Evaluation of Warrior Against the Corn Thrips, 1996

Corn thrips is an important pest of the corn seed industry in Hawaii. If the insect is not controlled, it causes direct feeding injury that results in plant stunting or death of young corn plants. At these injury levels, economic reductions in seed yield of 70 to 100% have occurred. The field evaluation was conducted at Pioneer Hi-Bred International’s field located near Kekaha on the Hawaiian island of Kauai. Two rates of Warrior (1 EC), a treated standard (Capture 2 EC at 0.1 lb (AI)/acre) and an untreated check, were set in a RCB design with four replications. Each treatment replicate consisted of 10 rows of corn at 30 ft. length. The field was seeded on 18 Mar on 30 inch centers and 8.5 inch in-row plant spacing. Treatments were separated by a 5-ft non-spray buffer area. Adjacent replications were separated by a 10 ft non-spray buffer area. Total area used for the test was approximately 0.22 acre. Sprays were applied with a John Deere 6500 sprayer at 33 psi with an output of 40 gpa. The boom was equipped with two twin jet 8004 nozzles per row, one directly over and one between each row. Treatment applications were initiated four weeks after planting the field when the plants were in the 4-5 leaf stage. Treatments were made on 11 and 18 Apr. Whole plant samples were taken four times during each field trial. On each evaluation date, 10 plants from each treatment replication were randomly selected using a zigzag pattern. Each plant was cut near the base and placed in separate plastic bags. Pre-treatment samples were taken 1 day before the first chemical application. Post-treatment evaluations were made 5 days and 7 days after the first spray application. Subsequently, the fourth evaluation was made 5 days after the second spray application.