Plant problems · Diseases · Any stage · Act today
Powdery mildew
What you see
- White, flour like patches on the top of leaves
- Patches spread and join up
- In bad cases it reaches the buds
Why it happens
A fungus that loves stagnant air, big swings between day and night temperature and medium humidity.
What to do
- Remove infected leaves carefully into a bag
- In veg, spray a potassium bicarbonate or milk solution (1 part milk to 9 parts water) on the leaves
- Improve airflow and keep humidity steady
- Never spray buds in flower; infected buds should not be smoked
Next time
- Keep air moving
- Avoid big temperature swings
Easy to confuse with
- Air too humid: Water drops on leaves or walls in the morning
- Thrips: Silvery, shiny scratches on leaves
Not sure?
Take a photo of a leaf with the white patches, close up and ask the Grow Doctor, or send it to the grow companion on Telegram.