Powdery mildew will grow on the leaf when the leaves are wet, this happens in the fall and can happen summer when nights are cool water condensates on the leaf surfacePotassium bicarbonate? Talk to me! Frost definitely helps turpine levels too.
Or in very humid conditions there will be a film
of moisture on the leaf surface which can allow for
The mildew spore to start growing.
When you spray a potassium bicarbonate mixture on the leaves it makes the pH incredibly high (alkaline) which the mildew has a very hard time growing in. As it prefers a low pH (acidic)
It doesn’t necessarily kill the mildew just gives it a hard time to grow. So multiple applications will be required, you may also want to rinse your buds off really well before harvesting.