Cucurbit Downy Mildew-Confirmed in Henderson County July 20, 2018

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Downy Mildew Management Sprays!

Downy Mildew symptoms first appeared in Henderson County on July 20, 2018 and was confirmed by Extension Plant Pathologist, Inga Meadows.

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.

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

See adjacent 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.

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.

If you are a Henderson County Grower and suspect cucurbit downy mildew on your farm please contact Karen Blaedow:

Office phone:  828-697-4891
Cell phone:  828-222-3695