Potency of five pre-emergence herbicides for weed control in cocoyam (Colocasia esculenta (L) Schott) production in Umudike, Abia State
This study was conducted at the National Root Crops Research Institute, Umudike, Abia State in 2015 and 2016 to investigate the weed control efficacy of five pre-emergence herbicides in cocoyam (NCe012) production. The trial was laid out in a Randomized Complete Block Design (RCBD) with three replications. The treatments consist of Diuron at 3 and 4L/ha, Goal Tender 4F at 0.5 and 0.75kg/ha, Liberator forte at 1.0 and 1.5L/ha, Codal Gold at 3 and 4.5L/ha, Primextra Gold at 3 and 4.5L/ha, three hoe weeding at 4,8 and 12 weeks after planting (WAP) and a weedy check plot. In both years, the plots treated with Goal Tender 4F at 0.75 kg/ha gave the lowest weed dry matter of 6.9 and 7.9 g/m2 at 6WAP, 32.5 and 28.3 g/m2 at 9WAP, while the unweeded check plot had the highest weed dry matter of 20.0 and 24.4g/m2 at 6WAP, 65.7 and 75.0 g/m2 at 9WAP in 2015 and 2016 respectively compared with other treatments. In both years, Goal Tender 4F at 0.75kg/ha was very effective in controlling weed growth at all sampling periods, although the efficacy of the pre-emergence herbicide decreased as the weeks increased after planting (WAP). However its efficacy was still better than other herbicides treatments. Liberator forte at the rate of1.5L/ha was the least effective preemergence herbicide in controlling weeds. Application of Goal Tender 4F at 0.5 and 0.75 kg/ha gave significantly lower crop injury at all sampling periods in both years. For all the period of data collection, it was observed that the unweeded check plot gave the highest weed density in both years, while the plots treated with Goal Tender 4F at 0.75 kg/ha resulted in significantly lower weed density at all sampling periods in both years. For the number of corms and cormels, the results showed that the unweeded check plot gave the least number of corms and cormels. There was a significant difference between the herbicide treatments. Highest corm mean weight of 2.38 t/ha was obtained in plots treated with premextra gold at 4.5 L/ha, while the unweeded check had the lowest mean corm weight of 0.63 t/ha. The results also showed that, Gold Tender 4F at 0.75 kg/ha gave the highest cormel mean weight of 3.95 t/ha, while the least mean cormel weight of 0.38 t/ha were obtained from unweeded check plot. With good weed control, lower crop injury, higher cormel number and weight than other treatments, Goal Tender 4F at 0.75 kg/ha is therefore recommended for weed control in cocoyam in south Eastern Nigeria.
Keywords: Goals tender 4f, Diruon, Codal gold, liberator forte, Weed dry matter, Efficacy, and Crop injury