Insecticide Evaluations Against Soil Insect Pests of Blueberries, 1994

Abstract

This experiment was conducted in a nonbearing 3-year-old ‘bluecrop’ blueberry field, near Hammonton, NJ. Soils at this location were sandy loam with 4.7 pH and irrigated season long. Blueberry bushes were approximately 3-4 ft tall and spaced 3 × 8 ft apart. Treatments were replicated 6 times in a randomized complete block design with each replicate consisting of 48-ft-long rows with 10-12 bushes in 2 to 4 rows. Treatments were separated by at least 2 unsprayed rows and 4 unsprayed plants within a row that served as buffer. Insecticides were applied as a 1-ft band on both sides of the plant for a total of 96 sq ft of treated area per replication. Granular insecticides were applied by spreading the granules evenly by hand and incorporated to a depth of 1-2 inches using a hand hoe. Liquid formulations were applied with a CO2 pressurized Model T backpack sprayer (R&D Sprayers) equipped with a single TeeJet nozzle (8002VS) operated at 35 psi. Insecticides were applied twice, on 3 Jun and 24 Aug. Insecticides were sprayed using 1.5 liters of water per replicate on 3 Jun and 1 liter on 24 Aug (30—45 gal/acre). Following each application the field was irrigated by drip irrigation with at least 1 inch of water. Treatment effects were evaluated by examining soil and roots in 1-ft-diameter by 1-ft deep areas around the plants (2 plants/replicate) for whitegrubs (including OB, JB, AGB) and mealybugs. Colonies of newly hatched nymphs of mealybugs were counted separately. Plants were sampled between 20-27 Jun following the first application and between 12-19 Sep following the second application.