Integrating Cover Crops and Herbicides for Marestail Managment Prior to Soybean

Marestail has become a major weed for soybean producers in Kentucky and throughout a broader geographic range. Its small seed size make this weed particularly troublesome for no-till soybean growers; its prolific, wind-blown seed can disperse far between fields and adjacent natural areas; and its extended emergence period complicates management efforts. In addition to all of these traits, glyphosate resistant biotypes are now widespread throughout the state. Thus, management tactics that integrate other chemical options with cultural practices like the use of cover crops are desirable for this species. This project examines the integration of fall- and spring-applied herbicides with fall-planted winter rye as a cover crop to improve management of marestail prior to soybeans. We are utilizing a site with a heavy infestation of fall-emerged marestail that has historically had spring emergence as well. Results from this project will allow us to make recommendations about best management practices for this species in a winter rye cover crop system, and also elucidate areas for further research to better integrate herbicide applications with cover crops-examples include application timing (i.e. when should soil residual products be applied if cover crops are used?), and species by product combinations (i.e. what herbicides can be applied before or after planting cereal rye and cover crop mixtures without damaging the plants?). A master's student under the supervision of Dr. Haramoto will utilize this project for his thesis research, and we also plan to utilize data collected for this project to leverage federal grant funding with collaborators from throughout the Midsouth and Midwestern regions.