Efficacy of Four Herbicide Groups on Weed Control, Growth and Yield of Maize

Abstract

Two field studies were carried out from July 2012 to February 2013 to determine the efficacy of four groups of herbicide on weed control, growth and yield of maize (Zea mays L.) and to investigate the influence of their residual effect on weed succession, rotation crop, soil nutrient status and microbial population at the University Farm, Legon. The experiments, laid out in randomized complete block design, consisted of four replications of eight herbicide treatments from four herbicide groups (Glyphosate: Glyphader, Nwura Wura; Paraquat: Conti-quat, Kwatriqua; Atrazine: Sun-Atrazine, Atranex; 2, 4-D: Sun-2, 4-D, Bextra 2,4-D) applied at two concentrations (lower and higher recommended rates). Glyphader and Nwura Wura, which are glyphosates were applied pre-plant at 1.5 and 3.0L/ha and 2.5 and 4.0L/ha, respectively. Conti-quat and Kwatriqua (derivatives of paraquat) were applied pre-plant at 1.0 and 2.0L/ha and 1.5 and 2.0L/ha, respectively. Sun-Atrazine and Atranex are atrazines and were applied pre-emergence at 3.0 and 4.0L/ha and 1.25 and 2.5L/ha, respectively, whilst Sun-2, 4-D and Bextra 2, 4-D, derivatives of 2, 4-D, were also applied pre-emergence at 2.0 and 4.0L/ha and 1.5 and 2.5L/ha, respectively. The control plots were weeded manually only. Results showed that all herbicides applied increased weed mortality, most especially in the pre-emergence applications. The results also indicated that plants in the control plots had higher crop growth rate and net assimilation rate for low application rate. All herbicide treated plots positively influenced growth and yield of the maize. The highest maize yield per hectare (9779.0kgha -1 ) was obtained in Sun-Atrazine treated plots, followed by Nwura Wura treated plots (9700.0kgha -1 ) and Sun-2, 4-D treated plots (9770.0kgha -1 ). Use of the herbicides positively influenced crop growth and increased biomass yield of both maize and cowpea used as second crop. Results of soil analyses revealed that residual herbicides did not have any negative influence on nutrients status and microbial population of the soil.