EVALUATION OF PRE-PLANT-INCORPORATED AND LAY-BY INSECTICIDE APPLICATIONS IN SWEET POTATOES, 2007
J. T. Reed, D. Cook, D. Bao, C. S. Jackson
Arthropod Management Tests
Banded cucumber beetle (BCB): Diabrotica balteata LeConte Spotted cucumber beetle (SCB): Diabrotica undecimpunctata howardi Barber Sugarcane beetle (SB): Eutheola humilis rugiceps (LeConte) Sweetpotato flea beetle (SPFB): Chaetocnema confinis Crotch Systena flea beetle (SFB): Systena spp. White grub (WG): Phyllophaga spp. Wireworm (WW): Elateridae spp. The efficacy of selected pre-plant-incorporated and lay-by insecticides for control of insects damaging sweet potatoes was evaluated at the
... Science North Farm, Mississippi State, MS. Planting date and harvest date were 11 Jun and 7 Oct, respectively. A pre-plant-incorporated (PPI) insecticide was applied in a RCB design on 5 Jun. Prior to hipping, rows within plots were levelled with a do-all followed by an insecticide application applied broadcast at 40 psi and 10 gpa with a spray tractor equipped with a plot sprayer with two Green Leaf 110-01 air injection flat-fan nozzles per row. Replicates were along the rows, and rows were hipped as soon as all plots within a replicate were treated with insecticide. The lay-by application of insecticide to selected plots was applied 19 Jul with the same equipment and settings as the pre-plant incorporated application , but was incorporated into the soil with a rotary cultivator. No other insecticides were applied during the season. Evaluation of damage to the sweet potatoes was made according to the following protocol. Broad, rough, shallow gouges (5-10 mm wide), usually contiguous: WG. Broad, rough, shallow to deep gouges (>10 mm wide), often with separate shallow holes: SB. Pinhole injury: SFB. Small round holes clumped on the potato surface, sometimes with irregular shaped cavities underneath: SCB or BCB. Deep, round holes or with enlarged cavities, usually randomly spaced: WW. Insects in the foliage were sampled six times during the season by taking 25 sweeps along 50 ft in one of the center two rows with a standard sweep net. Data were analyzed with ANOVA, and mean separation was completed with Fisher's LSD (p=0.05). Cochran's C test was used to determine homogeneity of variance. Results of insect damage analysis (Table 1) indicate that all treatments provided significant protection from the WSD complex (damage from wireworms, Systena spp. and Diabrotica spp.), resulting in the untreated plots having significantly more damage than all other plots. However, there were no differences of note between treatments. Brigade 2E (bifenthrin) used as a lay-by application following a PPI application of Lorsban did not increase protection over Lorsban alone. There were no differences between plots for seasonal means of insect numbers (Table 2) .