Disease detection picked up over the previous week in North Florida watermelons. As observations of bacterial leaf spot and Alternaria leaf spot have been confirmed, University of Florida Institute of Food and Agricultural Sciences is advising growers to scout fields more closely as a result.
“Based on field visits last week, I see the greater concern and recommendation to be on the lookout for bacterial leaf spot,” said Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Regional Specialized Extension agent in Live Oak, Florida, in his weekly email.
Symptoms include black, wet looking spots with black borders. UF/IFAS encourages producers to apply mancozeb plus a low rate of copper where the fungicide applications are warranted. Growers should avoid mixing copper with chlorothalonil due to burn risk. Cucurbit vine crops are very sensitive to copper, especially at rates above 0.5 pounds per acre. Repeated use in watermelon should be avoided unless absolutely necessary.
Neither powdery mildew or downy mildew has yet to be detected in this year’s crop.