Symptoms typical of CDM include angular, chlorotic or yellow lesions on the upper surface of the leaves with gray to black spores on the underside of the leaf.
Cucurbit Crop & Disease Management Resources
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August 2020 Michigan Vegetable Updates | MSU Extension
Michigan Cooperative Extension agents from East, Southeast, West, and Southwest Michigan published crop updates on cucumber, melon, watermelon, pumpkins, and winter squashes. Reports of pests include Downy mildew, Powdery mildew, and Squash bug.
Ontario Vegetable crop reports for August 6, 2020
“Downy mildew pressure remains high, and has now been confirmed on cucumbers as far North as Wellington county. Early detection of downy mildew this year increases the possibility of fungicide resistance.”
Yellowing Viruses in Cucurbit Crops
In cucurbit crops, most of the viruses known to cause economically important diseases are transmitted by insects, and many induce foliar yellowing symptoms. These are known as “yellowing viruses.” Most yellowing viruses are transmitted by whiteflies, although at least one is transmitted by aphids.
Ontario Vegetable crop reports for July 30th, 2020
“Examine low lying or poorly drained areas noting any wilted or stunted plants, and look for lesions. Phytophthora usually presents as a foliar blight or a crown rot in zucchini, squash, and pumpkin, so look for dark lesions on the crown. In cucumbers and melons Phytophthora usually causes fruit and stem lesions so look for water soaked lesions with white spores developing on the fruit.”
Ontario Vegetable Crop Report for July 23rd, 2020
“Downy mildew continues to circulate in many parts of Southwestern Ontario, and in American states around the Great Lakes.”
Cucurbit Downy Mildew epidemic updates June 20 to July,20 2020 | ipmPIPE
Cucumber Downy Mildew has now been Confirmed in Ontario
“Downy Mildew was identified today in a commercial cucumber field in Kent County, Ontario. The disease had previously been identified in the Great Lakes area, in Michigan on June 22nd. Risk remains high now that the disease has been confirmed in Ontario despite hot, dry weather.”
