Investigation the Effect of Pre- and Post-Emergence Herbicides on Weed Control and Yield of Groundnut (Arachis hypogaea L.)

In groundnut (Arachis hypogaea L.), less crop canopy during the first weeks of growth favors strong competition with weeds causing significant reduction in yield. To investigate the efficacy of the pre- and post- emergence herbicides in groundnut yield and weed control, this experiment was carried out in Gilan Agricultural and Natural Resources Research and Education Center in 2017. The experiment was laid out in randomized complete block design with three replications. Treatments consisted Pendimethalin (33% EC), Oxyfluorfen (24% EC), Bentazon (48% SL) plus Haloxy fop R methyl ester (10.8% EC), Imazethapyr (10% SL), Trifluralin (48% EC), twice hand hoeing and rice straw mulch + hand weeding. To compare the treatments, EWRC rating scale for visual control and weed number and biomass reduction percentage in each treatment compared to control were applied. Also, the percentage increase of economic (seed) yield of groundnut in each treatment in comparison with control were assessed to evaluate the treatments. The result showed that the highest yield increases of peanut occurred in treatments of Bentazon at dosage of 2 L.ha-1 plus Haloxy fop R methyl ester at dosage of 0.75 L.ha-1 as post-emergence application at 2-5 leaf stage of weeds and twice hand hoeing at times of 3 and 6 weeks after planting with 188.6 and 177.7 % increase of yield compared to weedy control, respectively. In these two treatments the weed control of grass weeds (Echinochloa crus-galli L. and Setaria glauca L.) was 81.5 and 100% respectively, broad leaved weed control (Physalis divaricate D. Don and Amaranthus retroflexus L.) was 84.7 and 93.1 % respectively and sedge (Cyperus esculentus L.) control was 70.2 and 90.4 % respectively compared to control.