By Clint Thompson
North Florida watermelon producers should be starting their fungicide applications.
Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Regional Specialized Extension agent in Live Oak, Florida, emphasized that message during his weekly email to growers in the Suwanee Valley Region.
“I’d say we are usually looking for gummy stem blight. That would probably be the main thing we want to put preventative (sprays) on,” Hochmuth said. “It’s too early for downy mildew, too early for powdery mildew. I would say we’re mostly trying to get ahead of anything that is gummy related.”
Gummy stem blight causes lesions on leaves and stems and leads to defoliation. The disease favors warm, wet conditions.
Hochmuth stresses early-season applications of chlorothalonil (Bravo or other formulations).
“I feel strongly that we should be looking at multiple applications of chlorothalonil early, and often times, a grower might get pressure to change to something else more narrowly focused. What happens is you can’t get back on chlorothalonil once they get fruit size,” Hochmuth said. “I feel like until there’s something identified to force a grower to get away from chlorothalonil in the first three to four weeks that they should stick to chlorothalonil and maybe manzate as an alternative.
“I don’t like the idea of getting into a rotation with a very narrowly focused material because you can’t get back on the chlorothalonil.”