Answer: It's possible that powdery mildew has attacked the leaves of your zucchini. It happens when air circulation is minimal, nighttime temperatures are low, or the plants are growing in a wet (or humid) environment. You may be able to save your plant and stop the spread of the disease by picking off and destroying the affected leaves. This will also promote better air circulation around the plant. To prevent the problem, be sure to plant your zucchini in a sunny location, don't allow overcrowding, and try not to wet the leaves when you water.
Q&A Library Searching Tips