Powdery Mildew

A delightful little fungus called powdery mildew has graciously decided to descend upon my garden in these final days of the growing season. The plants affected, members of the cucurbit family, include my zucchini, yellow squash, and the pumpkins.

The infection tends to occur when conditions involve a combination of high humidity around the plant and water that collects on the leaves and is not dried off in a timely manner. Warm days and cool nights (typical Pacific Northwest conditions) encourage its growth. For an idea of what the infection looks like, imagine someone coated the leaves of your plant with a fine dusting of flour, or the first glimmering frost of winter to come has settled upon their normally green surface. Here's a glimpse of the affected yellow squash:
Not a pretty sight

Had I arrived at this plant sooner, I would probably have had a good shot of containing the fungus. By this point the plant is almost entirely covered in the dusty, white spores. The best treatment is of course prevention; growing in as sunny a spot as possible, not crowding the plants to allow adequate ventilation, and, even when the disease arises in spite of following these guidelines (as it did for me) eliminate the infected regions as soon as they are noticed.

With the exception of a few new leaves still green with new growth, this plant looks pretty sickly. Though it's late in the season, it may have a chance to produce a few more fruits, so I decided to perform a drastic surgery to try to eradicate the powdery mildew. My tool of choice: a sharp pair of scissors.

As I said, a pretty drastic procedure, but the infected leaves seem to be dealt with. As the season goes on, I will continue to monitor the plant to check for the return of the mildew, but for now it should be safe.