sodium bicarbonate

[gorbelly]

Originally Posted by jmsieglaff

Whipped up a batch tonight and treated my cucubrits which were just starting to get powdery mildew. I was amazed that it seems to work instantly. The leaves that I treated first that had some signs no longer did. I was careful to get tops and bottoms of the leaves. I also treated some flox that always get PM. I'm curious to how things will look tomorrow and in the coming days. Thanks again Ray!

Plain water will wash off a lot of the powdery mildew spores that have not had time to "embed" into the foliage. Anything with a surfactant and/or sticker that leaves a residue will also diminish the appearance of any kind of powder on plant foliage.

I'm not saying that potassium bicarb isn't helping--it's shown to be effective--but just the physical action of washing the leaves with a liquid helps as well.