Phyto toxicity and weed control efficiency of castor (Ricinus communis L.) as influenced by weed management practices

Abstract

Field experiment on effect of different weed management practices in castor (Ricinus communis L.) was conducted at the Agricultural College Farm, UAS, Raichur, during kharif 2015 and 2016 in the clay soil. Pooled mean indicated that, application of pendimethalin (38.7% CS) @ 1000 g a.i. ha-1 fb imazethapyr (10% SL) @ 75 g a.i. ha-1 at 30 DAS + IC at 60 DAS was very effective in controlling all types of weeds (3.23, 3.85, 4.07 and 6.54 m2, respectively) and dry weight of weeds (0.74, 0.88, 1.12, 1.82 g m2) at 20, 40, 60 DAS and at harvest. Significantly higher weed control efficiency (72.66%), bean yield (1202 kg ha-1), stalk yield (2718 kg ha-1) and harvest index (30.66 %) were recorded over unweeded check. Application of clomazone (20% EC) @ 750 g a.i. ha-1 as a pre emergent revealed minor phyto toxicity which ranged between 2.0 to 1.0. Hence, sequential application of pendimethalin (38.7% CS) @ 1000 g a.i. ha-1 fb imazethapyr (10% SL) @ 75 g a.i. ha-1 at 30 DAS + IC at 60 DAS is a best weed control method as it recorded higher harvest index whereas application of post emergent herbicides alone was not much effective for the control of weeds and to obtain higher bean yield.