimy":["cause-root-rot-pythium","cause-low-dissolved-oxygen","cause-hot-reservoir","cause-overwatering"],"roots_tan_firm":["cause-root-staining"],"roots_circling":["cause-root-bound"],"roots_stubby_tips":["cause-salt-buildup","cause-cu-toxicity","cause-b-deficiency","cause-overfeeding"],"insects_on_roots":["cause-root-aphids","cause-fungus-gnats"],"crown_lesion":["cause-fusarium"]},"article":"kb-diagnosis-root-problems-decision-tree"},{"id":"test-root-smell","label":"Smell test of roots, medium and reservoir","how":"Smell the roots, the bottom of the root ball, the drain water or the reservoir up close. Healthy roots smell earthy or of nothing. A sour, rotten, swampy or sewage smell means anaerobic conditions and rot. In hydro, a slimy feel on the reservoir walls or tubing adds to the case.","interprets":{"smell_rotten":["cause-root-rot-pythium","cause-low-dissolved-oxygen","cause-overwatering","cause-hot-reservoir"],"smell_normal":["cause-salt-buildup","cause-ph-high-lockout","cause-ph-low-lockout","cause-n-deficiency"]},"article":"kb-diseases-root-rot-pythium"},{"id":"test-lift-pot","label":"Lift the pot and check moisture at depth","how":"Lift the pot right after a full watering to learn its wet weight, then lift before each watering. Water when it is clearly lighter (about half the added water gone). Push a finger or a moisture probe 5 cm (2 in) down. Heavy for 3-4+ days with droop: overwatering. Very light with limp papery leaves: thirst.","interprets":{"pot_heavy":["cause-overwatering","cause-root-rot-pythium","cause-cold-root-zone"],"pot_light":["cause-underwatering","cause-root-bound","cause-hydrophobic-medium"]},"article":"kb-diagnosis-drooping-overwatering-vs-underwatering"},{"id":"test-magnifier","label":"Magnifier check of leaf undersides and new growth","how":"Use a 10-20x loupe for spider mites, thrips, aphids and whiteflies, and a 30-60x lens or clip-on phone macro for broad and russet mites. Check the undersides of 10 affected leaves across several plants and the newest shoot tips, in white light. Look for moving dots, eggs, shed skins, webbing, slender insects with black specks, and glassy specks on new growth.","interprets":{"moving_dots_or_eggs":["cause-spider-mites"],"webbing":["cause-spider-mites"],"slender_insects_black_specks":["cause-thrips"],"soft_insect_clusters":["cause-aphids"],"white_flies":["cause-whiteflies"],"glassy_specks_new_growth":["cause-broad-mites","cause-russet-mites"],"nothing_found":["cause-ca-deficiency","cause-heat-stress","cause-light-stress-photoinhibition","cause-b-deficiency","cause-spray-burn"]},"article":"kb-pests-spider-mites"},{"id":"test-white-paper-tap","label":"Tap a branch over white paper","how":"Hold white paper under a branch or bud and tap it sharply 3-4 times. Watch the paper for 30 seconds: moving specks are mites or thrips (smear them; spider mites leave red-brown or green streaks), larger fliers are whiteflies. A quick whole-room screen before the magnifier.","interprets":{"moving_specks":["cause-spider-mites","cause-thrips"],"slender_insects":["cause-thrips"],"flies_rise":["cause-whiteflies"],"nothing":["cause-ca-deficiency","cause-heat-stress"]},"article":"kb-pests-thrips"},{"id":"test-wipe","label":"Wipe test for white coatings","how":"Wipe a white spot gently with a damp finger or cotton bud and mark the leaf. Powdery mildew comes off as powder and reappears in 2-5 days on the same and nearby leaves; spray or hard-water residue wipes off and stays gone; trichomes and thrips scars do not wipe off. Wash hands afterwards: spores travel on fingers.","interprets":{"wipes_returns":["cause-powdery-mildew"],"wipes_stays_gone":["cause-spray-residue"],"does_not_wipe":["cause-thrips","cause-spider-mites","cause-normal-trichomes"]},"article":"kb-diagnosis-white-powder-on-leaves"},{"id":"test-sticky-cards","label":"Sticky cards for 1-2 weeks","how":"Hang yellow cards at canopy height and lay one flat on the medium surface; add