Research Finds Multiple Herbicide-Resistant Marestail is Present in New York
Joshua Putman, Field Crops and Forage Specialist
Southwest New York Dairy, Livestock and Field Crops Program

Thirty populations of marestail (horseweed) were collected in the fall of 2020 and are being screened for resistance to commonly used herbicides. Of the 30 collected, 27 appear to be resistant to glyphosate (Roundup) and 28 populations appear to be resistant to cloransulam herbicide, an ALS-inhibitor. This indicates that we have multiple-resistance in NY. It is also suspected that 4 of these 30 samples may be resistant to paraquat (Gramoxone) herbicide. The screening efforts will continue to evaluate the effect of products like 2,4-D and dicamba, Liberty, and PPO-inhibiting herbicides like Reflex and Sharpen.
Upcoming Events
Fecal Egg Count Mobile Workshops Summer 2026 - CCE Allegany County (Belmont, NY)
June 24, 2026
Belmont, NY
Amy Barkley, Livestock Specialist with Cornell Cooperative Extension's Southwest New York Dairy, Livestock & Field Crops Program (SWNYDLFC) will be teaching a series of fecal egg count mobile workshops for those who are interested in the internal parasite challenges affecting sheep, goats, llamas, and alpacas.
Fecal Egg Count Mobile Workshops Summer 2026 - CCE Steuben County (Bath, NY)
June 25, 2026
Bath, NY
Amy Barkley, Livestock Specialist with Cornell Cooperative Extension's Southwest New York Dairy, Livestock & Field Crops Program (SWNYDLFC) will be teaching a series of fecal egg count mobile workshops for those who are interested in the internal parasite challenges affecting sheep, goats, llamas, and alpacas.
Soil Health Field Day
June 30, 2026
Farmersville, NY
Save the date! We're hosting a Soil Health Field Day at Nichols Farm in Farmersville on June 30th. Topics include soil health demonstrations, cover crop uses and benefits, and lunch is being provided. Call 716-699-2377 (ext.106) to RSVP.
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