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)
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Upcoming Events
Orleans Regional Winter Vegetable Meeting
February 9, 2026
Albion, NY
Topics include: Breeding and evaluating tomatoes to control disease and improve yield, jar testing and ensuring spray water quality, breaking down organic matter, FSMA updates and Q&A with Ag & Markets, and industry updates. Includes hands-on learning, coffee break, and sponsor booths.
DEC credits available: 1.0 in CORE plus 0.5 in 1a, 10 or 23
African Eggplant Participatory Breeding Kick-Off
March 5, 2026
Join us to learn about the Cornell African Eggplant Research Project and learn how you can participate! African eggplant, also known as Bitterball, Garden Egg, Kittley and other names, is an important crop for many members of our community with heritage from regions such as sub-Saharan Africa, Southeast Asia, and Brazil. Since 2024, the Cornell African Eggplant Research Project has been collaborating with growers and community partners across New York to develop high-quality varieties adapted to the Northeast U.S. In this meeting, we will share information about growing and preparing African eggplant, highlight our research to date, and invite partners to collaborate with us in our 2026 participatory breeding and variety selection efforts.
COST: FREE! You must pre-register to receive the Zoom link.
Managing the Invasive Swede Midge Webinar
March 6, 2026
Swede midge is an invasive fly that causes serious economic losses to brassica crops. Due to its small size and hidden feeding habits, swede midge is often called an "invisible pest" and damage may be misdiagnosed. In this webinar, we will review the swede midge life cycle and crop damage symptoms, current management recommendations, new research findings, and highlights from on-farm case studies with a focus on organic management.
1.75 DEC pesticide recertification credits in categories 1a, 10, and 23.