Cucurbit downy mildew was reported on watermelon in Dorchester County, Maryland and Sussex County, DE on 7/2.
This is the first report of cucurbit downy mildew in the region to date. The most recent reports of cucurbit downy mildew on the east coast have been in cucumber and watermelon. There are at least 5 or 6 reported races of downy mildew on cucurbit in the US with each affecting a different set of cucurbit hosts. Unfortunately, very little is known about what races may be present in our region.
All cucurbit growers need to scout on a daily basis and consider adding a downy mildew specific fungicide to their regular maintenance programs. To track the progress of CDM in the US please visit http://cdm.ipmpipe.org/. For more information on the control of cucurbit downy mildew please see the 2015 Commercial Vegetable Production Guide.