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
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Date
2018-07
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University of Agricultural Sciences, Dharwad
Abstract
The field experiment was conducted at Main Agricultural Research Station. University
of Agricultural Sciences, Dharwad on medium black clay soil during two consecutive years
(2015-16 and 2016-17) in kharif-rabi sequence. Results indicated that pre-emergence
application of alachlor 50 EC, pendimethalin 30 EC, butachlor 50 EC, pendimethalin 38.7 CS
and oxyfluorfen 23.5 EC effectively controlled annual grassy and broad leaved weeds in
groundnut/soybean and had no residual toxicities on all the succeeding crops. Post-emergence
application of quizalofop ethyl 5 EC, propaquizafop 10 EC and fenoxaprop-p-ethyl 9 EC
effectively controlled only annual grassy weeds and they did not show any residual toxicities
on all the succeeding crops. On the contrary, post-emergence application of imazethapyr 10
SL (100 g/ha) although suppressing the growth and development of annual grassy and broad
leaved weeds, but resulted in residual toxicities in succeeding crops. The severity of
imazethapyr residual toxicity on succeeding crops was greater on grain amaranth > sorghum >
wheat > maize > safflower > chickpea. Yield components, dry pod weight/plant, total number
of pods/plant, 100 dry pod weight in groundnut and; total number of pods/plant, seed
weight/plant and 100 seed weight in soybean and B:C ratio were more in treatments which
received pre-emergence herbicides, post-emergence herbicides and weed free check treatment
over weedy check treatment and treatment which received post-emergence application of
imazethapyr 10 % SL @ (100 g/ha). Significantly lower dehydrogenase (μg TPF formed/g
soil/d ) phosphatase (pnp formed/g soil/h) and urease activity (μg NH4-N formed/g soil/d), in
preceding as well as succeeding crops was recorded with post-emergence application of
imazethapyr 10 SL (100 g/ha).