Developing a Management Program for Powdery Mildew in Winter Squashes with Resistant Varieties

Powdery mildew is an important disease of winter squash and other cucurbit crops. It occurs throughout New York every year. Management is usually needed to avoid a reduction in yield. Application of fungicides has been the main practice. Several winter squash varieties with resistance to powdery mildew are now commercially available. The source of this gene for resistance is Cornell’s Department of Plant Breeding. Growers need to know how well these resistant varieties perform compared to horticulturally-similar, fungicide-treated susceptible varieties, and whether there are benefits to an integrated program with reduced fungicide inputs (fungicides applied every 14 days compared to the standard 7-day interval). Two experiments were conducted to evaluate acorn and butternut squashes