Disease Supplement – UWEX Vegetable Crop Updates Newsletter
The late blight that was detected in Adams County WI is of the US-23 genotype/strain. This means that phenylamide fungicides such as metalaxyl and mefenoxam (ie: Ridomil) are effective in managing late blight. Other traits of US-23 include, A1 mating type, host range includes tomatoes, produces many relatively smaller sporangia (spores). This was the predominant type in the US last year.
Potato & Vegetable Pathologist
University of Wisconsin