Integrated Weed Management in Bt Cotton (Gossypium hirsutum L.)

A field experiment was conducted during 2007-08 to 2009-10 at Main Cotton Research Station, Surat involving ten treatments viz., weedy check, cultural practices (HW at 20, 40 and 60 DAS and IC at 45 and 90 DAS) and different rates of herbicides (Pendimethalin and Fluchloralin as pre-emergence and Quizalofop ethyl as post emergence). The experiment was laid out in randomized block design with three replications. The maximum dry weight of weed was recorded at harvest in the weedy check. All the herbicides and cultural operation treatments decreased significantly weed density than weedy check. Low weed density as well as dry weed weight was recorded under Pendimethalin 1.0 kg/ha pre emergence + hand weeding at 30 and 60 DAS tratment, followed by Fluchloralin 0.75 and 1.0 kg/ha pre-emergence with HW at 30 & 60 DAS and 3 HW at 20, 40 and 60 DAS and 2 IC at 45 and 90 DAS. The weed control efficiency was observed highest under treatment of Pendimethalin 1.0 kg/ha + hand weeding at 30 and 60 DAS, followed by Fluchloralin 0.75 or 1.0 kg/ha + hand weeding at 30 and 60 DAS and local practices. The higher weed control efficiency with the above treatment would be attributed due to lower weed dry bio-mass. Growth and yield attributes were affected remarkably due to different treatments. All herbicidal treatments as well as HW at 20, 40 and 60 and IC at 45 and 90 DAS resulted in more number of sympodial branches, bolls per plant and boll weight over weedy check. The highest seed cotton yield was recorded in the treatment of Pendimethalin 1.0 kg/ha + HW at 30 and 60 DAS. In terms of economics, the maximum net monetary returns was accrued under treatment of Pendimethalin 1.0 kg/ha as pre-emergence +HW at 30 and 60 DAS. Thus integrated weed management practice is effective, efficient and economical to control weeds in Bt cotton.