Vol. 7 No. 2
Bio-efficacy of herbicides against complex weed flora in wheat and their residual effects on succeeding crops
Author(s): A. K. KHOKHAR AND A. S. CHARAK
Abstract: Isoproturon, clodinafop and sulfosulfuron alone at 750 g ha-1, 60 g ha-1 and 30 g ha-1respectively and tank mixture of isoproturon at 500 g ha-1 + 2,4-D at 500 g ha-1, isoproturon at 500 g ha-1+clodinafop at 30 g ha-1 and isoproturon at 500 g ha-1 + sulfosulfuron at 15 g ha-1 were evaluated against mixed weed flora in wheat. Tank mix application of isoproturon at 500 g ha-1 + sulfosulfuron 15 g ha-1 was highly effective against both grassy and broadleaf weeds - Phalaris minor, Chenopodium album, C. murale, Melilotus indica, Fumeria perviflora and Coronopus didymus. While clodinafop alone and as a tank mixture with isoproturon effectively controlled grassy weeds only, the tank mix application of isoproturon at 500 g ha-1 + 2,4-D at 500 g ha-1 was effective against broadleaf weeds only. The broadleaf weeds being dominant in the experimental field, the overall weed density and dry matter production recorded at different stages of crop growth was minimum in isoproturon at 500 g ha-1 + sulfosulfuron at 15 g ha-1 followed by isoproturon at 500 g ha-1 + 2,4-D at 500 g ha-1. The tank mix application of isoproturon at 500 g ha-1 + sulfosulfuron at 15 g ha-1recorded grain yield (58.0 q ha-1) similar to tank mixture of isoproturon at 500 g ha-1 + 2,4-D at 500 g ha-1 (55.34 q ha-1) but significantly higher over other herbicidal treatments with an increase of 70% over weedy check (34.10 q ha-1). None of the herbicides alone or in mixture showed residual effect on germination, plant height and dry matter of succeeding crops of green gram and cucumber. The maize crop in succession was adversely affected due to application of sulfosulfuron at 30 g ha-1. Nutrient management with vermicompost at 1.5 t ha-1 and 3.0 t ha-1 along with 75% and 50% recommended dose of fertilizer (RDF) respectively and 100% RDF alone had no significant effect on grassy, broadleaf as well as total weed density. However, weed biomass and grain yield increased significantly with the application of vermicompost over 100% RDF alone..
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