Main Article Content
An investigation was made for two consecutive seasons (2000 and 2001) to determinethe critical period of weed competition and yield and quality loss of cotton(Gossypium hirsutum L.) in the Middle Awash, Ethiopia. The experiment wasconducted at two sites viz. research field of Werer Agricultural Research Center andWerer Cotton State Farm. Quantitative series of both increasing duration of weedyand weed free periods were compared with complete weed free and weedy check.Treatments were arranged in RCBD with three replications. Data was collected onyield and yield components and lint quality parameters. At both locations, the meanyields of weed-infested treatments showed a decline as the weed infestation periodincreased and vice versa as the weed free period increased. Yield loss of 62-96%occurred when weeding was completely denied. The study indicated that the criticalperiod of weed competition in cotton in the Middle Awash was early to mediumgrowth stage of the cotton plant, i.e. 20-60 days after crop emergence. This indicatesthat the weed management practice should focus on this stage to suppress weedcompetition and achieve optimum yield. Weeds which emerge after the criticalperiod still need to be controlled to avoid harvesting difficulties and lintcontamination and should not be allowed to set seed, as this will lead to increasedweed problems in later seasons. With regard to quality parameters of cotton lint, aone-year data (2000) showed a significant difference (p≤0.05) for micronaire valueand fiber maturity percent.