Abstract

eeds are different from the other pests that pose problems in crop production because the presence of weeds is relatively constant, while outbreaks of insects and disease pathogens are sporadic (Gianessi and Sankula, 2003). 1,800 weeds species cause serious economic losses in crop production, and about 300 species plague cultivated crops throughout the world (Ware and Whitacre, 2004). Weeds are the scarce and silent robbers of plant nutrients, soil moisture, solar energy and also occupy the space which would otherwise be available to the main crop; harbour insect-pests and disease causing organisms; exert adverse allelopathic effects; reduce quality of farm produce and increase cost of production.