CHARLESTON — South Carolina watermelon growers should take steps now to protect their crops against powdery mildew.

Symptoms of powdery mildew on watermelon leaves include yellow and brown spots such as seen here.

Symptoms of powdery mildew on watermelon leaves include yellow and brown spots such as seen here.
Image Credit: Anthony Keinath / Clemson University

Anthony Keinath, a plant pathologist at the Clemson University Coastal Research and Education Center, said powdery mildew was found on seedless watermelons growing at there. Because powdery mildew can reduce yields of watermelon and it is still early in the growing season, all watermelon growers in South Carolina should apply a fungicide with specific activity against powdery mildew, he said. Switch and Bravo were two fungicides used on the research plot.

“The research field, where the powdery mildew was found, had been sprayed with Switch on May 4, Bravo on May 4 and with Switch on May 11,” Keinath said. “I recommend using fungicides, such as Luna Experience, Vivando, Quintec or Torino, which were rated better than Switch in recent fungicide trials on powdery mildew on watermelon.”

Symptoms of powdery mildew include yellow and brown spots on watermelon plant leaves. Other symptoms include white mildew growth and short chains of clear powdery mildew spores.

Information on fungicide options are available in the Clemson Cooperative Extension Watermelon Spray Guide for 2016, at http://www.clemson.edu/psapublishing/PAGES/PLNTPATH/IL86.pdf and in the Southeastern U.S. Vegetable Crop Handbook 2016, at http://www.thepacker.com/guides/Pest-production-guides.

A Clemson watermelon research report shows watermelon is the largest acreage vegetable crop grown in South Carolina. Watermelon is produced in all 46 counties. About 80 percent of the watermelons produced in South Carolina are seedless.

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