Assessing planting date, biological control, and host plant resistance for management of corn leaf aphid

Abstract

The corn leaf aphid, Rhopalosiphum maidis, is an important pest of fresh market sweet corn in New York. Heavy infestations can reduce yield and adversely affect ear quality by direct or indirect (sooty mold) contamination. Corn leaf aphids also transmit maize dwarf mosaic and barley yellow dwarf virus. Over the past few years there have been reports of problems with corn leaf aphid infestations and of poor control with available insecticides. Biological control is one of the fundamental components of IPM and offer good prospects for the suppression of corn leaf aphid populations in a sweet corn system. To improve the management of this pest we assessed corn leaf aphid infestations and the associated natural enemy complex in early-, mid-, and late- season plantings of sweet corn. We recorded relatively large numbers of natural enemies, but it was insufficient to keep aphid numbers below action thresholds. Coccinellid counts from yellow sticky cards were not good indicators of coccinellid numbers on corn plants. An evaluation of corn breeding lines indicated that lines resistant to European corn borer may possess resistance to corn leaf aphids.