Use of Herbicides and Plant Growth Regulators to Suppress Italian Ryegrass Growth

Abstract

Several concentrations of mefluidide (Embark), a plant growth regulator; sethoxydim (Poast), a grass herbicide; and triclopyr (Rely) a nonselective herbicide, were evaluated to determine if italian ryegrass (Lolium multiflorum Lam.) growth could be suppressed. Ryegrass grows prolifically during the winter in states adjacent to the Gulf of Mexico and may serve as a living mulch for strawberry (Fragaria×ananassa Duch.) and other winter crops if its growth can be controlled. Different chemicals and concentrations were screened over 5 years for their efficacy to produce living mulch. Mefluidide produced good ryegrass control but was not evaluated after Study 1 because it is designed for industrial use and does not have an U.S. Environmental Protection Agency fruit crop label. Triclopyr, which has a label for several fruit crops, was studied only in the final year and it provided desired ryegrass control at the 0.016 and 0.030 mL·L-1 (parts per thousand) rate. Prime oil (paraffin base petroleum oil + polyol fatty acid esters) concentration affected results when sprayed with various sethoxydim rates. We concluded that 0.156 mL·L-1 sethoxydim plus 0.25 mL·L-1 prime oil will control ryegrass growth at the desired level (reduce growth by 40% to 50%) for living mulch. These rates are too low to cause much ryegrass browning. Chemical names used: N-[2,4dimethyl-5-[[(trifluoromethyl)-sulfony]amino]phenyl]acetamide, 2-[1-(ethoxylmino)buty1]-5-[2-(ethylthio)propy1]-3-hydroxy-2-cyclohexen-1-one), and ammonium-Dl-homoalanin-4-yl-(methyl) phosphinate.