Not only is it unappealing, it can reduce a plant’s production of vegetables and impact flavor.
What can we do?
We can control it, but not cure it once it appears. To start, remove the leaves most affected on the pumpkins, zucchini and squash. Throw them in the trash bin next to the rec building not the compost bins.
Don’t compost diseased leaves of any kind.
Next, spread the vine or leaves so the air circulates around the plant. Good sun exposure and good air circulation should inhibit spore germination.
Last year participants in the Family Gardening Program tried an experiment and compared two methods touted online as slowing the spread of powdery mildew.
In one plot, we sprayed the remaining leaves and stem with a cow’s milk spray made with 3 parts whole milk and 7 parts water.
In another plot, we sprayed with a mix of 1 teaspoon baking soda in 1 quart water.
Both methods reportedly create an environment that inhibits the spread of this disease and are best started before powdery mildew appears. In our experience last year, the milk was effective is slowing the progression of the disease.
For Future Reference: Gardeners can purchase resistant varieties at the start of the season. While resistant doesn’t mean the plant won’t get powdery mildew, it does mean they are less susceptible.