Evaluation of Foliar Insecticide Applications for Grasshopper Control in Cotton, 2016* Open Access

This test was conducted in a commercial cotton field near Plainview, TX. The field was planted on 4 Jun on 40-inch row spacing. The field was irrigated using a drip irrigation system. The experiment was designed as an RCB with six treatments and four replications. The plots were 4-row wide × 40 ft. in length. Treatments were applied on 12 Aug. Insecticide applications were made with a CO₂ pressurized hand-boom sprayer calibrated to deliver 10 gpa through hollow cone TeeJet TXVS6 spray tip nozzles (two per row) at 30 psi. Wind speed was well below 10 mph during spray applications. Insect sampling was done by swinging the sweep net through the top of the canopy. Each sample consisted of DG nymphs and adults collected in 25 consecutive sweeps taken in a row while walking forward. Sweep net contents (foliage + insects) were placed in plastic ziplock bags and brought to the laboratory. Plastic bags containing insects were stored at 3°C for further processing. Laboratory processing included counting of DG nymphs and adults found per sample. Sampling was conducted at 3, 7, and 21 DAT. Data were analyzed by ANOVA, and means were separated by LSD.

There were no significant differences among treatments for numbers of DG adults at 3, 7, or 21 DAT or for numbers of DG nymphs and total grasshoppers at 21 DAT (Table 1). At 3 DAT, only Baythroid XL and Prevathon resulted in significantly fewer DG nymphs compared to the untreated check, while all of the insecticide treatments resulted in significantly fewer total grasshoppers than the untreated check. At 7 DAT, all of the insecticide treatments resulted in significantly lower numbers of DG nymphs and total numbers of grasshoppers compared to the untreated check. Also, plots treated with Baythroid XL, Hero, or Prevathon had significantly lower densities of total grasshoppers than plots treated with Lorsban.

Author notes