Planting Time Treatments for Greenbug (Biotype E) Control on Grain Sorghum, 1985

This test was conducted at the University of Nebraska Field Laboratory, Mead, NE, in grain sorghum planted 24 May in Sharpsburg silty clay loam (Typic Argiudoll). The experimental design for this test was a randomized complete block with 6 replications. Insecticides were applied as single-row treatments, 22 ft long and 30 inches between rows. In-furrow treatments were applied with the seed by using a seed cone mounted on a 1-row John Deere 71 Flexi-Planter. Banded treatments were applied by a V-belt applicator with a 4-inch spreader directed over the seed row. Incorporation was with a tine rake. Soil temperature at planting time was 74°F (2-inch depth). Rainfall from initial planting date to the last greenbug sampling date was measurable in inches 27 May (0.50), 29 May (0.40), 4 Jun (0.50), 11 Jun (0.70), 19 Jun (0.25), 21 Jun (0.25), 23 Jun (0.40), 26 Jun (0.80), 18 Jul (0.20), 19 Jul (2.35), and 24 Jul (0.50). The efficacy of each insecticide was evaluated by counting live greenbugs on each of 6 plants selected at random from each row at weekly or semi-weekly intervals. Greenbug counts were continued until populations had a high number of parasitized mummies (29 Jul). Dead leaf counts were made 16 Sep by evaluating 10 plants selected at random in each replication for greenbug-caused necrosis.