The experiment was conducted at Gia'r experimental farm, Al-Kod Agricultural Research Station during 98/1999 and 99/2000 seasons, using long-staple Cotton variety "KB-138", to study effect of weed control, weed density and weed competition with Cotton plants, especially at early stages of Cotton growth till flowering. Complete Randomized Block Design was used with 4 replications and 8 treatments of manual, mechanical and combined weeding methods with varying number of times and periods from planting date, including a control treatment. Mechanical weed control was done with MF-567 machine. Results showed significant differences between treatments in both seasons. Manual and mechanical weeding treatment were better than the control. Cotton yield increased more number of weedings. Treatment of 3 manual weedings till 60 days after planting and that of continuous weed control, gave best Cotton yield and least weed density. Broad-leaf weeds, specially Solanum dubium, were more than narrow-leaf weeds with high density Cynodon dactylon.

Key Words :Weeds, Cotton, weed control.