Halosulfuron Methyl: A New Post Emergence Herbicide in India for Effective Control of Cyperus rotundus in Sugarcane and Its Residual Effects on the Succeeding Crops

Halosulfuron methyl (HM) at 67.5, 75.0 and 150.0 g/ha recorded significantly effective in lowering the population (1.2–2.2/m2) and dry weed weight (0.45–0.49 g/m2) of C. rotundus at 60 DAT as compared to other treatments including its lower doses. Atrazine (PE) followed by 2,4-D was not effective against C. rotundus. HM at 67.5, 75.0 and 150.0 g a.i./ha gave 96.3–97.0 % control of C. rotundus as against increase in C. rotundus population (15.1 %) in atrazine (PE) + 2,4-D treatment and 24.4 % increase in untreated check over pre-treatment population. HM at 67.5, 75.0 and 150.0 g a.i./ha recorded higher weed control efficiency (97.8–97.9 %) as compared to atrazine (PE) followed by 2,4-D (8.7 %) and three hoeings (48.8 %). None of the doses of HM affected the dry weight of grassy as well as broad leaf weeds recorded at 60 days after treatment. HM used at 67.5, 75.0 and 150.0 g a.i./ha also recorded significantly higher cane yield as compared to its lower doses, atrazine (PE) followed by 2,4-D and weedy check. Treatment of three hoeings gave maximum cane yield whereas; lowest cane yield was recorded in untreated plots. An increase of 60.9–64.8 % in cane yield over control was recorded when HM was applied at 67.5, 75.0 and 150 g a.i./ha whereas standard check (atrazine followed by 2,4-D) recorded 33.9 % increase. There was no phytotoxicity of halosulfuron on sugarcane in terms of crop discolouration, chlorosis, stunting, wilting, deformation and vein clearing even up to dose of 150.0 g/ha of HM indicating that it was safe to the sugarcane crop. HM was also found safe to succeeding crops (black gram, maize and cucumber) up to 150.0 g a.i./ha dose. Post emergence application of HM 75%WG applied at 52.5, 60.0, 67.5, 75.0 and 150.0 g a.i./ha on sugarcane crop did not affect the germination and yield of follow up crops (black gram, maize and cucumber) during both the years when sown on the same plot after harvesting of sugarcane. Thus halosulfuron methyl 75%WG (Sempra) at 67.5 g a.i./ha at 45 days after sowing was realized to be the optimum dose for effective control of C. rotundus in sugarcane crop.