A weed survey conducted to determine the incidence of Parthenium hysterophorous l. (f) in vegetable crops during the wet and dry seasons in Trinidad indicated that the plant is a predominant noxious weed. It has shown the ability to survive bipyridylium herbicide treatments, and biological and cultural control was insignificant in reducing the population of the weed. The weed reduced crop yield in tomato (lycopersicon esculentum Mill.) cv, Calypso by 10~ and crop quality in Cauliflower (Brassica aleracea var. botrytis l.j by 75-100% due to its competitive ability and allelopathic potential. The plant served as a suitable 'resting site' for the adult insect pest Plutella xylostella (l.) (Lepidoptera: Yponomenitidae) which attacks cruciferous crops.