EFFECT OF SORGHUM HYBRID AND IMIDACLOPRID SEED TREATMENT ON INFESTATIONS BY CORN LEAF APHID AND GREENBUG (HOMOPTERA, APHIDIDAE) AND THE SPREAD OF SUGARCANE MOSAIC-VIRUS STRAIN MDMV-B

The effects of sorghum hybrids and imidacloprid seed treatment on infe stations by corn leaf aphids (CLA), Rhopalosiphum maidis Fitch, and gr eenbugs (GB), Schizaphis graminum (Rhondani), and on the spread of sug arcane mosaic virus strain MDMV-B (SCMV) were evaluated in tests at Ha ys, Kansas, in 1993 and 1994. In both years, imidacloprid controlled C LA for 3 to 4 but not for 7 wk after planting. Imidacloprid reduced th e spread of SCMV in a GB-susceptible hybrid (Northrup King S9750) in 1 993 but not in 1994. Differences among hybrids in the incidence of SCM V did not appear to be related to the hybrids' reaction to GB. However , one GB-resistant hybrid (Dekalb DK-39Y) appeared to be highly resist ant to natural infection by SCMV, even though it was susceptible when inoculated mechanically.