Control of Atrazine Tolerant 'baans gha' (Brachiaria reptans) in Spring Sugarcane

摘要

A field study was conducted at Ladhowal, Ludhiana during 2004-05, 2005-06 and 2006-07 to evaluate alternate herbicides for control of atrazine tolerant Brachiaria reptans in spring sugarcane. Pre-emergence atrazine 1.0 kg (standard), metribuzin 1.4 kg, diuron 1.6 kg and pendimethalin 1.125 kg/ha alone, tank mix of pendimethalin 0.75 kg with atrazine 0.75 and 1.0 kg, metribuzin 0.875 and 1.4 kg and diuron 1.6 kg/ha, three hand hoeings at 30, 60 and 90 days and unweeded control were evaluated in RBD. Atrazine 1.0 kg/ha recorded Brachiaria population and cane yield similar to unweeded control. Metribuzin 1.4 kg and diuron 1.6 kg/ha alone, tank mixing of pendimethalin 0.75 kg with metribuzin 0.875 kg or atrazine 1.0 kg/ha reduced Brachiaria population by 82 to 96% and increased cane yield by 16 to 28% than alone atrazine 1.0 kg/ha. Weed control efficacy under above treatments varied from 67 to 72%, while it was only 12% with atrazine 1.0 kg/ha. Pendimethalin 1.125 kg/ha though reduced Brachiaria density by 89%; however, its lower activity over time resulted in poor weed control efficacy (45%) and similar cane yield to atrazine 1.0 kg/ha. Metribuzin 0.875 kg+pendimethalin 0.75 kg/ha recorded the highest cane yield (76 t/ha), net returns (Rs 48, 200/ha)and benefit: cost ratio (0.840). Different weed control treatments did not influence cane quality. Metribuzin 1.4 kg and diuron 1.6 kg/ha alone, and tank mix of pendimethalin 0.75 kg either with metribuzin 0.875 kg or atrazine 0.75 kg/ha were very effective for control of B. reptans and attaining the highest productivity and profitability in spring sugarcane.