2017 Cucurbit Downy Mildew Management Guidelines

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
Chautauqua Winter Vegetable Meeting

February 10, 2023
Clymer, NY
Meeting will feature growers from Ohio sharing their production know-how and thoughts on food safety. Other topics include weed control, pesticide safety, and the impact of poor crop nutrition. 0.75 DEC credits in 1a, 23 plus 0.5 in CORE, which is good for all categories. Trade show booths available.
Meeting cost is $20/person, includes snacks and educational materials. Registration required by 4 pm on Friday, February 3.
Orleans Regional Vegetable Meeting

February 15, 2023
Albion, NY
Offering presentations in pesticide safety, tips for managing diseases in vegetable crops, how to attract beneficial insects to your field, herbicide options for cole crops, and strawberry disease information. Meeting cost is $10 per person, payable at the door via cash or check. Pre-registration requested by 5:00 pm on Monday, February 13.
DEC credits available: 2.25 in 1a and 10; 2.0 in 23; 1.5 in 22; and 0.5 in CORE (used in all categories)!!
NYS Processing Vegetable Industry Roundtable Meeting

March 15, 2023 : Morning Session: Snap Beans, Sweet Corn, and Peas
Batavia, NY
Processing vegetable industry members who grow, manage, or support snap bean, sweet corn, or pea production for Nortera and/or Seneca Foods, should attend this session of the roundtable meeting. You will:
- Network at this in-person meeting.
- Learn the results of industry-funded research.
- Have a voice in Cornell research and extension.
- Earn 2.0 DEC credits in categories 1a, 10, 23 and CCA recertification credits.
This FREE event is followed by lunch! Pre-registration requested.
March 15, 2023 : Lunch Break and Networking
Lunch is FREE to anyone attending either the Morning Session or the Afternoon Session of the NYS Processing Vegetable Industry Roundtable Meeting. Registration is required.

March 15, 2023 : Afternoon Session: Beets and Carrots
Batavia, NY
Processing vegetable industry members who grow, manage, or support beet or carrot production for Nortera, Seneca Foods and/or Love Beets, should attend this session of the roundtable meeting. You will:
- Network at this in-person meeting.
- Learn the results of industry-funded research.
- Have a voice in Cornell research and extension.
- Earn 2.0 DEC credits in categories 1a, 10, 23 and CCA recertification credits.
Lunch is provided before this session. It's FREE! Pre-registration requested.