Evaluation of Pre- Emergence Herbicides for Control of Annual Grass and Broad-Leaved Weeds in Finger Millet Elusine Coracana in Kakamega County, Kenya
Mayaka, Justus Mogaka
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Finger millet is an important crop worldwide due to its nutritive and cultural qualities. Production in Kenya has declined due to poor weed management which has always been hampered by heavy rains and also lack of labor for hand weeding. More so because weeding is mostly done outside the critical period of control leading to huge yield losses. This study aimed to evaluate the effectiveness of selected pre-emergence herbicides in control of common annual grass and broadleaved weeds in finger millet production. The specific objectives were; to determine growth and yield of finger millet under different weed control methods; to compare changes in the total weed biomass under different weed control methods, and to determine the effects of pre- emergence herbicide and their rates on grasses and broad leaf weeds. The experimental design was randomized complete block design with three replications. The experimental plots measuring 2 by 2 meters were laid down and the five treatments, that is commercially available pre- emergence herbicides (Pendimethalin, Metribuzin, Atrazine, Metolachlor and Dimethyl amine) were applied at uniform dosages of 1, 1.5 and 2 L/ha per each. The control treatments included plots managed using hand weeding and no weeding. Data was collected on the number of weed species, weed biomass, number of basal tillers, herbicide phytotoxicity, weed and crop heights, number of panicles, weight of panicles, weight of un-threshed and threshed grains and 1000 grain weight. The data was analyzed using GenStat version 15.1 and different means were separated using Tukey‘s test at P<-0.05. Results indicate that all the tested pre-emergence herbicides were effective in the control of annual grass and broadleaved weeds in finger millet than hand weeding and no weeding methods. Application of Pendimethalin at 1.5 and 2.0 L/ha Active Ingredient (AI), resulted in weed optimal control and least phytotoxicity. Results also indicated that the height of finger millet was significant where the herbicides were applied. Lower weed biomass was also positively correlated with higher crop height, more panicles, high unthreshed and threshed weights and a 1000 grain weight. Weed control using pre emergence herbicides significantly (p < 0.001) increased the yields of finger millet. Pendimethalin and atrazine at 1.5 and 2 L/ha rate were the best with regard to the control of annual grass and broad leafed weeds in finger millet. Chemical weeding of finger millet especially by use of pendimethalin at 1.5 and 2 L/ha is therefore recommended. Further studies to determine the effectiveness of these herbicides against the weeds of finger millet in different agro-ecological zones as well as on other varieties of finger millet.