Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2025
Publication Date: 2/10/2025
Citation: Tugoo, M.Z., Ramalingam, A.P., Parray, S.A., Kumar, V., Serba, Desalegn D.D., Vara Prasad, P.V., Perumal, R. 2025. Sensitivity of Pearl Millet (Pennisetum glaucum) [L.] R. Br.) Parental Lines to POST Herbicides: Clethodim, Quizalofop-P-ethyl, Imazamox and Nicosulfuron. Weed Technology. http://doi.org/10.1017/wet.2025.11.
DOI: http://doi.org/10.1017/wet.2025.11

Interpretive Summary: Pearl millet (Pennisetum glaucum [L. ] R. ) Br. ) is a climate-resilient crop predominantly grown for forage in the United States. Grass weeds pose significant challenge in pearl millet production. Yet, there are no herbicides labeled for grass weed control in pearl millet. A study was conducted to assess the sensitivity of pearl millet parental lines to different grass weed post-emergence herbicides such as Clethodim, Quizalofop-P-ethyl, Imazamox and Nicosulfuron. The results indicated few pearl millet lines were tolerant to recommended rates of Imazamox and Nicosulfuron. Subsequently, dose-response assays indicated some lines with high survival and less biomass reduction 21 days after application, as compared to a sensitive sorghum hybrid. These assays confirmed the initial report and suggested the potential application of ALS-inhibiting herbicides (Imazamox and Nicosulfuron) for grass weeds control in pearl millet production.

Technical Abstract: Pearl millet (Pennisetum glaucum [L.] R. Br.) is a climate-resilient grain and forage crop. Weeds are a significant constraints for its successful production. The availability of limited herbicide options worsens the challenging grass weeds control. The objectives of this study were to 1) evaluate the sensitivity of pearl millet parental lines to Acetyl-CoA carboxylase - ACCase (clethodim: 136 g ha-1 and quizalofop-p-ethyl QPE: 77 g ha-1), and Acetolactate synthase -ALS (imazamox: 52 g ha-1 and nicosulfuron: 70 g ha-1), and 2) characterize the dose-responses of selected lines to imazamox and nicosulfuron. A total of 56 advanced parental lines underwent testing. Three lines with low sensitivity (ARCH35R, 45R, and 73R) to imazamox, two (ARCH45R and 73R) to nicosulfuron, one sensitive line (ARCH21B) to both imazamox and nicosulfuron, and a susceptible commercial sorghum hybrid - P84G62 (SOR) were subsequently characterized for varying dose responses. Results indicated that all the tested lines were sensitive to clethodim and OPE (only 4 lines showed 2 to 12% survival with 90 to 95% injury at 21 days after application - DAA). Whereas, all tested lines were tolerant to imazamox and nicosulfuron (70 to 100% survival and 5 to 70% visual injury and shoot dry weight reduction at 21 DAA). Dose-response assays revealed that ARCH35R, 45R, and 49R lines had 7.7- to 12.2 and 3.2- to 12.2-fold reduced sensitivity to imazamox when compared to the ARCH21B and SOR, respectively. Similarly, ARCH45R and 49R lines had 2.5 to 6.0 and 1.5- to 3.7-fold reduced sensitivity to nicosulfuron when compared to ARCH21B and SOR, respectively. These results confirm the first report of reduced sensitivity to imazamox and nicosulfuron ALS POST herbicides among pearl millet lines. The findings demonstrated differential sensitivity to ALS-inhibiting herbicides and suggested the potential application of these herbicides for in-season grass weed control.