Assessment of weed management strategies on cassava (Manihot esculenta Crantz) growth and yield in Ghana.

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A field experiment was conducted at the Kwame Nkrumah University of Science and Technology Kumasi, Ghana, between May, 2014 and May 2015 cropping season to assess weed management strategies on cassava (Manihot esculenta Crantz) growth and yield. The experiment was set up as a 6 x 2 factorial arranged in a randomized complete block design replicated four times. The treatments consisted of two cassava varieties- Ampong (Early branching) and Dokuduade (late branching). Six weed control methods studied were: application of Butachlor at 4l/ha + 2 hoe-weedings, Terbulor at 4l/ha + 2 hoe-weedings, three-time manual hoe-weedings, three-time manual cutlass-weedings, weed-free and weedy checks treatment. The predominant weed species were Tridax procumbens, Mimosa pudica, Euphorbia heterophylla, Croton hirtus, Spigelia anthelmia, Digitaria ciliaris, Centrosema pubescens, Brachiaria deflexa and Panicum maximum consisting 85% weed density in the field. Ampong variety was superior in growth and yielded greater than Dokuduade variety on an average of 9.65 and 8.49 respectively. Hoe weeding was more effective than cutlass weeding in controlling weeds under cassava. Among the weeding treatments studied, Terbulor at 4l/ha + 2 hoe-weedings had significantly maximum effective weed control which resulted in over 91% tuber root yield. Additionally, the Terbulor at 4l/ha + 2 hoe-weeding had significantly higher net revenue (6,899.18 GH¢/ha) than weed-free (5,735.97 GH¢/ha) and weedy (1,807.85 GH¢/ha). Thus, the application of Terbulor at 4l/ha + 2 hoe-weeding seemed most appropriate for weed control in cassava fields.
A thesis submitted to the Department of Crop and Soil Sciences, Faculty of Agriculture KNUST, Kumasi in partial fulfilment of the requirement for the award of Master of Philosophy in Agronomy (Weed Science), 2015