ASSESSMENT OF IRRIGATION-RELATED INSECTICIDE APPLICATION METHODS FOR CONTROL OF LEPIDOPTERAN INSECT PESTS OF SWEET CORN

Application of insecticides through center-pivot irrigation systems du ring the spring and summer growing seasons of 1990 and 1991 was as eff icient in controlling com earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae in fresh-market com, Zea mays (L.), as was the application of insecticides with a high -clearance sprayer. Hollow cone and rotating irrigation sprinklers app lied insecticides uniformly along the length of the pivot arm, resulti ng in less-than-or-equal-to 3% com ear damage in all growing seasons. Insect damage to ears following use of insecticides applied with a pig gyback application system and a high-clearance sprayer was similar and generally above the acceptable range (less-than-or-equal-to 3% damage d ears) for fresh-market use in most growing seasons. Insecticides app lied with the piggyback system failed to provide uniform insect contro l along the irrigation pivot arm in both 1990 and 1991.