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Weed Control: Pasture and Range

Updated March 11, 2022

Paul O. Johnson

SDSU Extension Weed Science Coordinator

Written collaboratively by Paul O. Johnson, David Vos, Jill Alms, and Leon J. Wrage

There are 24 million acres of native and tame pasture and range as well as 1.4 million acres of grass hayland in South Dakota. Many herbaceous and woody plants are present in these grasslands. Forbs add to the productivity and are desirable. Some may be desirable when found in sparse stands, but become undesirable in heavier stands. Invasive plant species alter the grass species mix and reduce production of palatable forage. Undesirable plants reduce the quality of animal products and still others may be poisonous to livestock. Vigorous grass plants are good weed competitors. Herbicides are an aid to recommended grazing or haying practices. Quality seed, proper seedbed, and good planting techniques will reduce weed problems in new grass seedings.

Herbicide Suggestions

Herbicides are included only after the chemical is registered by the Environmental Protection Agency (EPA) as to residue tolerances in crops used for food or feed. This fact sheet provides a summary of herbicide uses and does not imply a guarantee. Consider the label to be the final guide. Tradenames are for reader convenience. Users are responsible for following label directions and precautions.

Weed Control. Information is based on Agricultural Experiment Station data, other research and observations in South Dakota. Ratings are based on performance using recommended rates and application at proper weed stage and satisfactory growing conditions. Herbicide performance is better if the grass stand is full and vigorous.

Herbicides. Most herbicides are listed by tradename except where the active ingredient is available in several products. The common name (in parentheses) follows the first listing of the tradename. Product labels for the same active ingredient may vary. Consult the label of the product being used.

Rates. Rates for each treatment and each formulation are stated as the amount of product per acre. The amount of active ingredient (ai) or acid equivalent (ae) is also listed for each treatment.

Cost. The cost per acre for low and high rates is listed. Prices do not consider special marketing programs. Consult your dealer/distributer for actual prices.

Time to Apply. Most herbicides for pasture and range are applied when weeds and grass are growing. The optimum growth stage for control of specific weeds is listed in sections of this publication.