Management of grass weeds with quizalofop in soybean [Glycine max (L.) Merrill]

Post-emergence herbicides are useful for managing weeds in soybean fields. Use of post-emergence herbicide(s) is increasing in India because of the ease of use and control of broad spectrum of weeds. As soybean is a rainy season crop in India, weed control remains an important concern for soybean farmers. An experiment was laid out at Research Farm of Punjab Agricultural University, Ludhiana to study effect of different herbicides for control of grass weeds in soybean. Treatments comprised of post-emergence application of quizalofop 25, 37.5 and 50 g/ha, fenoxaprop 100 g/ha, weed free and unweeded control. Phyto-toxic evaluation of herbicides was carried out on succeeding wheat crop. Quizalofop 37.5–50 g/ha significantly reduced weed density and biomass of grass weeds compared to weedy check. Quizalofop 50 g/ha gave complete control (100%) of Dactyloctenium aegyptium, Digitaria sanguinalis, Acrachne racemosa and Eragrostis spp. till 40 days and > 85% till 80 days after treatment. Quizalopfop 50 g/ha recorded soybean seed yield and yield attributes similar to that of weed free check; it gave highest B:C (2.61) and net returns ($660/ha) All weed control treatments provided higher soybean seed yield compared to unweeded control. Quizalofop at all doses was safe to succeeding wheat crop.