>>1858822This is pretty common, and if it's a serious problem you could lose the plant. Every year my lilac bush gets the white powder and it's totally inconsequential. However, as you can see here, my squash just couldn't handle the heat and humidity this year and are finally biting it.
Mind you, this is how they were looking for weeks now while I pruned the worst of it. It happens. Likely you can get away with pruning the most effected leaves. A tip I got from someone too was that you should prune redundant leaves for air flow. If a leaf is below two leaves and not getting sun, take it off. A fungacide wouldn't hurt, I just do the soap baking soda and oil mixed into water routine, but that isn't always going to work.
