Control of Twospotted Spider Mites in Peanuts, 1994

Abstract

Abstract This study was conducted to evaluate the efficacy of selected miticides for control of TSSM. One portion of a field was selected because of a uniform infestation of TSSM. The field selected was planted on 36-inch rows on 2 Jun. Management practices were determined by the grower, but did not include any insecticides or miticides. The selected area became heavily infested with TSSM because of lack of moisture from inoperable irrigation nozzles. Each plot was 25 ft long by 2 rows wide. Plots were arranged in a RCBD with four replicates. Treatments were applied on 5 Sep using a CO2 pressurized backpack sprayer calibrated to deliver 20 gpa at 32 psi through one 8004E flat fan nozzle per row. To avoid overspray from adjacent plots, treatments were separated by 2 rows of peanut. Pretreatment counts were taken on 5 Sep just prior to application. Post-treatment counts were made on 13 Sep and 18 Sep, or 8 and 13 DAT, respectively. Treatments were evaluated by comparing mite control on 5 randomly selected plants per plot. Population densities of mites were estimated by sampling an area of 0.35 in2 (2.25 cm2) on each plant in the lower, middle and upper canopy. This sampling scheme resulted in checking 15 leaflets per plot. Yields were determined by digging, combining, drying and weighing peanuts from both rows of each plot. Data were analyzed using ANOVA and LSD procedures.