Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu
Downy mildew on processing cucumber was found on Thursday, June 13, 2018 in Dorchester County, MD. This is one of the earliest occurrences of downy mildew in Maryland. Protect cucumber crops with products that are specific for downy mildew. Among the specific fungicides for this disease are Orondis Ultra or Ranman, which should be mixed with a protectant fungicide. Many additional fungicides are registered for downy mildew and are listed in the Commercial Recommendation Guide. Remember to rotate products in different FRAC groups and to apply preventative fungicides, which are more effective than “rescue treatments”.
At this time, only cucumber (both processing and fresh-market) should be affected. The strains that infect other cucurbits have not been observed in our region.