Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
Because of the sudden and destructive nature of cucurbit downy mildew (Pseudoperonospora cubensis), growers need to be warned about a potential outbreak of the disease in their area. In addition, fungicide applications are far more effective if they are made before infection starts. The ipmPIPE forecasts give growers a site-specific risk assessment of disease outbreak 48 hours into the future. This forecast is available at http://cdm.ipmpipe.org. Downy mildew is active in southern Texas as well as Florida and now has been reported in southern Georgia. It is a bit early for Delmarva but growers and fieldmen should get familiar with the site and some of the new features that have been added this season. Updates will be made in Weekly Crop Update but forecasts are made three times a week on Monday, Wednesday and Friday. Delaware is participating in the sentinel plot system associated with this effort. Plots are located at the REC near Georgetown and on the Experimental Farm here in Newark.
Upper leaf surface of cucumber with downy mildew.