Is there a natural remedy for treating Powdery Mildew of Squash and Pumpkin?
I have a yearly problem of powdery mildew on squash and zucchini plants. Use a fungicide from local store but isn’t very effective. Is there a natural remedy that I could mix up to spray on leaves? Should I treat soil this fall with anti fungal?
Powdery Mildew of Squash and Pumpkin is a very common disease of all cucurbits. This fungal disease is caused by the release of airborne spores which can travel long distances to find susceptible hosts. That might explain why your use of fungicides has not been effective, as the disease pressures are high over a long stretch of the season and fungicides may be washed off the plant thereby and only supply limited protection. The fungi are not soil borne and so soil treatment is not an option. Fortunately plant breeders have been working on resistant varieties of cucurbits for quite some time and so choosing resistant varieties would be the first step in prevention for next year. Also the disease spreads under humid conditions so spacing your crops adequately to improve air flow around the crop would also help to avoid or slow down the spread.
For more information on the disease and cultural practices you can employ to reduce the occurrence please view this Fact Sheet on Cucurbit Powdery Mildew.
In addition, please also view this Cornell University Fact Sheet on Disease Resistant Cucurbit Varieties.