Bio Efficacy and Phyto Toxicity of Pre and Post Emergence Herbicides on Groundnut Arachis hypogaea L and Soybean Glycine max L Merrill and Residual Effect on Succeeding Crops

Abstract

The field experiment was conducted at Main Agricultural Research Station. University newlineof Agricultural Sciences, Dharwad on medium black clay soil during two consecutive years newline(2015-16 and 2016-17) in kharif-rabi sequence. Results indicated that pre-emergence newlineapplication of alachlor 50 EC, pendimethalin 30 EC, butachlor 50 EC, pendimethalin 38.7 CS newlineand oxyfluorfen 23.5 EC effectively controlled annual grassy and broad leaved weeds in newlinegroundnut/soybean and had no residual toxicities on all the succeeding crops. Post-emergence newlineapplication of quizalofop ethyl 5 EC, propaquizafop 10 EC and fenoxaprop-p-ethyl 9 EC newlineeffectively controlled only annual grassy weeds and they did not show any residual toxicities newlineon all the succeeding crops. On the contrary, post-emergence application of imazethapyr 10 newlineSL (100 g/ha) although suppressing the growth and development of annual grassy and broad newlineleaved weeds, but resulted in residual toxicities in succeeding crops. The severity of newlineimazethapyr residual toxicity on succeeding crops was greater on grain amaranth gt sorghum gt newlinewheat gt maize gt safflower gt chickpea. Yield components, dry pod weight/plant, total number newlineof pods/plant, 100 dry pod weight in groundnut and; total number of pods/plant, seed newlineweight/plant and 100 seed weight in soybean and B:C ratio were more in treatments which newlinereceived pre-emergence herbicides, post-emergence herbicides and weed free check treatment newlineover weedy check treatment and treatment which received post-emergence application of newlineimazethapyr 10 % SL at (100 g/ha). Significantly lower dehydrogenase (and#956;g TPF formed/g newlinesoil/d ) phosphatase (pnp formed/g soil/h) and urease activity (and#956;g NH4-N formed/g soil/d), in newlinepreceding as well as succeeding crops was recorded with post-emergence application of newlineimazethapyr 10 SL (100 g/ha). newline