Celosia argentea L is the most dominating herbaceous annual weed. It grows in all semiarid crop fields like Arachis hypogaea, Cajanus cajan, Dolichos lablab, Phaseolous uterus, Raphanus sativus, Sorghum bicolor, Vigna unguiculata. Allelopathic effects of Celosia argentea L has succeeded in suppressing the yields of cereal crops by promoting the growth of microorganisms. The 1%,2%,3% and 5% of an aqueous root and leaf extracts of Celosia argentea have considerably inhibited the seedling growth of crop plants. So it is recommended that the weed should be physically removed from the crop fields before the allelo chemicals wash down with the rains.