Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/1998
Publication Date: N/A
Interpretive Summary: Insects cause hundreds of millions of dollars of direct losses to corn each year. The ear damage they cause also increases problems with fungal toxins, which can result in up to a billion dollars of associated losses each year. The number of applications of conventional formulations of insecticides required to control ear feeding insects at sufficient levels is not economically realistic. These insecticides can also disrupt natural controls and cause residue problems. A new formulation was used that requires less insecticide per acre, does not harm natural controls, and causes no detectible residues. When properly applied, it controlled ear feeding insects as well as conventional formulations. Incidence of molds that produce fungal toxins was reduced and corresponded to reduction in insect damage. Corresponding reductions in mold toxins also occurred in some years. This formulation has potential for solving several problems with corn damage in an environmentally friendly manner.
Technical Abstract: In a 2-year comparative study, the incidence of potentially mycotoxigenic Fusarium fungi was significantly reduced by hand application of 0.1% a.i. malathion granules (at 11 kg granules/ha) compared with control plots and was approximately equal to plots receiving five sprays of malathion at 1.1 kg/ha a.i. each. In a second series of studies at this site, use of 1% malathion granules at 11 kg granules/ha significantly reduced corn ear insect pests and visible Fusarium mold incidence in both of two corn varieties that differed in relative resistance to Fusarium moniliforme Scheld. Multiple dose ranges of formulated technical malathion were applied with conventional equipment in a small plot study near Metamora, IL. Due to poor coverage in the ear zone, the adherent malathion granules controlled insects and indirectly controlled Fusarium ear mold to a limited extent. There was generally a positive association between insect damage and incidence of mold in the 1994 and 1995 hand application studies. Significant insect control was associated with up to a 5-fold reduction in overall fumonisin levels of the F. moniliforme susceptible hybrid treated with granules by hand in 1995. Thus, in addition to the economic and environmental benefits derived from using the low a.i. malathion encapsulating granules compared to conventional formulations for insect control described previously, use of these granules may also indirectly reduce mycotoxins in corn.