blue cards for thrips. Count catches every 3-4 days. Rising counts of small dark flies at the medium mean fungus gnats; slender insects mean thrips; white wedge-shaped fliers mean whiteflies; winged aphids mean a colony nearby.","interprets":{"small_dark_flies":["cause-fungus-gnats"],"slender_insects":["cause-thrips"],"white_flies":["cause-whiteflies"],"winged_aphids":["cause-aphids","cause-root-aphids"]},"article":"kb-answers-do-sticky-traps-work"},{"id":"test-potato-slice","label":"Potato slice test for larvae in the medium","how":"Press 2-3 raw potato slices (1 cm thick) cut side down onto the medium surface. Lift after 2-4 days and look underneath: translucent larvae with shiny black heads are fungus gnat larvae.","interprets":{"larvae_found":["cause-fungus-gnats"],"none_found":["cause-root-aphids","cause-overwatering"]},"article":"kb-pests-fungus-gnats"},{"id":"test-root-ball-insects","label":"Root-ball and drainage-hole insect check","how":"Tip the plant out and inspect the outer roots, pot bottom and drainage holes with a 10x loupe. Root aphids are small, pear-shaped and wingless, often with white waxy flecks; check several plants, and the drain trays, since colonies hide at the pot edge.","interprets":{"aphids_on_roots":["cause-root-aphids"],"larvae_found":["cause-fungus-gnats"],"nothing_found":["cause-overwatering","cause-root-bound"]},"article":"kb-pests-root-aphids"},{"id":"test-leaf-temperature","label":"IR leaf temperature at the canopy top","how":"Point an IR thermometer at the top leaves under the light (5-10 cm away, emissivity 0.95) and at shaded leaves. Leaf temperature above about 30 °C (86 °F) at the top only points to heat or radiant load; leaf VPD can be calculated from leaf temperature and RH.","interprets":{"leaf_temp_high_top":["cause-heat-stress","cause-light-stress-photoinhibition"],"leaf_temp_normal":["cause-light-bleaching","cause-ca-deficiency","cause-broad-mites"]},"article":"kb-environment-heat-light-stress"},{"id":"test-ppfd-meter","label":"Measure PPFD at the canopy top","how":"Use a quantum (PAR) meter, or a calibrated phone app as a rough guide, at the top leaves in a 5-9 point grid. Compare with the stage target: seedlings 100-300, veg 300-700, flower 800-1,200 µmol/m²/s at ambient CO2. Bleaching and taco at the top above ~1,100 point to light; stretch below ~300 in veg points to too little.","interprets":{"ppfd_high":["cause-light-bleaching","cause-light-stress-photoinhibition","cause-foxtail-stress"],"ppfd_low":["cause-low-light"],"ppfd_in_range":["cause-heat-stress","cause-mg-deficiency","cause-s-deficiency","cause-fe-deficiency"]},"article":"kb-answers-measure-ppfd-without-a-par-meter"},{"id":"test-hygrometer-check","label":"Check temperature and RH at canopy height with a calibrated sensor","how":"Put a calibrated sensor (salt test: a sealed bag with damp table salt reads 75% RH after 8-12 hours) at canopy height, out of direct light, and log for 24 hours including lights-off. Look for lights-off RH spikes and dew point.","interprets":{"rh_high":["cause-low-vpd-high-rh","cause-botrytis","cause-powdery-mildew","cause-ca-deficiency"],"rh_low":["cause-high-vpd-low-rh","cause-spider-mites"],"temp_high":["cause-heat-stress"],"temp_low":["cause-cold-stress"]},"article":"kb-answers-calibrate-a-hygrometer"},{"id":"test-reservoir-temp","label":"Measure reservoir and root-zone temperature at the end of the light period","how":"Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.","interprets":{"res_temp_high":["cause-hot-reservoir","cause-root-rot-pythium","cause-low-dissolved-oxygen"],"res_temp_low":["cause-cold-root-zone"]},"article":"kb-diagnosis-root-browning-hydro"},{"id":"test-dissolved-oxygen","label":"Dissolved oxygen check","how":"Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.","interprets":{"do_low":["cause-low-dissolved-oxygen","cause-hot-reservoir"],"do_ok":["cause-root-rot-pythium","cause-root-staining"]},"article":"kb-systems-dwc"},{"id":"test-pump-check","label":"Check