Effects of integrated weed management on tuber yield of cassava (Manihot esculenta Crantz)

Field experiments were conducted in 2012 and 2013 at the Teaching and Research Farm of the University of Calabar, Cross River State, Nigeria to determine the effectiveness of integration of Fitsextra® (a solution containing Atrazine and Metolachlor herbicides as active ingredients), egusi melon and hand-weeding on weed management and tuber yield of cassava. The twelve treatments which involved individual and combinations of the above mentioned weed control methods were laid out in a randomized complete block design and replicated three times. Irrespective of the method adopted, weeding depressed weed density by 57.33 % and 63.99 % in 2012 and 2013, respectively and weed biomass by 81.00 % and 79.64 % within the same period compared with the unweeded check. Integration of Fitsextra with egusi melon and/or hand-weeding significantly (P<0.05) suppressed weeds more than the sole use of Fitsextra® or egusi melon. Integration of hand-weeding with Fitsextra and/or egusi melon reduced weed dry matter by 43.46, 87.25, 92.34 and 93.51 % in 2012, and by 53.20, 90.20, 94.61 and 94.56 % in 2013 compared with hand-weeding alone, Fitsextra alone, egusi melon alone and no weeding, respectively. Plots that were hand-weeded thrice and those treated with Fitsextra + hand-weeding twice significantly (P<0.05) produced the highest fresh tuber yield of 9.73 and 10.23 t/ha, respectively in 2013. No weeding reduced cassava tuber yield by 4.83 t/ha (84.89 %) on a 2-year average, compared with the weeded plots. Conclusively, the results indicated that, three hand-weeding optimized cassava tuber yield, however, the integration of Fitsextra or egusi melon can effectively replace the first hand-weeding.