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Strategies to control competition to strip-planted legume in a warm-season grass pasture

Abstract:

Planting 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. © Crop Science Society of America All rights reserved.