Toward the end of summer, powdery mildew on squash and cucumbers is common in the Willamette Valley and other places with similar weather conditions. Luckily, by this time of year, the cucumbers and summer squash are mostly harvested, and the winter squash is about ready for harvest.

Intervention at this time is neither needed nor effective. You can remove all the vines and either compost or place in yard debris bins. Powdery mildew only survives on a living host and the fungus will be killed during the composting process.

To help manage powdery mildew for the next growing season, plant resistant varieties if available, rotate your crops each year and avoid planting too dense.

Watch for signs of mildew early in the growing season. If it appears, remove infected leaves before it spreads. Two other things may help with controlling the spread: curb nitrogen fertilizers and water plants overhead early in the day.

How do I eradicate powdery mildew? https://extension.oregonstate.edu/ask-extension/featured/how-can-i-eradicate-powdery-mildew

Cucumber, pumpkin, squash powdery mildew  https://hortsense.cahnrs.wsu.edu/fact-sheet/cucumber-pumpkin-squash-powdery-mildew/

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Click here for a printable pdf of this article. Written by Jane Collier, August 2024. Photo courtesy Pixabay