178 J. Crop and Weed, 13(1) Bioefficacy of pyrazosulfuron and bensulfuron methyl in combination with pretilachlor against weeds in transplanted rice (Oryza sativa l.) under temperate conditions of Kashmir M. ANWAR BHAT, A. HUSSAIN, M. A. GANAI, I. A. JEHANGIR AND N. A. TELI Mountain Research Centre for Field Crops, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Khudwani, Anantnag- 192 102, Jammu and Kashmir Received : 04-01-2017 ; Revised :25-03-2017 ; Accepted: 28-03-2017 ABSTRACT Field experiment entitled “bioefficacy of pyrazosulfuron and bensulfuron methyl in combination with pretilachlor against weeds in transplanted rice under Kashmir conditions” was conducted at Mountain Research Centre for Field Crops, Sher-e- Kashmir University of Agricultural Sciences and Technology of Kashmir during kharif 2014 and 2015. The experiment comprised of six treatments (W 1 :Pretilachlor+Bensulfuron methyl, W 2 :Pretilachlor+ pyrazosulfuron, W 3 :Butachlor, W 4 :Hand weeding twice (15 and 30 DAT), W 5 :Weed free and W 6 :Weedy check) replicated four times in a randomized block design. The results revealed that application of Pretilachlor+Bensulfuron methyl, on an average caused a reduction of 7.44 and 79 per cent in weed population as compared to butachlor and weedy check, respectively. Pretilachlor+pyrazosulfuron application also proved effective in controlling the weeds and reduced their density by 10.25 per cent compared to commonly used butachlor. Among the tested herbicides, lowest weed dry matter of 9.45 (3.22) g m -2 was recorded with Pretilachlor+pyrazosulfuron application. Application of Pretilachlor+Bensulfuron methyl exhibited a superiority of 11.09 per cent in reducing the dry weight of weeds as compared to Butachlor and the corresponding figure for Pretilachlor+pyrazosulfuron was 17.06 per cent. Combination application of Pretilachlor+pyrazosulfuron recorded considerably higher grain yield (7.27 t ha -1 ) than butachlor (6.74 t ha -1 ) and weedy check (4.17 t ha -1 ). The superiority exhibited by Pretilachlor+pyrazosulfuron over butachlor was 7.35 and 7.76 per cent during 2014 and 2015, respectively. Keywords : Bensulfuron-methyl, pyrazosulfuron-ethyl, butachlor, pretilachlor, grain yield, weed control efficiency Rice is the staple food for more than half of the world’s population and life for millions of people especially in Asia, where 90 percent of the world’s rice is produced and consumed. In India rice is grown in about 45 million hectares with a production of about 92 million tonnes. In Jammu and Kahmir, State the rice crop occupies an area of 2.65 lakh hactares with a production of around 454.8 thousand tones out of which Kashmir valley alone accounts for 62 per cent of the production (Economic Survey, 2015). The very low annual growth rate of rice yield observed for the last two decades is a cause for concern with regard to food security. Due to abundant sunshine with nearly pest free environment Kashmir region is suitable for very good rice yields. In spite of this fact the average productivity (around 2.2 t ha -1 ) is far below the potential yields (6-7 t ha -1 ). This lower productivity is due to inappropriate management related to nutrients, weeds and water including low and imbalanced use of manures and fertilizers, faulty irrigation and cultural practices and poor weed control practices. With strategic management of all these factors, the yield gap can be narrowed to improve the rice productivity, food security and the socio-economic well- being of rice growers throughout Kashmir valley. Due to the increasing cost and availability of inputs and labour, rice farming is becoming unprofitable in the valley, as more than 80 per cent of the farmers in Kashmir are either small or marginal. Weed competition is going to be the major constraint in achieving higher productivity. Experiments showed that yields were comparable across all establishment methods of rice when competition from weeds was removed. Thus, weed control is major prerequisite for improved rice productivity and production in all of the rice establishment methods. Weed infestation in rice has been established as one of the important factors responsible for lower productivity as the weed flora under transplanted conditions cause a yield reduction upto 45 per cent (Manhas et al., 2012). Out of the losses due to various biotic stresses, weeds are known to account for 45 per cent of the losses. The effective control measures at initial stage of crop growth can help in improving the productivity of rice. Although a number of pre-emergence herbicides provide good control of grassy weeds but due to continuous use of such herbicides a shift in weed flora and evolution of herbicide resistant weeds has been observed (Rajkhowa et al, 2006). Hence the evaluation of new herbicide molecules for the control of wide spectrum of weed flora is imperative. Recent trend of herbicide use is to find out the effective weed control measures using low dose high efficiency herbicides which not only reduce the total Journal of Crop and Weed, 13(1) : 178-182 (2017)