Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2000
Publication Date: 10/1/2000
Citation: DOWD, P.F., PINGEL, R.L., RUHL, D., SHASHA, B.S., BEHLE, R.W., PENLAND, D.R., MCGUIRE, M.R., FARON, E.J. MULTIACREAGE EVALUATION OF AERIALLY APPLIED ADHERENT MALATHION GRANULES FOR SELECTIVE INSECT CONTROL AND INDIRECT REDUCTION OF MYCOTOXIGENIC FUNGI IN SPECIALTY CORN. JOURNAL OF ECONOMIC ENTOMOLOGY. 2000. v. 93(5). p. 1424-1428. Interpretive Summary: Corn insect damage causes multimillion dollars of losses to corn each year. Insect damage to corn ears also promotes the establishment of toxin-producing ear molds. The presence of these toxins is a serious health threat to people and animals, and also makes U.S. corn less competitive on the international market. An aerially applied adherent granular corn flour formulation of malathion that has very low levels of the active ingredient was generally found to control ear-damaging insects, as well as a commercial granular formulation of a more toxic insecticide, without harming beneficial insects. Visible ear molds were also as low or lower in the malathion granule treated ears compared to the ears treated with the commercial insecticide. In contrast to the commercial granular formulation, the malathion granules did not dislodge onto skin or clothes during scouting. The adherent granular formulation is an effective, yet safer formulation of potential use for controlling insect ear pests and associated toxin-producing ear molds. Use of this formulation should also decrease input costs to growers and increase overall acceptability of the product due to lower pesticide and mold toxin presence.
Technical Abstract: Aerially applied adherent corn flour granules containing 1% malathion were often as or more effective than 15% chlorpyrifos (Lorsban 15G*) granules in controlling chewing insect ear pests of high-amylose corn. Use of malathion granules corresponding closely in size to chlorpyrifos granules in the second year of the study apparently increased relative efficacy. Control of corn borer damage on plants (1996) or ears (1997) within two weeks of application was equal or greater by the malathion granules compared with the chlorpyrifos granules. In 1997, six- fold fewer ears had greater than 20 kernels damaged per ear for the malathion vs. chlorpyrifos treatments. Control of beetles (corn rootworm adults and sap beetles) for both treatments was less effective compared to caterpillars, but significant sap beetle control was noted for the malathion granules in 1997. Significantly fewer live lady beetles and more dead lady beetles were present in chlorpyrifos-treated plots compared with malathion-treated or untreated plots in 1996. The incidence and severity of Fusarium mold on ears was reduced more by malathion treatments than chlorpyrifos treatments in both 1996 and 1997.