Powdery Mildew... Treatment Plan

With the moist, cool and somewhat humid spring (typical of the Northwest), our squash, peppers and tomatoes (all heat and sunshine lovers) developed powdery mildew. Yuk!

We let it go a little too long and some of the leaves were covered with it. Research time! First we asked our neighbor at Bountiful Herbs Garden, who said we might be able to prevent further developments of it by spraying with baking soda mixed with water and a little liquid soap. We then searched on line, where we found many useful articles, particularly this one by a California Master Gardner. We decided not to risk contamination of our soil with baking soda and to try, instead, a commercial sulfur treatment.

But first, Robin pruned away all the seriously infected leaves, leaving only those with slight-blight. Powdery mildew spreads by contact such as by touching infected leaves with your fingers and then touching non-infected leaves or by wind, and can also spread by getting into the dirt. Therefore, we disposed of the pruned leaved in a sealed plastic bag in our garbage (not good for the compost!).

We then sprayed the new growth and remaining slight-blight growth using this fungicide which is recommended by our local Master Gardner group as good for organic gardening. I think we've saved our plants! This is how they look now, after pruning and spraying.