Acetochlor is a herbicide that is widely used to control weeds in corn, soybeans, and sugar beets in Minnesota. Common trade names for acetochlor products include Harness, Keystone, SureStart, Surpass, Volley and Warrant*. In 2021, it was applied to 59% of Minnesota corn acres, making it the second-most-used corn herbicide in the state in terms of acres covered (NASS USDA). Acetochlor is registered in Minnesota for use on field corn, popcorn, production seed corn, silage corn, sweet corn, soybeans, sugar beets, sorghum, and alfalfa, depending on the specific product.
Acetochlor is in the chloroacetanilide class of herbicides which also includes dimethenamid and metolachlor. It is in herbicide Site of Action Group 15 (long-chain fatty acid inhibitors) and controls weeds by inhibiting growth of seedling shoots (Herbicide Mode of Action Classification Poster). Acetochlor is effective when applied before weeds germinate; therefore, it is typically applied just before or after planting or as a companion with a post herbicide such as Roundup to provide residual action. Acetochlor provides good control of most annual grassy weeds and a number of annual broadleaf weeds. Its control of perennial weeds is limited to yellow nutsedge (Weed Control Guide for Field Crops | Michigan State University). It is often used in combination with other herbicides to obtain broad-spectrum weed control. Atrazine, Flumetsulam and Clopyralid are the most common premix partners with acetochlor (Table 3).
Many other preemergence corn herbicides provide weed control similar to acetochlor including dimethenamid-P (Outlook, Slider), S-metolachlor (Charger, Dual II Magnum, Cinch), flufenacet (Axium) and pendimethalin (Prowl)* (Trials comparing herbicide systems for weed control in field corn have been conducted at the University of Minnesota. Visit Research Reports | University of Minnesota for more information).
Acetochlor is currently not a Restricted Use Pesticide (RUP); therefore, no special certification is needed for its use unless it is being applied for hire or if it is being used in combination with an RUP such as atrazine. If acetochlor is being applied for hire or used in combination with an RUP, pesticide applicators need to be licensed or certified by the MDA, a process which includes passing an exam on proper pesticide use. See Pesticide Applicator Licensing to learn more about the different licenses and certifications. If you offer for sale or sell RUPs and/or bulk pesticides to Minnesota end users you must have a pesticide dealer license.
* No endorsement is implied and no discrimination is intended in the referencing of commercial products or trade names.
