Growers Should Monitor Late Blight Closely

Published online: May 11, 2018 Fungicide
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According to Amanda J. Gevens, Associate Professor & Extension Vegetable Plant Pathologist, UW-Madison, 

USAblight.org is again up and running for 2018 in an effort to support the detection and characterization of late blight on tomato and potato crops from the U.S.

Amanda Gevens, an extension vegetalbe plant pathologist at the University of Wisconsin-Madison, says that already this year, late blight has been confirmed on potato and tomato in Florida. In all cases reported to the USAblight website, the pathogen genotype was US-23. This has been the predominant genotype in Wisconsin and across the U.S. in recent years. US-23 can still generally be managed well with use of phenylamide fungicides such as mefenoxam and metalaxyl (i.e., Ridomil).

However, a potato sample from northeastern Florida was sent to Gevens’s lab recently, and the genotype was US-8. This information does pose some additional concern for management, as US-8 cannot be managed with phenylamide fungicides, since isolates are resistant to the fungicide, Gevens says.

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