Insecticide Evaluation for Grasshopper Control in Bermudagrass Pasture, 2015*

Selected insecticides were evaluated for control of a mixed population of second and third instar Melanoplus spp. grasshoppers on bermudagrass pasture at the Wes Watkins Research and Extension Center in Lane, OK in 2015. Plots measuring 20 × 30 ft were established and treatments arranged in a RCB design with four replications. Plots were sprayed on 24 Jun, with a CO₂-charged bicycle sprayer with a 12.5 ft boom and 18-inch nozzle spacing through 8002 flat fan nozzles at 20 psi for a total volume of 20 gpa. Plots were allowed to dry, and then a plastic cage measuring 1 m² × 30 cm h and covered with fine mesh netting was installed in each plot. Ten live second and third instar grasshoppers were collected from an untreated area of the pasture and placed in each cage after the application. Efficacy was evaluated using two methods: (1) counting live grasshoppers captured with a sweep net taking 15 sweeps/plot, and (2) counting live grasshoppers in each cage. Post treatment counts were taken on 27 Jun (3 DAT), 1 Jul (7 DAT), and 8 Jul (14 DAT). All data were analyzed using ANOVA and differences among treatments were determined using Fisher’s Protected LSD (P < 0.05).

Many spiders were present in cages and in the field 3 DAT and 7 DAT. All treatments significantly reduced grasshopper numbers 3 DAT and 7 DAT with sweep net and cage evaluations. Grasshoppers began to move back into treated plots at 14 DAT; however, the treated cages had significantly lower than the check. None of the chemicals maintained significant control of grasshoppers at 14 DAT (Table 1).

Author notes