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Sudan Journal of Agricultural Research

Herbicidal efficacy of glyphosate on weed control in fallow fields as affected by some adjuvants and 2, 4-D

Osman, A.S., Dawoud, D.A., and Babiker, A.G.

Abstract

Field and greenhouse experiments were conducted at the Gezira research station to study the efficacy of glyphosate on fallow weeds as affected by some adjuvants and tank mixing with 2,4-D. The results showed that glyphosate alone at 0.27 kg a.e./fed displayed 95, 80 and 55% control of grasses and 56 -75% of broad leaved weeds in comparison to untreated control at 2, 4 and 6 weeks after application, respectively. Ammonium sulphate (AMS) or oil adjuvants have poor effects on weed control when added alone; however, they considerably increased the efficacy of glyphosate irrespective of its rate. The addition of AMS or oil to glyphosate at 0.27 kg a.e./fed displayed 78 - 100% and 69 - 87% control of grasses and broad-leaved weeds throughout the season, respectively. Likewise, adjuvants also broaden the spectrum of weeds controlled by the herbicide. R. memnonia was moderately controlled by glyphosate alone at 0.27 kg a.e./fed while the same rate resulted in an excellent control of the same species by the addition of AMS or oil with high persistent effect. Glyphosate alone at 0.18-0.36 kg a.e./fed was more effective on grasses than broad-leaved weeds, while 2,4-D alone was effective on broad-leaved weeds but had no effect on grasses. Mixing both herbicides broaden the spectrum of weed control. Under field conditions, glyphosate alone at 0.36 kg a.e./fed resulted in an excellent control of grasses with high persistent effects, while it has good effects on broad-leaved weeds (70% control) with low persistent effects. 2,4-D alone at 0.36 kg a.e./fed resulted in poor control of grasses and an excellent control with high persistent effects on broad-leaved weeds. However, when the herbicides were tank mixed, excellent control with high persistent effects of both grasses and broadleaved weeds was achieved. Under greenhouse conditions, glyphosate alone at 0.36 kg a.e./fed gave < 50% control of X. strumarium, but when it was mixed with 2,4-D at 0.16 kg a.e./fed an excellent (100%) control of the weed was obtained.

Sudan Journal of Agricultural Research Vol. 15 (2010) PP. 89-102