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Posted 9 July 2008. PMN Crop News.

Downy Mildew Confirmed in Michigan Cucumber Field

Michigan State University.

East Lansing, Michigan (July 3, 2008)--Downy mildew, a highly contagious fungal disease of cucumbers and other vine crops, has been confirmed in a cucumber field in Monroe County.


Mary Hausbeck, Michigan State University (MSU) professor of plant pathology, confirmed the finding July 2. Though the current infection is very light and no fungicides have been applied, Hausbeck recommends that all Michigan cucumber growers should begin spraying for downy mildew immediately and increase their existing field monitoring efforts.

“Cucumber growers are at immediate risk. We need to be scouting fields for other outbreaks of downy mildew because we really need to know where it is so growers can take appropriate actions,” she says.

Hausbeck’s research team has downy mildew traps in three locations on the east side of the state and two in western Michigan. She says spores have been detected in all five traps.

“While the number of spores is low, it tells us our fields have been exposed,” she says. “Because the fungus was already out there, with yesterday’s storm events, the risk is increased. Even in those areas of the state that didn’t receive two-plus inches of rain, there was a lot of wind that will cause the organism to spread.”

Spraying strategies are different for fields that have not shown downy mildew than for those where infections are found. Hausbeck’s recommendations for spray applications in both cases can be found at

“Downy mildew is not a disease where you can afford to sit and see what happens,” she says. “It spreads faster than other diseases that affect cucumbers, and once you have it, it is very difficult to get under control.”

For more information about downy mildew, visit Hausbeck’s Web page at or the MSU Integrated Pest Management Web resources page at

Laura Probyn
517-432-1555, ext. 175