Cucurbit Downy Mildew (CDM) was discovered on cucumbers near Belvidere, Warren County on Friday 7/13. This occurrence is in addition to the previously reported infection sites in Salem County.
All growers statewide, should be adding appropriate downy mildew specific fungicides to their protection programs on cucumbers. Look for yellow “panels” on the upper leaf surface, with dark sporulation on the lower leaf surface.
It should be noted that, in the Belvidere case, adjacent crops of summer squash and muskmelons were uninfected. Additionally, no pumpkin or winter squash fields are known to be infected at this time. Most races of CDM will infect cucumbers, while there are limited strains that will infect other cucurbits like musk and watermelons as well as pumpkins and winter squash.
Please refer to the CDM Forecast http://cdm.ipmpipe.org/ for updates on disease outbreaks and forecasts for this disease. Useful fungicides and rotations are to be found in the 2018 Commercial Vegetable Production Guide Cucumber section.
Source: Rutgers University