STUDIES ON WEED INTERFERENCE AND CONTROL IN COTTON (Gossypium hirsutum L.)/COWPEA (unquiculata L. (Walp.)] MIXTURE AT SAMARU, NIGERIA

STUDIES ON WEED INTERFERENCE AND CONTROL IN COTTON (Gossypium hirsutum L.)/COWPEA (unquiculata L. (Walp.)] MIXTURE AT SAMARU, NIGERIA

Abstract:

Field experiments were conducted during the 1987, 1988 and 1989 cropping seasons on the farm of the Institute for Agricultural Research, Samaru (11°, 111N; 07° 381E) , to evaluate the effects of period of weed-interference and weed control on the performance; of 3:1 replacement population cotton/cowpea mixture. The losses caused by weed-infestation throughout the life cycle of the crops in the three seasons were averaged at 96.2% for seed cotton and 90.1% for cowpea grain yields, compared with those kept weed-free throughout. Weed-infestation throughout the crop life cycle also reduced the yield components, namely flower and boll counts of cotton, by 85 to 94.8%, pod count of cowpea by about 80.4%, as well as dry matter of cotton and cowpea crops by about 78.2% and 82.0%, respectively. Regression of cotton/cowpea mixture’s yields on weed dry matter indicated that, every 1 kg increase in weed weight, reduced seed cotton and cowpea grain yields by 0.19 kg/ha and 0.2kg/ha, respectively. The critical period of weed competition in cotton/cowpea mixture was between 3 and 6 weeks after sowing cotton (WASC) using cotton as top canopy crop grown in the traditional “Gicci” system. The most effective herbicide treatment in this mixture was alachlor plus diuron at 1.0 + 0.4 kg a.i./ha followed by (fb) supplementary hoe-weeding (SHW) at 6 WASC, which out-yielded two hoe-weedings by 9.1% and the weedy check by 90.3% in terms of seed cotton yield. This treatment, however, resulted in seed cctton yield that was 13% lower than that of three hoe-weedings. In component cowpea, alachlor plus diuron at 1.0 + 0.4 kg a.i./ha fb SHW gave grain yield that was higher than those of two and three hoe-weedings,and the weedy check by 27.5%, 16.2% and 80.6%, respectively. Revenue realised in excess of chemical weed control cost was N7,685/ha, compared with N6,215.00 for three hoe-weedings, and N5,495.00, for two hoe-weedings.

STUDIES ON WEED INTERFERENCE AND CONTROL IN COTTON (Gossypium hirsutum L.)/COWPEA (unquiculata L. (Walp.)] MIXTURE AT SAMARU, NIGERIA