1985 Fall Armyworm Symposium: Chemical Control: Fall Armyworm (Lepidoptera: Noctuidae) Control Through Chemigation: An Update
Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larvae can be controlled with insecticides applied as an oil formulation in 2.5-13 mm of irrigation water from an overhead center-pivot irrigation system. When a combination of chlorpyrifos (0.26-0.56 kg AI/ha) and a pyrethroid (permethrin, fenvalerate, or cypermethrin 0.056 kg AI/ha) was chemigated, excellent control of FAW and corn earworm (CEW), Heliothis zea (Boddie), larvae was obtained on spring and summer-grown sweet corn. The best control of FAW and CEW larvae in sweet corn was obtained when the technical insecticide was formulated in an oil and applied on a schedule. Selection of an oil carrier is based primarily on the solubility of the insecticide in the oil and the cost of the oil. Insectigation costs are estimated to be $1.70/10 mm/ha of irrigation water vs. $5.60/ha for conventional applications. Insectigation is used on 2% or 200,000 ha of the available overhead-sprinkler irrigated hectarage in the U.S. Opportunities for expanding the use of this highly efficient and economical technology for applying pesticides are enormous. FAW colonies collected from various areas of the southeastern U.S. were resistant to carbaryl but susceptible to chlorpyrifos. FAW larvae have been collected that are resistant to methomyl but populations generally were still susceptible.