By Clint Thompson
The final watermelon harvests in North Florida have growers combatting a plethora of diseases. Those attempting to stretch another picking from their fields this week will have to overcome any number of diseases. These include downy mildew, powdery mildew, Alternaria leaf spot, gummy stem blight and watermelon mosaic.
Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) regional specialized Extension agent in Live Oak, Florida, focused on what diseases concern him the most now and heading into next season.
“I think a lot of these older fields, you can find all of it. It’s been difficult to help the growers prioritize. Surprisingly enough, I think at the end of the year, we’re going to look back and say, we’ve got a new issue with powdery,” Hochmuth said. “Something has happened where it’s a very aggressive strain of powdery. It’s also one that has snuck up on people. It’s not as quickly devastating as downy is, but it sneaks up over a period of time.
“Unmanaged, it can basically defoliate the crop as well. We have some decent materials to fight powdery, but we don’t have excellent materials. That one is a little bit concerning moving forward. Every year it seems to be getting more resistant; a stronger strain of powdery every year.”
Hochmuth said it was inevitable that growers encounter multiple disease situations since they have been harvesting between four and five times out of the same field.
Producers need to stick to a good pesticide rotation program and not exceed the maximum number of applications or total amounts per acre per season. This is important in narrowly targeted fungicides like Orondis Ultra, Ranman, Quintec and Procure. They tend to have resistance build up if overused.