Strategies to Control Competition to Strip‐Planted Legume in a Warm‐Season Grass Pasture

Abstract

ABSTRACTPlanting rhizoma peanut (RP) (Arachis glabrata Benth.) in tilled strips in existing bahiagrass (Paspalum notatum Flüggé) pastures may be an option for establishing legume–grass mixtures in the U.S. Gulf Coast, but management during establishment is not well defined. The objectives were to determine the effect of weed control strategies and N fertilizer on RP establishment in the strip. Treatments were the factorial combinations of six weed control strategies—(i) control (no herbicide and no mowing), (ii) mowing (every 28 d to 10‐cm stubble height), or a single application of herbicides (kg a.i. ha−1) (iii) pendimethalin (0.93), (iv) clethodim (0.10), (v) imazapic (0.07), or (vi) imazapic (0.07) plus 2,4‐D amine (0.28)—and two N rates (0 and 50 kg ha−1 yr−1). Cover (approximately 31%) and frequency (approximately 70%) of RP were not different in imazapic and imazapic plus 2,4‐D treatments, but they were greater than in the other treatments (<10 and 25%, respectively). Light reaching the level of RP in the canopy in imazapic and imazapic plus 2,4‐D treatments was ≥96% of incident light until July and was consistently greater than the other treatments. Nitrogen fertilization following herbicide treatment increased RP cover by 10 percentage points for imazapic and imazapic plus 2,4‐D. Results indicate that imazapic or imazapic plus 2,4‐D offer sufficient control of weed competition to improve establishment of strip‐planted RP, and application of 50 kg N ha−1 increases RP establishment if grass and weed competition is controlled.