Efficacy of herbicides against canary grass and wild oat in wheat and their residual effects on succeeding greengram in coastal Bengal

Rice production in coastal Bengal is not satisfactory mainly because of water crisis in winter season. Realizing rapid population growth, it is generally understood that rice alone could not meet the food requirements of this region. Wheat, preferably short duration cultivar, was therefore chosen as an alternative winter food crop. Furthermore, dietary preferences of local people are also changing and wheat is becoming a highly desirable food supplement to rice. However, weeds cause substantial losses in yield and quality of wheat crop in this part of the State. In wheat, weeds alone account for 10 to 80% yield losses depending upon weed species, severity and duration of weed infestation (Jat et al. 2003). Phalaris minor and Avena ludoviciana are major problematic grass weeds causing large scale reductions in wheat grain yield (Chhokar et al. 2012). To attain economic wheat yield, weeds must be removed during critical period of competition which falls in between 0 to 30 days of sowing (Saha et al. 2016). In other words, if the weeds are not controlled at the critical stages of crop growth, they may cause reduction in crop yield upto 66% (Kumar et al. 2011). For controlling weeds in wheat, farmers mostly rely on herbicides due to cost and time effectiveness.