pumps, timers, nozzles and drippers","how":"Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.","interprets":{"pump_failed":["cause-pump-failure"],"pump_ok":["cause-root-rot-pythium","cause-heat-stress"]},"article":"kb-systems-hpa-aeroponics"},{"id":"test-water-report","label":"Get a water report (or test your water)","how":"Ask your water utility for the annual report or test well water: alkalinity (mg/L CaCO3), pH, EC, Ca, Mg, Na, Cl, B, and whether it uses chlorine or chloramine. Alkalinity above ~100-150 mg/L as CaCO3 pushes root-zone pH up; sodium above ~50 mg/L and chloride above ~70 mg/L are a problem; softened water is high in sodium.","interprets":{"alkalinity_high":["cause-high-alkalinity-water","cause-ph-high-lockout"],"sodium_high":["cause-sodium-toxicity","cause-chloride-toxicity"],"chloramine":["cause-chloramine"],"soft_ro_water":["cause-ca-deficiency","cause-mg-deficiency"],"boron_high":["cause-b-toxicity"]},"article":"kb-ph-ec-water-quality"},{"id":"test-leaf-tissue","label":"Leaf tissue analysis","how":"Send 20-30 most-recently-matured leaves (no petioles) from affected plants, and separately from healthy ones, to an agricultural lab. Compare with cannabis and hemp sufficiency ranges (for example N 3.3-4.8%, Mg 0.40-0.81%, K 1.8-2.9% dry weight in recent mature leaves). Results take 1-2 weeks; use it to confirm a chronic problem, not an emergency.","interprets":{"n_low":["cause-n-deficiency"],"p_low":["cause-p-deficiency"],"k_low":["cause-k-deficiency"],"ca_low":["cause-ca-deficiency"],"mg_low":["cause-mg-deficiency"],"s_low":["cause-s-deficiency"],"fe_low":["cause-fe-deficiency"],"mn_low":["cause-mn-deficiency"],"mn_high":["cause-mn-toxicity"],"zn_low":["cause-zn-deficiency"],"b_low":["cause-b-deficiency"],"b_high":["cause-b-toxicity"],"cu_low":["cause-cu-deficiency"],"na_high":["cause-sodium-toxicity"]},"article":"kb-nutrients-mobile-vs-immobile-nutrients"},{"id":"test-meter-calibration","label":"Check the meters against fresh standards","how":"Put the pH probe in fresh pH 7.0 and 4.0 buffer and the EC probe in a 1.413 mS/cm standard. If pH reads more than 0.1-0.2 off, recalibrate; if it can't be calibrated or the slope is below ~90-95%, replace the probe. Many 'lockouts' are a drifting meter.","interprets":{"meter_off":["cause-meter-error"],"meter_ok":["cause-ph-high-lockout","cause-ph-low-lockout"]},"article":"kb-ph-ec-meter-calibration"},{"id":"test-response-to-fix","label":"Watch new growth for 5-10 days after one change","how":"Make one correction at a time, mark the top node with a twist tie and photograph the same leaves every 2-3 days. Damaged leaves never recover; judge only new growth and whether the symptom stops spreading. Mobile-nutrient symptoms stop climbing within 5-7 days; immobile ones show in new leaves within 7-10 days.","interprets":{"new_growth_clean":["cause-n-deficiency","cause-mg-deficiency","cause-fe-deficiency","cause-ca-deficiency","cause-ph-high-lockout","cause-ph-low-lockout"],"keeps_spreading":["cause-broad-mites","cause-spider-mites","cause-root-rot-pythium","cause-hlvd"]},"article":"kb-diagnosis-how-to-diagnose-any-problem"},{"id":"test-light-leak-check","label":"Check for light leaks in the dark period","how":"Sit inside the tent or room for 5 minutes after lights-off until your eyes adjust. Look for pinholes, zips, vents, indicator LEDs on equipment and light under doors. Also confirm the timer actually switches off and stays off.","interprets":{"leak_found":["cause-light-leak","cause-herm-genetic","cause-reveg"],"no_leak":["cause-herm-genetic","cause-genetic-late-flowering"]},"article":"kb-environment-photoperiod-light-leaks"},{"id":"test-bud-inspection","label":"Open the densest colas","how":"In flower, gently spread the largest, densest colas at the base and look for brown, mushy or grey tissue around the stem, a single wilted sugar leaf that pulls out easily, frass or caterpillars. Check 