Abstract

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai during Rabi season of 2011 and 2012 to find out the suitable early post-emergence herbicides to manage the emerged weeds and re-growth of paddy stubbles in rice fallow black gram. The treatments consisted of three levels (50, 75 and 100 g/ha) of early post- emergence herbicides viz., Imazethapyr 10% SL and Quizalofop ethyl 5% EC which were tested alone and in combination and also compared with farmers’ practice of no weeding. Results revealed that lesser weed density was obtained with application of imazethapyr + quizalofop ethyl, each at75g/ha in both the years. Application of quizalofop ethyl alone or in combination with imazethapyr at all the three levels recorded higher weed control efficiency (> 80%) over imazethapyr alone. Higher mean yield of 721 kg/ha was obtained with application of both herbicides each at 50 g/ha and it was comparable with all the quizalofop ethyl treatments as well as application of both herbicides at all the doses. Higher mean net return of Rs.25375/ha was registered with application of both herbicides, each at 50 g/ha. However, higher return per rupee invested (BC Ratio) was obtained under application of quizalofop ethyl alone at 50g/ha during both the years (3.43). Thus, based on the weed control efficiency, seed yield and returns, it could be concluded that application of quizalofop ethyl at 50g/ha on 20 DAS will be effective for controlling emerged grassy weeds and re-growth of paddy stubbles in rice fallow black gram.

Keywords: Imazethapyr, Quizalofop ethyl, Rice fallow blackgram, Seed yield, Weed control efficiency