Irregular dead or bleached patches after spraying
Appears 1-3 days after a spray, on the leaves and leaf parts that were wet, worst where droplets pooled; does not spread afterwards..
- Also called
- spray burn
- leaves burnt after spraying
- foliar burn
- droplet burn spots
- neem burn
- white patches after spray
Likely causes, most likely first
Ranked for this sign on its own. Your stage, medium and readings change the order, so run the checker for your plant.
LikelySpray or foliar burn (pesticide, oil, soap, foliar feed)
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.
Recovery: No new damage on leaves that grow after the spray.
How to confirm it
- 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.
- Wipe test for white coatings. 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.
Look for
Dried-droplet shaped tan or white spots, drip-edge burns on leaf tips, damage limited to sprayed surfaces..
The full guide: Spots, brown patches and dead edges on cannabis leaves: the master decision tree
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.
