Adherent Malathion Flour Granules as an Environmentally Selective Control for Chewing Insect Pests of Dent Corn Ears: Insect Control

In a small-plot field study, malathion formulated in pregelatinized corn flour as granules at 0.1% was hand applied at a rate of 11.1 kg/ha of granules (0.01l kg [AI]/ha) of granules in 1992 and 1993. Control of Carpophilus lugubris Murray and Helicocerpa zea (Boddie) with a single treatment of the granules was generally equivalent to that seen when a commercial formulation of malathion was applied in 5 sprays at a rate of 1.1 kg (AI)/ha (lib [Al]/acer) per spray. In 1994 and 1995,1% malathion granules at 11.1 kg/ha of granules significantly reduced corn ear insect pests in 2 different corn varieties. No significant effect on coccinellid or Orius spp. numbers was noted compared with untreated plots when the malathion granules were used. Over the top treatments of 0.1-10% granular malathion at 11.1 kg/ha of granules were less effective in controlling ear feeding insects at another site in 1994 compared with the multiple sprays of malathion applied to the ear zone. However, when granules were applied at ear level in 1995, equal or greater control of ear-feeding insects compared with the conventional malathion sprays was noted, depending on the level of active ingredients in the granules. All active ingredients rates of granules had no significant effect on coccinellids compared with untreated plots in 1995, but the conventional malathion sprays killed up to 95% of the coccinellids. When properly applied, these adherent granules should provide acceptable control of many ear-feeding insects in field corn, be more selective toward predators, and use lower levels of active ingredient compared with conventional malathion sprays.