Herbicide Resistant Horseweed in New York and Possible Implications
Mike Basedow, Tree Fruit Specialist
Eastern New York Commercial Horticulture
Horseweed (also called marestail) is a frequently occurring species in New York. It can be found growing in a variety of habitats, including along roadsides, in field crop and vegetable operations, and in berries, grapes, and tree fruit. Often considered a winter annual, horseweed has a wide germination window and seedlings can emerge in the spring, summer, and fall. Herbicide resistance, particularly to glyphosate, is widespread in the US and has recently been identified in New York (see the 2022 summer issue of Fruit Quarterly https://nyshs.org/fruit-quarterly/). Many of these populations were collected from soybean systems where glyphosate is frequently used for managing unwanted vegetation. Two New York populations, collected from a vineyard and an apple orchard in the Finger Lakes Region, were found to be susceptible to glyphosate but resistant to labeled rates of paraquat. Paraquat resistance in horseweed has been formally confirmed previously in Belgium (nurseries), Canada (peaches), Japan (orchards, grapes, roadsides, railways), California (almonds), Delaware (soybeans) and Mississippi (soybeans) (https://weedscience.org/Home.a... ).
Herbicide Resistant Horseweed in New York and Possible Implications (pdf; 1849KB)

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February 4, 2026
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Do you have an idea for a new enterprise to add value to your farm? Maybe you're considering scaling up for a potential market opportunity but just aren't sure if it's a good fit for your business. Join Cornell Cooperative Extensions of Allegany County, Broome County, Madison County, Onondaga County, Niagara County, Tioga County, the Niagara Small Business Development Center, and the Eastern NY Commercial Horticulture Team for a hybrid series on Wednesdays in February, starting on February 4th that will answer these questions and more. Annie's Project seeks to empower farm women through education, networks and resources. We welcome, and encourage, learning and sharing amongst farm women as we help you grow as decision-makers and leaders on your farm.
2026 Eastern New York Fruit and Vegetable Conference
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February 25, 2026 : Tree Fruit Scouting - Online Course
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