PLANTING DATE AFFECTS TROPICAL SPIDERWORT (COMMELINA BENGHALENSIS)-FREE INTERVAL IN COTTON

摘要

A study was developed to test our hypothesis that cotton planting date can affect the competitive balance between cotton and spiderwort. To evaluate the effect of the duration of spiderwort interference, two companion studies were conducted. The firststudy was designed to evaluate the effect of duration of weed competition from the beginning of the season lasting for 2, 4, 6, 8, and 10 weeks. After this interval, the spiderwort plants were removed through a combination of cultivation and hand hoeing. This study will tell us how long cotton can tolerate interference from spiderwort before they begin to compete for the same resources. This will help to quantify when control programs need to be initiated. The second study was designed to evaluate theeffect of late-season spiderwort emergence on cotton yield. Plots were kept free of spiderwort for intervals of 2, 4, 6, 8, and 10 weeks after cotton emergence, after which spiderwort was allowed to reinfest the plots. There is a point in the growing season at which cotton will have enough of a head start that late emerging weeds will not have a significant influence on cotton growth and yield. Included in these studies were a weed-free control and a weedy-control. When combined, the results of this study will provide us an interval of when postemergence weed control needs to be initiated and the length of soil residual control that will be required.