Managing Cucurbit Diseases

Tacy Callies Cucurbits, Top Posts

Th appearance of gummy stem blight lesions can vary depending on the type of cucurbit.

By Ernie Neff

University of Florida Institute of Food and Agricultural Sciences doctoral student Andrew Shirley suggested ways to control three cucurbit diseases at Florida Ag Expo in November. Shirley is pursuing his degree at the Gulf Coast Research and Education Center, site of the Expo. He shares highlights of his presentation in an interview with Southeast AgNet’s Tacy Callies.

Shirley says avoiding resistance to control products is a key to downy mildew management. “The best way to deal with resistance management is to rotate modes of action,” he says. “We have plenty of products that work well in controlling downy mildew.” But he says relying solely on any one product will eventually result in the downy mildew pathogen developing resistance to that product.

Addressing powdery mildew, Shirley says biopesticides are not very effective. “But if a grower is interested in avoiding applying some type of chemical products, host resistance is a great approach,” he says. He suggests that growers select a variety that either doesn’t allow powdery mildew to grow or else slows the disease down. He says several modes of action work well in managing the disease.


Finally, Shirley says gummy stem blight lesions vary on different types cucurbits. For example, lesions on watermelon are dark and greasy, while lesions on butternut squash appear raised and bumpy.

To avoid gummy stem blight, Shirley suggests, “At the beginning of the season, make sure that you have healthy transplants (so) you’re starting off clean from the very get-go.” If the plant is infected, he says, “right from the start you’re having to deal with a very aggressive disease.”

Shirley was one of many presenters at Florida Ag Expo, which attracted more than 300 growers and approximately 1,000 total attendees this year.

Hear more from Shirley:

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