Downy mildew lesions on a cucumber leaf. Photo by Mary Hausbeck, MSU.
The Hausbeck vegetable pathology lab at Michigan State University has established a network of spore traps in major cucumber production areas of their state. This year, they have the ability to distinguish the spores of cucumber downy mildew from the spores of hop downy mildew . The spores of these two mildews look identical. In previous years the Hausbeck lab was not able to distinguish between them. In 2019, by using molecular tools, they know that up until the first week of July, everything that was trapped has been hop downy mildew. Now they have the first confirmation of cucumber downy mildew spores in Allegan County. Although this is the first cucumber downy mildew detected so far and the spore number is low, this is the time of year to be on high alert for cucumber downy mildew disease.
