By Clint Thompson
Florida’s recent diagnosis of downy mildew in lettuce should have Alabama growers on alert about the disease’s eventual movement northward.
Ed Sikora, professor and Extension plant pathologist in the Department of Entomology and Plant Pathology at Auburn University, discusses why producers should be wary of this disease.
“With these moist conditions, that’ll build up the winter nursery for downy mildew down in Florida. Eventually that’s going to come our way in Alabama later in the spring and early summer,” Sikora said. “I think with diseases like downy and some of these problems, especially with how they affect Florida, it will a lot of times determine what might be coming our way later in the season.”
Cucurbit crops are susceptible to the disease. It can destroy plant foliage and cause the leaves to curl and die. The pathogen thrives in wet, humid conditions and requires moisture on the plant surface for spore germination and future infection.
Sikora stresses the importance of growers being proactive and not reactive when managing this disease.
“I would call it a hot button issue or hot button disease. It can move so fast. It’s a very aggressive pathogen under the right conditions. You’ve got this moisture, mild temperature conditions that really spread quickly. If a grower’s not on top of it, doesn’t notice it through scouting or through monitoring or risk assessments by their specialists in their area, the disease can get out of control real fast,” Sikora said. “It’s not a disease you can catch up to. There’s not a lot of products you can come in with half the plant’s gone, start spraying and expect to get a crop.”
Sikora said there are cucurbit downy mildew sentinel plots in Alabama that allow Sikora and other specialists to monitor and keep an eye out for the disease’s development.
Growers can reference the Southeast Vegetable Crop Handbook for what fungicides to apply.