By Clint Thompson
Powdery mildew is one of the most problematic diseases that Florida cucurbit farmers must overcome every season. However, fungicides are available that help mitigate the disease’s impact.
Amanda McVay, a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) graduate student, discussed those fungicide options at the Citrus & Specialty Crop Expo on Aug. 13 in Fort Myers, Florida. She emphasized that growers rotate their chemical applications which decreases the likelihood of resistance developing.
“Continuing to spray the same mode of action repeatedly puts a selection pressure on the population. And then once you get that resistance emerging in the population, it can persist,” McVay said. “It’s really best to prevent that resistance from developing. We can do that through rotating modes of action. Thankfully, there are a lot of modes of action that are available and effective for controlling powdery mildew.
“I think growers are pretty well versed in rotating their modes of action. I think sometimes if you’re using pre-mixes, it’s good to make sure that that pre-mix might overlap with the same mode of action several times. So just kind of looking at programs and making sure that you’re incorporating as many modes of action in a cost-effective way as possible.”
Vivando Effectiveness
One of the most effective chemical options is Vivando, which performed well in lab and field studies.
“It was highly effective. In the lab assay, so all of the isolates that we examined were sensitive to Vivando,” McVay said. “In the field, the performance was good. It wasn’t the best performing product, but it was one of the top performing products.”
Disease Background
Powdery mildew is a disease that all cucurbit farmers need to be familiar with. Unlike other pathogens that need wet, rainy conditions to flourish, powdery mildew prefers a drier environment.
“I would say on cucurbits it’s a pretty common pathogen. It comes and goes, and it might not be the most concerning. Another concerning fungal pathogen on cucurbits is anthracnose and gummy stem blight,” McVay said. “There are a lot of different fungal pathogens that our growers are battling, but this is one that is thankfully easily managed with tools that are available.”