2017 Cucurbit Downy Mildew Management Guidelines
From Margaret McGrath, Plant-Microbe Biology Section, SIPS, Cornell University
Producing a high-quality cucurbit crop necessitates effectively managing downy mildew. This foliar disease is common in the northeast because the pathogen produces a large quantity of asexual spores that are easily dispersed long distances by wind, which enables it to spread widely. There has been no evidence that the pathogen is surviving between growing seasons where winter temperatures kill cucurbit crops (outdoors above the 30th latitude); however, recently both mating types have been found, albeit typically on different cucurbit crop types, thus there is the potential for the pathogen to produce oospores (sexual spores) that could enable the pathogen to survive in northern areas of the USA. The downy mildew forecasting program has documented based on downy mildew occurrence movement of the pathogen throughout the eastern USA each year via its wind-dispersed asexual spores. The pathogen does not affect fruit directly; however, affected leaves die prematurely which results in fewer fruit and/or fruit of low quality (poor flavor, sunscald, poor storability).
The most important component of an effective management program for downy mildew is an effective, properly-timed fungicide program. And the key to that is applying mobile fungicides targeted to the pathogen starting when there is a risk of the pathogen being present. Mobile (or translaminar) fungicides are needed for control on the underside of leaves. Each year there often are changes to the fungicides recommended as the pathogen develops resistance or new products are registered. Because these fungicides have targeted activity, additional fungicides must be added to the program when there is a need to manage other diseases such as powdery mildew. Most targeted fungicides effective for downy mildew are also effective for Phytophthora blight.
The links below contain more information on resistant varieties, developing a diversified fungicide program and timing your sprays, and recommended targeted and protectant fungicides.
Additionally, you will find information for organic management of cucurbit diseases through biopesticides and fungicides for vegetable crops and herbs.
Effectively Managing Cucurbit Downy Mildew in NY in 2017 (pdf; 175KB)
Biopesticides for Managing Diseases of Cucurbits Organically (pdf; 214KB)
Efficacy of Organic Fungicides for Vegetable Diseases and Herbs (pdf; 158KB)
Upcoming Events
2025 Finger Lakes Auction Winter Growers Meeting
January 2, 2025
Penn Yan, NY
At this grower-focused meeting, ag industry experts will discuss pest control in vegetables, weed management strategies and best practices, seed germination, an introduction to foliar nutrient uptake in vegetables, and grouping flowers by growth needs. Plus we'll hear from a grower panel from Kutztown Produce Auction, moderated with NYS specific pest control from Judson Reid.
2.25 DEC recertification credits will be offered in categories 10, 1a, 23, and 24.
2025 Ontario Produce Auction Winter Growers Meeting
January 15, 2025
Stanley, NY
This grower-focused meeting will include information about pesticide applicator recertification and record keeping requirements, disease control in cole crops and vine crops, and using biocontrols for insect management in greenhouses. Several seed and ag input companies will be on-hand to share product news.
2.75 DEC recertification credits will be offered in categories 10, 1a, 23 and 24. CORE credits (0.5) offered too!
Intro to Food Safety and GAPs Training
February 19, 2025
via Zoom,
This virtual workshop will serve two purposes:
- For produce farms just interested in learning about farm food safety, this program will introduce principles and best practices.
- For produce farms look for a GAPs (Good Agricultural Practices) training needed to meet buyer demands for audit/certification, this program will provide that as well.