Cooler-than-normal temperatures this spring left South Carolina’s watermelon crop without the heat to fully flourish. According to Clemson Cooperative Extension Service vegetable specialist Gilbert Miller, the daily heat units necessary to grow, develop and ripen watermelons were well below average this year.
“In South Carolina, watermelons need close to 800 heat units from female bloom to ripe fruit,” Miller said. “For 2023, we were about 200 heat units behind 2022.”
Miller and other experts shared this information during the 2023 Watermelon and Vegetable Field Day held recently at the Edisto Research and Education Center.
The significant delay in soil temperatures reaching 81 degrees, resulted in a higher chance for plants to be infected with Fusarium, a disease that causes yellowing, stunting and death of seedlings, as well as yellowing and stunting of older plants.
Clemson Research and Extension vegetable pathologist stationed at the Coastal REC, Tony Keinath, said Delaying transplanting until the soil has warmed to about 81 degrees at a 4-inch depth can reduce the number of plants with Fusarium wilt.
Experts say Fusarium can survive in the soil for up to 5 years. Fusarium wilt of watermelon research continues at the Edisto REC. Bhupinder Jatana, assistant professor of horticulture and vegetable crops, is looking for two growers to participate in a fusarium study.
Growers who are interested can contact Jatana at bjatana@clemson.edu, or call (864) 633-9087.
