The Use of Fall Residuals for Ryegrass Management Ahead of Soybean.

Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] has become more problematic and difficult to control because it is resistant to multiple herbicides. Fall-applied residual herbicides have effectively controlled other winter annual weeds and could be another option in controlling Italian ryegrass. The objective of this study was to evaluate multiple residual herbicides for the control of Italian ryegrass in the fall and the following spring before planting soybean [Glycine max (L.) Merr.]. Before any weed emergence, a field experiment was initiated at the University of Arkansas System Division of Agriculture's Jackson County Extension Center near Newport, Ark., in the fall of 2021. Treatments in this experiment consisted of Anthem® Flex (4 fl oz/ac), Command® (20 fl oz/ac), Dual Magnum® (1.33 pt/ac), Outlook® (16 fl oz/ac), Prowl® (2.1 pt/ac), Treflan® (2 pt/ac), Warrant® (2.5 pt/ac), Warrant® (5 pt/ac), and Zidua® SC (3.75 fl oz/ac). Initial visual control of Italian ryegrass 14 days after application (DAA) (28 Oct. 2021) exceeded 95% for every herbicide treatment except for Prowl and the low rate of Warrant. Only Zidua SC, Anthem Flex, and Dual Magnum retained effective residual control at 60 DAA (13 Dec. 2021) (>95%) and 166 DAA (29 March 2022) (>90%). Overall, using Zidua SC, Anthem Flex, and Dual Magnum herbicides were the most effective options to control Italian ryegrass in the fall and following spring before planting soybean. These fall-applied treatments would improve overall Italian ryegrass management and delay the evolution of resistance to postemergence herbicides. [ABSTRACT FROM AUTHOR]