ABSTRACT

Increased Costs of Insect and Disease Control Weeds serve as alternative hosts to several crop insects, nematodes and pathogens. Insects such as aphids, thrips, weevils and stem flies survive on Brassica kaber (wi ld mustard), Daucus carota (wi ld carrot), Ambrosia spp. (ragweed), Amaranthus retroflexus (redroot pigweed), etc. Weeds such as Avena fatua (wi ld oats) and some perennial grasses harbour pathogens of black stem rust of wheat. By harbouring these insects and pathogens, their attack on crop plants is increased. This results in increased cost of their control.