By Karla Arboleda
After some growers reported seeing center rot, downy mildew and Botrytis leaf blight in their fields, University of Georgia (UGA) researchers are working on better disease control for Vidalia onions.
UGA researchers work with both organic and conventional Vidalia onions to develop ways to deal with fungal and bacterial diseases. Bhabesh Dutta, an Extension vegetable pathologist at UGA, discussed updates with Vidalia onion research in 2019.
“We did on-field fungicide spray trials against downy mildew, and we identified a couple of different spray programs that can (help growers),” Dutta said, listing it as one of several issues that regularly affect Vidalia onions in Georgia. “(Downy mildew) was more moderately widespread.”
Sometimes a combination of management strategies is best, Dutta said. Researchers evaluated what would work best to help to manage center rot in the specialty crop.
“The bactericide management program that overlapped with a thrips management program provided better control (in) field and storage compared to the same bactericide program that did not include any thrips management program,” Dutta said.
To get more research done on pathogens, several institutions have partnered to work on the issues. UGA researchers received a grant from the U.S. Department of Agriculture to study center rot, a bacterial bulb rot, in different kinds of Vidalia onions.
“A multi-disciplinary team of scientists from different institutions will work on mitigating the bacterial bulb-rot issue in field and storage,” Dutta said. “We will develop diagnostic assays that will differentiate pathogenic vs. non-pathogenic bacterial strains (and) also evaluate several key components in onion production systems that will mitigate bacterial bulb rot.”
In addition to finding better options to combat downy mildew, Dutta listed fungicides to help with more pathogens. The ideal management would include managing foliar fungal diseases such as Botrytis leaf blight, Stemphylium leaf blight and purple blotch.
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