Along the coast of South Carolina, cucurbit downy mildew usually shows up after May 1.4 Spraying for Cucurbit Downy Mildewįungicides are necessary to manage downy mildew on all cucurbits grown in South Carolina in summer and fall. Trellising does not help manage downy mildew. They still produce marketable fruit when they have downy mildew, so they do not need to be sprayed as often or with “high-end” fungicides, and protectant fungicides might be enough. Summer squash, zucchini, and acorn squash tolerate some downy mildew.‘Bristol’ is a new slicer with partial resistance. 3 Downy mildew will develop slower on partially resistant varieties than on susceptible varieties. Choose cucumber varieties with resistance to downy mildew see the Southeastern U.S.Crops planted as early as possible after the last predicted frost may not need to be treated with fungicides. This disease is a greater threat to summer and fall crops than to spring crops. Cultural Practices to Limit Cucurbit Downy Mildew The site also predicts where spores will spread from known sources and where weather will be favorable for a new outbreak in the next 48 to 72 hours. The Cucurbit Downy Mildew Forecast map () shows where downy mildew has been reported in the current year. After infection, downy mildew will continue to spread, even in dry weather, if temperatures stay above 60☏.
Rain, dew, or fog makes infection likely. Rainwater washes spores out of the air onto leaves. Outbreaks of cucurbit downy mildew are most likely to occur during mild, wet weather. Spores move farthest and fastest during cloudy, windy weather and can be blown over 600 miles in 48 hours! Cucurbit downy mildew can also be spread through diseased transplants. In the spring, wind blows downy mildew spores northward from the South. How Cucurbit Downy Mildew SpreadsĬucurbit downy mildew survives over winter on crops growing in southern Florida and Texas where cucurbits do not freeze.
Because it is the only strain that attacks squash, it is sometimes called the squash strain. Strain 1 mainly attacks watermelon, pumpkin, and squashes. 1 Strain 2 attacks cucumber, cantaloupe, and honeydew and is sometimes called the cucumber strain. There are two strains of cucurbit downy mildew, strain 1 (old) and strain 2 (new). Downy mildew on the bottom of infected leaves.
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