Downy mildew watch
Fungicides recommended for cucumber disease control
Michigan cucumber and pickle growers have battled downy mildew, incited by the water mould, Pseudoperonospora cubensis, since 2005. Resistant cultivars are not currently available and fungicides have been the only effective means of controlling this disease. This downy mildew pathogen is resistant to commonly used fungicides including Ridomil Gold-based products and the strobilurin fungicides (i.e., Cabrio, Quadris and Flint). Results from our research have identified a limited number of fungicides that are effective, but must be applied every five to seven days to control downy mildew on cucumbers when weather favours disease (Table 1).
Downy mildew spores detected
A significant number of airborne downy mildew spores were detected on June 18, 2014 in the pickle-growing region of Bay County. This was the only day in June with relatively high spore counts. With spore detection and the favourable environmental conditions for downy mildew that we’ve had this summer, Michigan State University Extension suggests a fungicide program take place for cucumbers. There are no confirmed occurrences of cucurbit downy mildew in Michigan or nearby states. There have been outbreaks in Florida, North Carolina and South Carolina.
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