Assessment of applicability and efficacy of post emergence herbicides through various nozzle systems in wheat (triticum aestivum l.)

In India, the potential yield losses due to weeds in wheat are estimated upto 50 per cent depending upon degree of weed infestation, weed species and management practices. Due to improper application and stage, losses of herbicides increased manifold, be fond of significant reduction in crop yield with adverse effect on soil health. Nozzles used by farmers for herbicide spray, play a vital role in efficacy of herbicides. The efficacy of different nozzle systems viz. hollow cone, even flat fan, twin orifice flat fan, and full cone were assessed for the application of post emergence herbicides in irrigated wheat with a control treatment. The herbicides i.e. sulfosulfuron and 2,4-D were applied after 25 days after sowing of the crop, cv. HD 2864. Sprayer nozzle performance was evaluated in terms of weed density (m-2) weed biomass, plant height (cm), number of effective tillers/plant, grains/spike, wheat grain yield and wheat straw, at farmers’ field in Katni district of Madhya Pradesh during 2007-08 and 2008-09. Statistical analysis indicated that the nozzle type had significant effects on grain yield and dry biomass of weeds. The results revealed that the knapsack sprayer fitted with twin orifice flat fan nozzle for herbicide application, gave better weed control due to its comparatively less spray drift than the others. The weed density was observed highest in the herbicide applied using hollow cone nozzle due to its fine droplet size responsible for high spray drift and lowest in twin orifice flat fan nozzle followed by even flat fan and full cone nozzles respectively. The weed control efficiency of herbicides applied through full cone nozzle was also higher than the hollow cone nozzle. The yield attributes, grain and straw yield of wheat was noted high with twin orifice flat fan nozzle due to its better herbicide efficacy.