Electrostatic ultra-low-volume spraying for the control of cotton boll weevils

The objective of this study was to determine the effectiveness of an electrostatic ultra-low-volume sprayer in controlling the cotton boll weevil (Anthonomous grandis, Boheman). More economical and efficient methods of insecticide application were sought by using variable spray rates, auxiliary air, and electrostatically charged sprays. In the rate study, the full rate (1.25 pounds active ingredient per acre) of Malathion LV Concentrate was the highest in control, the one-half rate was a close second, and the one-fourth rate gave control equivalent to that of the one-half rate in two of the four tests. In the charge and air study, the full-rate charged treatment was superior in control, but the one-half rate charged treatment gave control equivalent to that of the full-rate charged treatment in two of the three tests. The full and one-half rate-charged treatments exhibited an average of 8 percent control greater than the uncharged treatments. The one-half rate uncharged treatment was equal in control to the full rate uncharged without auxiliary air treatment. The row (individual spray nozzle) and date effects were significant in both parts of the study. Row one of the sprayer was highest in control in the rate study. In the charge and air study, row four was found to be superior in control to rows one and two in one of the tests, and row three was superior in control for the other tests. The date effect was found to be significant in the weevil picks tests of both parts of the study. The warmer spray temperatures seemed to increase the overall control obtained, and windy spray conditions (4-10 MPH gusts) did not significantly affect the control obtained. The cage tests of the study were affected by the treatment and data interactions. Generally, the cooler spray dates lowered the performances of the reduced rates the most. The active ingredient rates of insecticide may be reduced up to one-half of the recommended rate and still achieve satisfactory control of the boll weevil. The auxiliary air method was an important factor in the control from reduced rates in this study, and the vise of this method should reduce the amounts and costs of insecticides for cotton.