Control of Annual Grasses Using New Sorghum Herbicides

Weed management trials were established at the Texas Tech New Deal Research Farm in New Deal, TX in 2021 and 2022 to evaluate the efficacy of new sorghum herbicide technologies to control barnyardgrass, large crabgrass, and Texas millet in a non-crop environment. Grass seeds were spread and incorporated with a rod weeder. Visual weed control following preemergence (PRE) treatments were recorded prior to the early-postemergence (EPOST) application. Early- and late-postemergence (LPOST) applications were applied to 10- and 20-cm grasses, respectively. Control of the three grass species did not exceed 69% in 2021 when either rate of imazamox was applied PRE 14 days after treatment (DAT). In 2022, dimethenamid-P controlled barnyardgrass and large crabgrass 94% and 89%, respectively, 28 DAT. Preemergence control of Texas millet did not exceed 70% in either year. In 2021, EPOST applications of quizalofop-p-ethyl controlled all three grass species >90% 14 DAT. Nicosulfuron controlled Texas millet 86% and 89% 14 DAT. Grassy weed control did not exceed 75% when either rate of imazamox was applied in 2021 or 2022. Large crabgrass was controlled 65% 28 DAT in 2022 following nicosulfuron at 0.07 kg ai ha-1. At 14 DAT, quizalofop-p-ethyl at 0.695 kg ai ha-1 controlled barnyardgrass 89% and 93% when applied LPOST in 2021 and 2022, respectively. No treatment exceeded 79% control of large crabgrass in either year. In 2022, Texas millet was best controlled (80%) 28 DAT by quizalofop-p-ethyl at 0.0695 kg ai ha-1. At 14 DAT, Nicosulfuron controlled all grass species up to 75% in 2021 and up to 83% in 2022. In all studies, grassy weeds were most consistently controlled by quizalofop-p-ethyl. These new sorghum herbicide technologies will aid in the control of grassy weeds in sorghum production.