Evaluation of Different Weed Control Techniques in Soyabean (Glycine max L.Merr) Production

Abstract

Field trials were conducted at the National Centre for Agricultural Mechanization Research Farm, Ilorin (8026’N; 4030’E and 370m above sea level), in the southern Guinea savannah agro-ecological zone of Nigeria, during the 1999 and 2000 cropping seasons, to evaluate the effectiveness of different weed control treatments in soyabean production. Ten weed control treatments consisting of wheel type weeder [3 and 6 weeks after planting (wap)]; hoe weeding (3 and 6 wap); Pre-emergence application of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] + prometryn [N, N’-bis (1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] (Codal)3 at 1.0kga.i./ha; imazaquin{2-[4,5-dihydro-4-methyl-4(1-methylethyl)-5-oxo-1H-imidazol- 2-y1]3-quinoline carboxylic acid} at 0.18 kg a.i./ha followed by (fb) fluazifop-butyl{butyl 2-[4-(5-trifluoromethyl)-2-pyridyloxy] phenoxy propanoic acid} (Fusilade) at 0.25kg a.i/ha; Codal fb wheel type weeder; imazaquin + pendimethalin [N-(1-ethylpropyl)-3,4- dimethyl-2,6-dinitrobenzenamine] (Squadron)4 at 1.1kg a.i/ha; Squadron at 1.1kg a.i./ha fb wheel type weeder; imazethapyr [(±) 2- [4, 5-dihydro-4-methyl-4- (1-methylethyl) - 5- oxo-1H-imidazol-2yl]5-ethyl-3 pyridine carboxylic acid] + pendimethalin (Pursuit Plus)5 at 1.1kg a.i./ha; Pursuit Plus at 1.1kg a.i./ha fb wheel type weeder and no-weeding as control,
were tested. The experiment was laid out in a randomized complete block design with four replications. Pre emergence applications of Squadron, Pursuit Plus, Codal, each followed by wheel type weeder, respectively, and imazaquin fb fluazifop-butyl were the best treatments in terms of weed control while in terms of phytotoxicity to crop, pursuit plus was moderately phytotoxic to soybean, whereas imazaquin fb fluazifop-butyl was the
least phytotoxic. The grain yield results for the two years consistently demonstrated that the wheel type weeder (3 and 6 wap), imazaquin fb fluazifop-butyl, Squadron fb wheel type weeder were as good as two hoe-weedings, effectively suppressing weeds throughout the growing season for the crop. The results suggest that the wheel type weeder is capable of replacing hoe-weeding on small to medium scale soyabean farms as a faster and equally effective weed control practice. The results also suggest that preemergence application of imazaquin fb fluazifop-butyl and pre emergence squadron fb wheel type weeder would be particularly promising for weed control in large scale soyabean production in terms of effectiveness, timeliness and speed of weed control operation.

Key words: Wheel type weeder, imazaquin, imazethapyr, Pendimethalin, Codal, Pursuit Plus, Squadron, Weed control rating.