2022 Cornell Onion Fungicide Cheat Sheets for Control of Leaf Diseases
Christy Hoepting, Extension Vegetable Specialist
Cornell Vegetable Program
This sheet 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.
The 2022 Onion Fungicide Cheat Sheet for Control of Leaf Diseases in New York includes active ingredients, FRAC codes, rating for risk of fungicide resistance, activity on downy mildew, and maximum use rates.
The 2022 Relative Performance of Fungicides Including Tank Mixes for Control of Botrytis Leaf Blight and Stemphylium Leaf Blight Cheat Sheet provides an easy-to-read ranking of the relative efficacy of the treatment options and their FRAC groups.
2022 Onion Fungicide Cheat Sheet for Control of Leaf Diseases in New York (pdf; 302KB)
2022 Performance of Fungicides Including Tank Mixes for Control of BLB and SLB (pdf; 276KB)

Upcoming Events
Fungi, Forage & Forest
June 12, 2026 : Friday Evening
Buckets, Beds & Totems
Explore mushroom cultivation techniques featuring oyster mushrooms, wine caps, and lion's mane mushrooms.
June 13, 2026 : Saturday Full-Day
Wild Edibles
Learn about edible plants and responsible foraging practices focused on plants only (no wild mushroom foraging).
Agroforestry Talk
Discover how agroforestry systems can support farm diversification and sustainable land management.
Shiitake Inoculation (hands-on workshop at Heartland Organics)
Participate in a hands-on shiitake inoculation workshop and learn the basics of log-grown mushroom production.
2026 Muck Onion Growers Twilight Meeting in Oswego
June 18, 2026
Oswego, NY
Open to all Onion Enthusiasts, the Muck Onion Growers Twilight Meeting will include an onion disease research update from 2025, new fungicide recommendations for 2026, an onion maggot seed treatment update, herbicide demonstration tour, and more. This educational event is immediately followed by a catered dinner; both are FREE thanks to generous sponsors!
2.25 DEC recertification credits available in categories 1a, 10 and 23. CCA credits will be offered too.