Powdery Mildew: Stopping White Fuzz Before It Spreads
By The Budometry TeamPublished Updated
Powdery mildew looks like flour dusted on a leaf and wipes off with a finger, which distinguishes it from trichomes or residue. It spreads by airborne spores and thrives in exactly the conditions a crowded tent creates.
Part of our pillar guide: Plant Training, Pests and Troubleshooting
Conditions
High humidity above 60%, poor air circulation, dense foliage, and swinging temperatures. Unlike most fungi it does not need standing water on the leaf.
Veg treatment
Remove badly affected leaves and bag them. Improve airflow and drop humidity. Potassium bicarbonate sprays are effective and widely used. Repeat weekly until clean.
Flower
Avoid spraying anything onto buds. Focus on humidity control, defoliating to open the canopy, and increasing airflow. Heavily infected flower should be discarded rather than dried.
Prevention
Keep flowering RH at 45-50%, defoliate for penetration, space plants so leaves are not pressed together, and quarantine any new clone for a week.
Frequently asked questions
- Is powdery mildew dangerous to consume?
- Do not dry, cure, or consume visibly infected flower. Discard it.
The full guide on this topic
Plant Training, Pests and Troubleshooting
Topping, LST and SCROG explained, plus how to identify and stop spider mites, fungus gnats and powdery mildew, and how to read leaf symptoms correctly.