# Small tan dead specks between veins on upper leaves: likely causes and fixes

> Small tan dead specks between veins on upper leaves on cannabis is most often Manganese deficiency. How to tell them apart, the fix for each and what recovery looks like.

Also called: tiny brown dots upper leaves, pinpoint necrosis, speckled top leaves.

Run the checker with this sign: https://genetixbay.com/knowledge/diagnose/?at=new&s=tan-specks-upper

## Likely causes, most likely first

### Manganese deficiency (Possible)

- Kind: Nutrient; urgency: Low urgency
- 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.
- Recovery: New upper leaves lose the netted pattern within 7-10 days.
- Confirm: Measure input pH and root-zone (runoff or reservoir) pH: 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.
- Confirm: Magnifier check of leaf undersides and new growth: 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.
- Confirm: Leaf tissue analysis: 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.
- Article: [Manganese (Mn) in cannabis: netted chlorosis, low-pH toxicity and the iron balance](https://genetixbay.com/knowledge/nutrients/manganese.md)

## 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.