N Save Nature to Survive 9(3): 1135-1137, 2014 www.thebioscan.in 1135 EVALUATION OF DOSES OF NEW HERBICIDE FLUAZIFOP-P-BUTYL 13.4 EC FOR GRASSY WEEDS MANAGEMENT IN IRRIGATED GROUNDNUT BASAVARAJ KUMBAR*, T. V. RAMACHANDRA PRASAD, K. S. SOMASHEKAR, VEERESH HATTI, M. Y. ULLASH, AND V. MADHUKUMAR Department of Agronomy, University of Agricultural Sciences, GKVK, Bengaluru - 560 065 e-mail: Basavaraj4100@gmail.com INTRODUCTION Groundnut is an important oilseed cum leguminous crop in India, but its yield is unpredictable (Bhan and Sing 1993) and it has indeterminate growth habit, hence growth and development of reproductive and vegetative organs overlap, this causes low fruiting efficiency due to inter-organ competition for photo-assimilates and other metabolites(Pushp Sharma AND Virender Sardana, 2012) along with this weed competition for growth factors drastically reduces the yield of groundnut. One of the major factors responsible for low productivity of groundnut is the improper management of weeds. Groundnut is grown extensively during Kharif season under rainfed condition, where it encounters severe weed infestation especially in the early stages. Weeds–the essential component of agro-ecosystems, interfere with crops and lead to enormous crop losses (). The critical period of weed competition is found to be the first four to eight weeks after sowing (Subbaiah et al., 1997 and Jat et al., 2011). Groundnut crop is highly susceptible to weed infestation particularly grasses because of its slow growth in the initial stages up to 40 days (Senthil Kumar 2004), short plant height and underground pod bearing habit. Uncontrolled weed growth reduce groundnut yield to the tune of 76% (Gnanamurthy and Balasubramaniyan, 1998). In agriculture, labour component is becoming scarce, not available at time and prohibitive cost. Chemical control of weeds forms an excellent alternative to manual weeding. However, pre-emergence application of herbicide may allow the emergence of weeds especially grasses after 25-30 days (Jat et al., 2011). At present, many farmers demand post-emergence herbicides for managing weeds, after seeing their menace and other methods could not limit the weeds’ growth. Hence, the present study was, initiated during Kharif 2011 at Hebbal, Bangalore to evaluate the performance of graminicides in relation to pre- emergent Herbicides. MATERIALS AND METHODS A field study was conducted during Kharif 2011, on red sandy loam soil of Hebbal, Bengaluru coming under Eastern Dry Zone of University of Agricultural Sciences, Bengaluru. The soil type was sandy loam with pH of 6.60, average fertility status of 0.65% OC, available N of 228.0 kg/ha, available P 2 O 5 of 24.3 kg/ha and K 2 O of 170.0 kg/ha. The experiment was laid out with eight treatments replicated four times in a randomized block design. The weed management practices evaluated were fluazifop-p-butyl 13.4 EC 100 to 167 g ai/ha, imazethapyr 10 SL 100 g ai/ha, quizalofop-p-ethyl 5 EC at 50 g ai/ha (all applied at 20 DAS), pendimethalin 750 g ai/ha (3 DAS), hand weeding (20 and 35 DAS) and unweeded control. The groundnut cv. TMV-2 was sown at a spacing of 30 cm X ABSTRACT An experiment was conducted to study the effect of new graminicides fluazifop-p-butyl 13.4 EC and quizalofop- p-butyl on growth and yield of groundnut in relation to unsprayed control, hand weeding, pendimethalin and imazethapyr. The new graminicides fluazifop-p-butyl at 134 g, 167 g ai/ha and quizalofop-p-butyl 50 g ai/ha (at 20 DAS) lowered the density and growth of grasses (6.3, 4.3 and 6.0 number/m 2 ) considerably as compared to other treatments. All herbicide treatments recorded the significantly higher nutrient uptake in groundnut as compared to unweeded control whereas, unweeded control lowered the nutrient uptake of groundnut by 44% as compared to hand weeding. The total dry matter production per plant found highest in the treatments Fluazifop-p-butyl 167 g ai/ha (23.5 g) and imazethapyr 100 g ai/ha @ 20 DAS (22.8 g) as compared to other treatments.Fluazifop-p-butyl 134 and 167 g ai/ha gave pod yield (1681 and 1542 kg/ha) similar to that of hand weeding (1655 kg/ha) and was on par with imazethapyr 100 g ai/ha @ 20 DAS (1577 kg/ha), pendimethalin 750 g ai/ha @ 3 DAS (1528 kg/ha) and quizalofop-p-ethyl 50 g ai/ha (1485 kg/ha). Unweeded control lowered the pod yield by 56% (720 kg/ha) as compared to hand weeding. The net return and B: C ratio were higher in fluazifop- p-butyl 167 g ai/ha (Rs. 37,350 and Rs. 1.25) than hand weeding (Rs. 33,010 and Rs. 0.99). for management of weeds in groundnut, the new post-emergence herbicides namely fluazifop-p-butyl 13.4 EC at 134 g ai/ha, quizalofop-p-ethyl 5 EC at 50 g ai/ha (both graminicide at 20 DAS for control of grasses) and imazethapyr 10 SL at 100 g ai/ha (20 DAS, for broad spectrum weed control) appeared good from the point of yield and economics. KEYWORDS Weed management Fluazifop-p-butyl Nutrient uptake Yield and economics Received on : 03.03.2014 Accepted on : 26.07.2014 *Corresponding author