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
2025 New York State Potato School

February 11 - February 12, 2025
Waterloo, NY
This year's program will feature speakers covering critically important topics like disease management, updates in storage techniques, new varieties, and other production management practices. New for this year will be the Processor Panel where guests will have the chance to interact with some of the major chip processors in the northeast. Your participation will also earn you DEC and CCA points.
Remote Good Agricultural Practices (GAPs) Training
February 12, 2025
Join Cornell Cooperative Extension of Orange and Oneida Counties, the Cornell Vegetable Program, Harvest NY, and the Eastern NY Horticulture Team on Feb. 12 for a remote Good Agricultural Practices (GAPs) training. Good Agricultural Practices is a voluntary food safety audit program requiring minimum standards for the production, handling, packing, and storing of fresh fruits and vegetables, and is required by some buyers. Trainers will cover food safety best management practices related to worker training, preharvest assessments and wildlife management, water testing, postharvest handling, hygienic equipment design and efficient wash-pack setups, how to write a farm food safety plan, and more. The training will follow the USDA GAPs audit checklist so that farms will be prepared for an audit. A NYSDAM GAPs auditor will join us to discuss audit logistics and answer questions from participants. Following the course, we will offer a series of virtual office hours to follow up with course participants to assist them with writing their farm food safety plan, which is mandatory for the GAPs audit. Participants will receive a certificate of course completion after the training.
Food Safety Lunch and Learn Webinar Series
February 11, 2025 : Part One: What's Going on with Food Safety?
NYS Department of Agriculture and Markets FSMA inspectors are expected to step up farm visits this season. Why are they showing up on the farm asking about FSMA? Aren't we exempt? This noontime hour we will discuss the purpose of the farm visits and what produce farmers need to know.
February 18, 2025 : Part Two: What Counts as Food Processing?
In this session, we will discuss what counts as processing and what doesn't. Stories of inspectors coming to farmers markets and auctions telling some growers certain products can't be sold usually without much explanation. We will try to make some sense of things and clear up some misunderstandings so hopefully the upcoming season goes smoothly.
February 25, 2025 : Part Three: Traceability - Benefits for Food Safety and Beyond
Can having a traceback process for your produce (and other farm products) make good business sense regardless of FSMA regulations? We will (try to) make the case for farms to have some sort of traceability mechanism in place.