Controlling winter annual weed infestations in alfalfa stands is a key to harvesting quality forage. Some common winter annuals that infest alfalfa in the fall are henbit, purple deadnettle, common chickweed, pennycress and downy brome, and other bromegrasses. Good fall weather not only helps alfalfa stands become healthier during the winter but encourages weeds as well. If these weeds are ignored, they are likely to haunt us in the spring.
ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS.
Weed Control in New Alfalfa Stands
If you anticipate winter annuals to be an issue in your new alfalfa stand, then consider applying Balan® DF Herbicide and Eptam® 7E Selective Herbicide preplant and incorporated. Pursuit® Herbicide can be used post emerge in the fall (past 2nd trifoliate leaf stage) to help control winter annuals. Pursuit® Herbicide also has residual soil activity that carries over into spring to help manage weeds. Consult the labels for these herbicides for approval of and application timing in your state.
Controlling Winter Annuals in Alfalfa
Metribuzin 75DF Herbicide can be applied in the fall after growth ceases or in the spring before new growth begins to help control or suppress (dependent on weed species) labeled weeds. Consult label for approval of and application timing in your state.
Sinbar® WDG Agricultural Herbicide can be used for the control or suppress (dependent on weed species) labeled weeds in alfalfa established for one year or longer. A single application can be applied in the fall after plants become dormant or in the spring prior to new plant growth. Consult label for approval of and application timing in your state.
Velpar® DF CU Agricultural Herbicide can help manage (control or suppress depending on weed species) winter annuals in the winter or spring (depending on state). Consult label for approval of and application timing in your state.
Spring control of winter annuals is a gamble because of the narrow application window. In addition, soil conditions and high winds can prevent farmers from spraying the field prior to alfalfa green up.
Grass Weed Control Year-Round Options
Poast® Herbicide, Poast Plus® herbicide, and Select® 2 EC Herbicide can help manage (control or suppress dependent on species) winter annual species throughout the year. Consult labels for approval of and application timing in your state.
Residual Control of Annual Weeds
Warrant® Herbicide is a residual herbicide that can be applied after spring green-up or re-growth for the control of annual grasses and annual small-seeded broadleaves. Warrant® Herbicide does not control emerged weeds.
Contact your state agricultural university or pesticide retailer for information regarding labeled alfalfa weed control in your area.
Whether its weed control in alfalfa or selecting the right Channel® Products to help maximize yield potential on your farm, find your local Channel Seedsman on line at https://www.channel.com/en-us/find-your-seedsman.html.
Loux, M.M., Dobbels, A.F., and Reeb, B. (The Ohio State University), Johnson, W.G., Young, B.G., and Ikley, J. (Purdue University), and Hager, A. (University of Illinois). 2019. 2019 weed control guide for Ohio, Indiana, and Illinois. Pub# WS16/Bulletin 789/IL15. Purdue University, University of Illinois, and The Ohio State University.
Anderson, B. Controlling winter annuals in alfalfa this fall. CROPWATCH. University of Nebraska-Lincoln. https://cropwatch.unl.edu/.