THE INFLUENCE OF WEEDS ON INSECT-RELATED MORTALITY OF INTERCROPPED SORGHUM AND MAIZE IN SOUTHERN HONDURAS

Partial crop life tables were constructed during 1988 and 1989 to dete rmine plant mortality factors in intercropped sorghum and maize in sou thern Honduras. Whole plant samples of sorghum and maize were taken fr om plots without weed control and those with weed control. Seed viabil ity, wireworms, and cutworms were the most important factors in stand establishment. Other insects like Listronotus dietrichi (Stockton) and Diatraea spp. played a minor role in plant mortality and were habitat specific. Once plant stands were established, insects had little effe ct on reducing plant densities; however, a mid-season drought signific antly reduced maize stands; the presence of weeds exacerbated the effe ct of drought on maize. Sorghum, which was still in its vegetative pha se, was not affected by drought. An enhanced maicillo cultivar with an tibiosis to fall army worm suffered significantly less cutworm damage than maize. The results indicate that good sorghum stands could be est ablished in normal rainfall conditions by deployment of enhanced culti vars with good seed viability and insect resistance.