5-10 colas per plant each week from mid-flower, more when RH is high. Bag any rot before removing it.","interprets":{"rot_found":["cause-botrytis"],"frass_found":["cause-caterpillars"],"clean":["cause-normal-senescence","cause-foxtail-stress"]},"article":"kb-diseases-botrytis-bud-rot"},{"id":"test-stem-cut","label":"Cut a wilting stem lengthwise","how":"On a wilting or dying branch, scrape the lower stem and cut it lengthwise with a clean blade. Brown streaks in the water-conducting tissue point to vascular wilt (Fusarium). A dark, sunken crown points to crown rot. Disinfect the blade afterwards.","interprets":{"vascular_browning":["cause-fusarium"],"crown_rot":["cause-fusarium","cause-root-rot-pythium"],"clean_stem":["cause-physical-damage","cause-underwatering","cause-heat-stress"]},"article":"kb-diseases-fusarium"},{"id":"test-hlvd-pcr","label":"Lab test for hop latent viroid (RT-PCR or RT-qPCR)","how":"Send root and leaf samples (roots detect HLVd earlier in young plants) to a lab offering HLVd RT-PCR or RT-qPCR. Test mother plants and any stunted plant among healthy siblings. A positive plant cannot be cured; tissue culture of meristem tips can rescue genetics.","interprets":{"positive":["cause-hlvd"],"negative":["cause-root-bound","cause-genetic-runt","cause-root-aphids"]},"article":"kb-diseases-hop-latent-viroid-and-viruses"},{"id":"test-lab-pathogen","label":"Send a sample to a plant diagnostic lab","how":"For rots, wilts, leaf spots and viruses you can't separate by eye, send a fresh sample (whole plant with roots or a wilting branch with healthy and diseased tissue) in a sealed bag to a university or commercial plant diagnostic clinic. Results in days to 2 weeks.","interprets":{"fusarium":["cause-fusarium"],"pythium":["cause-root-rot-pythium"],"septoria":["cause-septoria"],"botrytis":["cause-botrytis"],"virus":["cause-plant-virus","cause-hlvd"]},"article":"kb-diseases-sanitation-and-prevention"},{"id":"test-anther-inspection","label":"Inspect buds and nodes for anthers and pollen sacs","how":"From week 2 of flower, check nodes and buds with a 10x loupe twice a week. Look for pollen sacs on stalks at nodes and pale-yellow banana-shaped anthers among the pistils. Mark and photograph what you find; check the whole plant, not one bud.","interprets":{"anthers_found":["cause-herm-genetic"],"none":["cause-foxtail-stress","cause-genetic-foxtailing"]},"article":"kb-guides-telling-sex-and-spotting-herms"},{"id":"test-sibling-compare","label":"Compare with siblings or the same cut","how":"Put the affected plant beside siblings or clones of the same cut in the same conditions. A trait shared by all of a cultivar (purple stems, foxtailing, pale colour) is genetic; a problem on one plant points to its roots, a virus or its genetics; a problem on every cultivar points to the environment or feed.","interprets":{"only_this_plant":["cause-hlvd","cause-genetic-runt","cause-root-aphids","cause-root-bound"],"whole_cultivar":["cause-genetic-anthocyanin","cause-genetic-foxtailing","cause-genetic-late-flowering"],"all_plants":["cause-heat-stress","cause-salt-buildup","cause-ph-high-lockout","cause-ph-low-lockout","cause-overwatering"]},"article":"kb-diagnosis-how-to-diagnose-any-problem"},{"id":"test-co2-check","label":"Measure CO2 during the light period","how":"Read a CO2 monitor at canopy height through the light period. A sealed room without enrichment can fall below 300-350 ppm and stall growth; enriched rooms should hold 800-1,200 ppm. Keep occupied spaces below the 5,000 ppm workplace limit.","interprets":{"co2_low":["cause-co2-depletion"],"co2_high":["cause-co2-excess"]},"article":"kb-environment-co2-enrichment"}]},"meta":{"articles":{"kb-answers-algae-in-reservoir":{"title":"How do I stop algae in my reservoir or on my medium?","url":"/knowledge/answers/algae-in-reservoir.html"},"kb-answers-calibrate-a-hygrometer":{"title":"How do I check if my hygrometer is