Both summer and winter squash can be plagued by many pests and diseases, and plants often die early. For summer squash (Cucurbita pepo), problems include squash vine borers, squash bugs, downy mildew and cucurbit yellow vine disease (CYVD). CYVD is a bacterial disease transmitted by squash bugs that can quickly kill plants as they start to fruit. Losses can approach 100 percent in individual plantings, depending on squash bug numbers. Downy mildew arrives in Georgia in late June or July, and may not be a problem in summer squash in a dry year.
In organic production, the use of resistant and regionally adapted species and cultivars, if available, is the most reliable approach to managing diseases and pests. Most vegetable variety selection and improvement work has not focused on adaption to organic growing conditions in the Southeast. Summer squash and C. pepo winter squash varieties such as pumpkin, delicata and acorn are better adapted to cooler and drier climates. C. maxima winter squash, such as the hubbard and candy roaster types, are also highly susceptible to disease.