By Clint Thompson
The recent cold, rainy and windy conditions present across the North Florida region were not ideal for the area’s watermelons. All were ideal for the development of bacterial leaf spot disease.
Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Regional Specialized Extension agent in Live Oak, Florida, said producers should start adding a low rate of copper to their fungicide spray program, but only if there are symptoms of the disease present in their fields.
“There’s one disease in particular that likes cold, wet conditions early in the season and that’s bacterial leaf spot. We have confirmed incidence of bacterial leaf spot since the cold, rainy period,” Hochmuth said. “We’re basically recommending the low end of the labeled range for their copper spray program. That’s where we suggest that to be used. It’s not in all fields by any means, but in fields where this is present, that’s our recommendation.
“I do not like to have copper sprayed unless there’s a justification for it. It’s not one that I am typically going to be excited about as a preventative. If fields have been clean and they’re not seeing any signs of that particular disease, then I would not suggest spraying copper. Copper is really tricky on watermelons. It can be toxic, and that’s why we stick to the low end of the recommended range. It can stunt watermelon plants.”
Hochmuth advises growers in his weekly email that the low rate of copper should be 0.5 pounds per acre.