last year I had powdery mildew on my cucumbers and winter squash and my Blue Hubbards. I did burn all the vines in the fall. Will Bonide Fung-onil fungicide be able to control the mildew or there is something better? Yes, to apply per the label instructions. Thank You, Stephen Z.
The plants you mention are succeptable to powdery mildew if conditions are ideal. Planting resistant varieties is the best thing you can do. Also allow adequate space between plants for air flow and water in the morning at the base of the plants rather than overhead. If you notice powdery mildew forming fungicide can be used. It should be a sulfur based fungicide that is specific to vegetables. The product you mention is not for edibles. I have attached a link below to an article with more information about powdery mildew. http://www.extension.umn.edu/garden/yard-garden/vegetables/diseases-of-cucurbits/powdery-mildew/