2025 Onion Fungicide Cheat Sheet for Control of Leaf Diseases
Christy Hoepting, Extension Vegetable Specialist
Cornell Vegetable Program

The 2025 Cornell Onion (Dry Bulb) Fungicide "Cheat Sheet" for Control of Leaf Diseases in New York provides relative performance rankings for Botrytis leaf blight and Stemphylium leaf blight of the main fungicide options that may be used in New York to control these diseases, based on recent on-farm fungicide trial results, which reflect reduced efficacy of SLB due to development of fungicide resistance. It includes active ingredients, FRAC codes, rating for risk of fungicide resistance, activity on downy mildew, maximum use rates, and photos.
2025 Onion Fungicide Cheat Sheet for Control of Leaf Diseases in New York (pdf; 352KB)

Upcoming Events
Genesee Valley Winter Produce Meeting
January 20, 2026
Farmersville, NY
Fresh market production meeting for small to mid-sized farms. Topics include: fundamentals of plant disease management, keeping yourself safe while spraying (organic & conventional), mushrooms, white mold management, selling at auction, and soil health.
Chautauqua Region Winter Vegetable Meeting
January 30, 2026
Randolph, NY
Fresh market production meeting for small to mid-sized farms. Topics include: vegetable disease management, keeping yourself safe while spraying (organic & conventional), soil and water sampling, managing soil organic matter, grower panel, industry and programmatic updates.
DEC credits available: 1.0 in CORE plus 1.5 in 1a and 23.
Eden Area Winter Vegetable Meeting
February 4, 2026
North Collins, NY
Join us for a mix of industry updates, crop protection talks, pesticide safety programming, and fertility management discussions. This meeting is jointly hosted by the Cornell Vegetable Program and Timac Laing-Gro.
1.25 DEC credits available in CORE plus 1.75 in 1a and 23.