A Field experiment was conducted at Agricultural Research Station, Malnoor (UAS, Raichur) during Kharif of 2012-13 and 2013-14 to study the post emergence herbicides on the control of grassy weeds in pigeon pea and its residual effect on the following pigeon pea. The experiment consists of eight treatments viz, propaquizafop 10 EC @ 0.05, 0.062, 0.10 and 0.125 kg/ha, phenoxaprop-p-ethyl 9.3 % at 0.10 kg/ha and imazethapyr at 0.075 kg /ha applied at 2 to 7 leaf stage of grassy weeds. These treatments were compared with hand weeding twice at 20 and 40 days after sowing and weedy check. The data revealed that Imazethayr @ 0.075 kg/ha and hand weeding recorded the highest grain yield of 1683 kg/ha and 1521 kg/ha, respectively. The next best treatment was propaquizafop @ 0.062 kg/ha (1372 kg/ha) and further increase in the dose did not had any beneficial effect. These treatments controlled both the monocot weed species, Dinebra retroflexa and Echinochloa colonum very effectively and had no residual effect on the following pigeon pea.Key words : Bioassay, Pigeon pea and Post emergence herbicides.
INTRODUCTIONPigeon pea ( Cajanus cajan L.) is one of the protein rich legume grown both under irrigated and rain fed conditions. The crop occupies an area of 4.05 million hectares producing 3.27 million tonnes with an average productivity of 799 kg/ha. In Karnataka, It covers an area of 0.59 million hectares with a productivity of 467 kg/ha. Pigeon pea being a medium to long duration crop posed serious problems in the cultivation. In Karnataka, pigeon pea is grown as a mono crop, that is generally sown in JuneJuly and needs inter cultivation to control weeds during August. But due to heavy and continuous rainfall during August, it becomes very difficult to go for inter cultivation in time. The only option and commonly followed method is hand weeding but incessant rains and high cost and not availability of labours at peak periods are the main constrains in controlling weeds in time that reduces yield ( Vyas and Kushwah, 2008). Further, very slow growth of pigeon pea during early stages aggravated the ill effect. Amongst different monocot weeds, Dinebra retroflexa, Echinochloa colonum are the major weeds notice in the UKP area of Karnataka. Hence, it is necessary to tackle the situation with the appropriate post emergent application of herbicides. Therefore, the present investigation was undertaken to study the efficiency of post emergence herbicides for controlling weeds in pigeon pea and its residual effect on the following pigeon peo crop.
MATERIALS AND METHODSA field experiment was conducted at Agricultural Research Station, Malnoor during kharif seasons of 2012-13 and 2013-14. The experiment was laid out in randomized block design with three replications. The soil was shallow to medium deep black clay with pH 8.1, having 243 kg N, 34 P2O5 and 292 K2O per ha. There were seven treatments namely propoquizafop 10% tried at 0.050, 0.062, 0.10 and 0.125 kg/ha, phenoxaprop-p-ethyl 9.3 % at 0.10 kg/ha and imazethapyr at 0...