Adherent Malathion Flour Granules as an Environmentally Selective Control for Chewing Insect Pests of Dent Corn Ears: Indirect Reduction of Mycotoxigenic Ear Molds

Abstract

Reductions of incidence of chewing ear pests produced by application of adherent granular malathion were associated with reductions of mycotoxigenic fungi in each of 4 yr. In a 2-yr comparative study, the incidence of potentially mycotoxigenic Fusarium fungi was significantly reduced by a single hand application of 0.1% (AI) granules at 11 kg granules/ha (0.011 kg/ha [AI]) compared with control plots, and was approximately equal to plots receiving 5 sprays of malathion at 1.1 kg/ha (AI) each. In a 2nd series of studies at this site, the use of 1% malathion granules at 11 kg granules/ha (0.11 kg/ha [AI]) significantly reduced the incidence of chewing corn ear insect pests and visible Fusarium mold in 2 corn hybrids that differed in relative resistance to Fusarium moniliforme Scheld. Different rates of adherent malathion granules were applied with conventional equipment in a small-plot study near Metamora, IL. Because of poor coverage in the ear zone, control of insects and indirect control of Fusarium ear mold was limited. Although year and hybrid effects were involved, there was generally a positive association between insect damage and incidence of mold in the 1994 and 1995 hand-application studies. Relative insect damage at harvest was significantly correlated with fumonisin levels of the hybrids treated in 1995. Thus, in addition to the economic and environmental benefits derived from using granules containing low malathion compared with conventional formulations for insect control described previously, use of these granules also may indirectly reduce ear molds and associated mycotoxins in corn.