Cucurbit Downy Mildew-Confirmed in WNC (Haywood County) August 14, 2020

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Downy Mildew Management Sprays!

Henderson County has several acres in cucumbers, squash, zuchinni, and pumpkins, therefore growers are strongly encouraged to start scouting for downy mildew to ensure early detection.

See photos of leaf symptoms. Before the disease appears apply fungicides at 7-day interval for cucumbers and 10-day intervals for other cucurbits. For example, before disease detection you can use: Tanos + Bravo, alternated with Zampro + Bravo, alternated with Gavel every 7 to 10 days in rotation.

lesions on leaf surface

Angular, yellow lesions on topside of the leaves that are bound by leaf veins. Photo by Charles Averre.

spores on leaf underside

Dark spores of Downy Mildew on underside of leaf. Photo by Gerald Holmes.

Upon detection, growers should use intensive spray programs every 5-7 days, especially if weather conditions are conducive (wet and cool). P. cubensis can become resistant to fungicides quickly and it is important to alternate products and tank mix with with mancozeb or chlorothalonil upon every application. For example, after disease you can use: Ranman + Bravo, alternated with Previcur Flex + Bravo, alternated with Orondis Opti A + Bravo every 5 to 7 days in rotation.
For more information about the disease and how to control it see our  Cucurbit Downy Mildew Fact Sheet.
Example products for cucurbit downy mildew control.
Active ingredient Example product Pre-harvest Interval (day) Fungicide group
Oxathiapiprolin Orondis Opti A 0 49
Cyazofamid Ranman 400 SC 0 21
Famoxadone + cymoxanil (Greenhouse) Tanos 50WG 3 11+27
Ametoctradin + dimethomorph Zampro 0 45+40
Mancozeb + zoxamide (Greenhouse, Before Disease) Gavel 75WG 5 M+22
Mancozeb (Greenhouse) Dithane 5 M
Chlorothalonil Bravo/Equus/Daconil 0 M
To track this disease follow the Cucurbit Downy Mildew Epidemic Status Map.

Written By

Karen Blaedow, N.C. Cooperative ExtensionKaren BlaedowExtension Agent, Agriculture - Vegetable and Small Fruit Call Karen E-mail Karen N.C. Cooperative Extension, Henderson County Center
Updated on Aug 18, 2020
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