Management of Noxious Weed Johnson Grass (Sorghum halepense) in Sorghum under Semi-arid Region of Rajasthan, India

A three-year field experiment was conducted during the kharif seasons of 2018–2020 in farmers’ fields within agro-climatic zone IIIA of Rajasthan, India, to evaluate post-emergence herbicides for managing Sorghum halepense in sorghum. Five treatments were arranged in a randomised block design with four replications: weedy check, quizalofop-ethyl at 70 g a.i. ha⁻¹, tembotrione at 100 g a.i. ha⁻¹, fluazifop-P-butyl at 200 g a.i. ha⁻¹, and a weed-free treatment. Herbicides were applied at 15–20 days after sowing, and weed density, weed-control efficiency, weed index, grain yield, stover yield, net return, and B:C ratio were assessed. Among the herbicide treatments, tembotrione at 100 g a.i. ha⁻¹ produced the lowest mean S. halepense density at 30 days after sowing and the highest mean weed-control efficiency of 71.39%. It also recorded the lowest weed index of 4.67. The weed-free treatment produced the highest grain and stover yields; however, these yields were statistically at par with those obtained using tembotrione. Tembotrione generated the highest net return of ₹31,312 ha⁻¹ and a B:C ratio of 1.44, exceeding the economic performance of the weed-free treatment. Quizalofop-ethyl and fluazifop-P-butyl caused phytotoxicity in sorghum. Under the conditions of this study, post-emergence application of tembotrione at 100 g a.i. ha⁻¹ provided the most favourable combination of Johnsongrass suppression, crop yield, and economic return among the evaluated herbicide treatments.