accurate?","url":"/knowledge/answers/calibrate-a-hygrometer.html"},"kb-answers-do-sticky-traps-work":{"title":"Do sticky traps work?","url":"/knowledge/answers/do-sticky-traps-work.html"},"kb-answers-holes-in-leaves":{"title":"What is eating holes in my leaves?","url":"/knowledge/answers/holes-in-leaves.html"},"kb-answers-how-cold-is-too-cold":{"title":"How cold is too cold for cannabis?","url":"/knowledge/answers/how-cold-is-too-cold.html"},"kb-answers-how-often-to-water":{"title":"How often should I water my cannabis plants?","url":"/knowledge/answers/how-often-to-water.html"},"kb-answers-how-to-reveg-a-plant":{"title":"How do I reveg a plant after harvest?","url":"/knowledge/answers/how-to-reveg-a-plant.html"},"kb-answers-measure-ppfd-without-a-par-meter":{"title":"How can I measure PPFD without a PAR meter?","url":"/knowledge/answers/measure-ppfd-without-a-par-meter.html"},"kb-answers-pistils-turning-brown-early":{"title":"Why are my pistils turning brown early?","url":"/knowledge/answers/pistils-turning-brown-early.html"},"kb-answers-praying-leaves":{"title":"Are praying leaves a good sign?","url":"/knowledge/answers/praying-leaves.html"},"kb-answers-recovery-after-topping":{"title":"How long does a plant take to recover after topping?","url":"/knowledge/answers/recovery-after-topping.html"},"kb-answers-seed-shell-stuck-on-seedling":{"title":"What do I do if the seed shell is stuck on my seedling?","url":"/knowledge/answers/seed-shell-stuck-on-seedling.html"},"kb-answers-seedling-leaves-yellow":{"title":"Why are my seedling's leaves yellow or pale?","url":"/knowledge/answers/seedling-leaves-yellow.html"},"kb-answers-single-finger-leaves-reveg":{"title":"Why is my plant growing single-finger leaves?","url":"/knowledge/answers/single-finger-leaves-reveg.html"},"kb-answers-small-white-bugs-in-soil":{"title":"What are the small white bugs in my soil?","url":"/knowledge/answers/small-white-bugs-in-soil.html"},"kb-answers-water-runs-through-or-pools":{"title":"Why does water run straight through or pool on top of my pot?","url":"/knowledge/answers/water-runs-through-or-pools.html"},"kb-answers-weak-floppy-stems":{"title":"Why are my stems weak and floppy?","url":"/knowledge/answers/weak-floppy-stems.html"},"kb-answers-what-can-i-spray-in-flower":{"title":"What can I safely spray on plants in flower?","url":"/knowledge/answers/what-can-i-spray-in-flower.html"},"kb-answers-white-fuzz-on-soil":{"title":"What is the white fuzz on top of my soil?","url":"/knowledge/answers/white-fuzz-on-soil.html"},"kb-answers-whole-plant-pale-green":{"title":"Why is my whole plant pale or light green?","url":"/knowledge/answers/whole-plant-pale-green.html"},"kb-answers-why-are-my-buds-airy":{"title":"Why are my buds airy or larfy?","url":"/knowledge/answers/why-are-my-buds-airy.html"},"kb-answers-why-are-my-clones-wilting":{"title":"Why are my clones wilting?","url":"/knowledge/answers/why-are-my-clones-wilting.html"},"kb-answers-why-are-there-seeds-in-my-buds":{"title":"Why are there seeds in my buds?","url":"/knowledge/answers/why-are-there-seeds-in-my-buds.html"},"kb-answers-why-is-my-autoflower-small":{"title":"Why is my autoflower so small?","url":"/knowledge/answers/why-is-my-autoflower-small.html"},"kb-answers-why-is-my-seedling-drooping":{"title":"Why is my seedling drooping?","url":"/knowledge/answers/why-is-my-seedling-drooping.html"},"kb-diagnosis-brown-burnt-tips":{"title":"Brown or burnt leaf tips on cannabis: a differential","url":"/knowledge/diagnosis/brown-burnt-tips.html"},"kb-diagnosis-bud-problems-decision-tree":{"title":"Cannabis bud problems: the master decision tree","url":"/knowledge/diagnosis/bud-problems-decision-tree.html"},"kb-diagnosis-clawing-leaves":{"title":"Clawing leaves on cannabis: a differential","url":"/knowledge/diagnosis/clawing-leaves.html"},"kb-diagnosis-curling-clawing-decision-tree":{"title":"Why are my cannabis leaves curling? 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