Marestail control options for corn and cotton Tom Barber Many calls are coming in on marestail (horseweed) control this week asking: “What can I spray and plant immediately” or “It’s up with my crop now what”? The majority of horseweed in Arkansas is resistant to glyphosate and has been since 2006. It is allelopathic to most crops grown in Arkansas and if left uncontrolled the first 8 weeks can cause significant yield losses. This post provides some options for management in our corn and cotton crops. 4 28 2020 Tuesday, April 28, 2020 2:53:56 PM PDT Weeds,Cotton,Corn,Weed Management,Herbicides Horseweed (marestail) surviving weed control efforts and bolting in an Arkansas production field. kmerritt@uada.edu