Cucurbit Downy Mildew-Confirmed in WNC (Haywood, Avery, and Henderson County)

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Downy Mildew Management Sprays!

Downy mildew has been found on cucumbers in several WNC counties including Haywood, Avery, and Henderson. Henderson County has several acres in cucumbers, squash, zuchinni, and pumpkins, therefore growers are strongly encouraged to implement management strategies

See photos of leaf symptoms. Typical symptoms include angular, chlorotic or yellow lesions on the upper surface of the leaves with gray to black spores on the underside of the leaf.

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

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 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
Chlorothalonil + oxathiapiprolin Orondis Opti 0 M5+49
Mandipropamid + oxathiapiprolin Orondis Ultra 0 40+49
Cyazofamid Ranman 400 SC 0 21
Famoxadone + cymoxanil (Greenhouse) Tanos 50WG 3 11+27
Chlorothalonil + zoxamide Zing! 0 M5+22
Mancozeb + zoxamide (Greenhouse, Before Disease) Gavel 75WG 5 M+22
Ethaboxam Elumin 4SC 2 22
Propamocarb (Greenhouse) Previcur Flex 6F 2 28
Mancozeb (Greenhouse) Dithane 5 M
Chlorothalonil Bravo/Equus/Daconil 0 M
For the latest fungicide recommendations for cucurbit downy mildew see the Southeastern US Vegetable Crop Handbook. Fungicide labels are legal documents, always read and follow fungicide labels.
To track this disease follow the Cucurbit Downy Mildew Epidemic Status Map.