Evaluation of Imazapic Applications for Establishment of Southeastern Wildrye

Abstract

Core Ideas Southeastern wildrye can be successfully established using imazapic as a pre‐ and post‐emergence herbicide. Lower rates of imazapic are successful at controlling winter annual weeds, such as henbit and little barley, during establishment of southeastern wildrye. Southeastern wildrye end of season dry matter yields decrease with increasing rates of imazapic. Southeastern wildrye [Elymus glabriflorus (Vasey ex L.H. Dewey) Scrib & C.R. Ball] is a native, cool‐season, perennial grass that shows promise as a forage crop for the southeastern United States. Little is known about the proper methods of establishment for this species, particularly its ability to tolerate pre‐ and post‐emergence applications of imazapic. Replicated field trials were established in Newton and Starkville, MS, in the fall of 2014 and 2015. Pre‐ and post‐emergence treatments included an untreated control, and application rates of 0.035, 0.07, 0.105, and 0.14 kg ai ha−1, which were applied to conventionally seeded plots. Seedling counts and height data were collected at bi‐weekly intervals, along with visual ratings for weed control. End of season dry matter (DM) yields were also recorded for both establishment years. As expected, higher rates (0.105 and 0.14 kg a.i. ha−1) of imazapic caused significant damage to emerging seedlings in both pre‐ and post‐emergence applications. These rates resulted in greater weed control, but ultimately, in reduced DM yields. Lower pre‐emergence application rates (0.035–0.07 kg a.i. ha−1) resulted in acceptable weed control, and minimal seedling damage. Results from these field trials demonstrates the ability to successfully establish southeastern wildrye with the use of imazapic, thus providing beneficial information for the development of this species as a forage crop for the Southeast.