EFFECTS OF PERIOD OF WEED INTERFERENCE AND CHEMICAL WEED CONTROL ON POT^TO (Solanum tuberosum L.)

EFFECTS OF PERIOD OF WEED INTERFERENCE AND CHEMICAL WEED CONTROL ON POT^TO (Solanum tuberosum L.)

Abstract:

Two field experiments were conducted during the 1985 wet season at Samaru in the northern Guinea savanna ecological zone of Nigeria to study the effect of period of weed interference one evaluate herbicide mixtures for weed control in Irish potato (Solanum tuberosum L.). The potato varieties B7906-I and Greta were most critically affected by weed interference between 3 and 6 weeks after planting (/AT) and. 6 and 9 weeks after planting (WAP), respectively. Weed infestation for the first 3 weeks after planting did not have any adverse effect on the two potato varieties. However, once infested by weeds until 9 W.AI , subsequent weed removal did not obviate the loss in yield, caused by weed competition with the variety Greta. Keeping B.7906-I and Greta weed-free until 6 and 9 WAP, respectively resulted in yields comparable to the appropriate weed-free controls. It was required to keep variety Greta weed-free throughout its life-cycle and B7906-I weed-free until 50 days after planting in order to obtain maximum tuber yields. As reflected in yields of the crop kept weed-free initially for various periods and those infested for 3 WAP only, it was apparent that with adequate weed central, Greta had higher tuber yield potential than B7906-I. Among the herbicide mixtures tested on Greta, metolachlor plus metribuzin at 1.00 + 0.25 kg a.i./ha, mixtures of metolachlor with metabromuron and prometryne each at 1.00 + 1.00 and 1.30 + 1.50 kg a.i./ha and ametryne at 1.50 + 1.00 kg a.i./ha combined season-long weed control with high tuber yields, soluble carbohydrate and crude protein that were comparable to those of two and three hoe-weedings. In the study, weed association with the crop throughout its life-cycle adversely depressed crop vigour, leaf area, leaf area index, tuber soluble carbohydrate end crude protein contents and caused crop yield reduction by about 71.O% And 63.8%, in weed interference and chemical weed control experiments, respectively compared with the appropriate best treatments.

EFFECTS OF PERIOD OF WEED INTERFERENCE AND CHEMICAL WEED CONTROL ON POT^TO (Solanum tuberosum L.)