EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003

Abstract

FAW is a serious pest of sweet corn in Florida that normally requires intensive management with insecticides during vegetative and reproductive stages to produce a marketable crop. CEW typically attacks the ears later in the season and frequently requires insecticide treatments in the spring months throughout the state. Euxesta stigmatias larvae attack the corn silk, ears and cob rendering the ears unmarketable. The purpose of this trial was to compare two newer insecticides against standard insecticides for control of the above pests. The trial was conducted at the Everglades Research and Education Center, Belle Glade, FL in a Lauderhill organic soil (i.e., euic, hyperthermic Lithic Medisaprists). Yellow sweet corn seeds (Novartis Seeds ‘GSS 5771’) were planted 20 Aug 2003, 9 inches apart on 30-inch centers using a John Deere Max Merge planter. The study was arranged in a RCB design with four replicates. Plots were 30 ft long, six rows wide, and separated by 5 ft planted, untreated buffers. Blocks were separated on all sides by 15 ft of unplanted buffers. Treatments for naturally occurring FAW were begun once infestation levels reached above a 20% threshold level. Insecticides were applied on 10, 17, 24 Sep, and 1, 8, 14 and 17 Oct using a compressed air spray system mounted on a high clearance spider spray track tractor at 40 psi (nozzle pressure) using 8005 EVS TeeJet nozzles at 15-inch centers across the six-row boom. Insecticides were applied in spray volumes of 30 gpa on the first four dates and 55 gpa on the last three dates. Induce spray adjuvant was added at 0.25% v/v to all treatments, including the water check. Pretreatment (8 Sep) and post treatment samples to evaluate the treatments consisted of examining 10 randomly selected plants in each of the center three rows in each plot (30 plants per treatment replicate) for live FAW larvae. Thirty ears per treatment plot were harvested on 20 Oct and examined for FAW, CEW and E. stigmatias damage. Data were subjected to ANOVA and means were separated using LSD (P ≤ 0.05).