Aphid Control on Blueberries, 2019

This experiment tested the efficacy of five insecticides for controlling aphids in highbush blueberries. The insecticide treatments and rates were Assail 30SG at 5.3 oz/ac, Beleaf 50SG at 4.3 oz/ac, Exirel 10SE at 13.5 and 20 floz/ac (+ Dynamic 0.25% v:v), Movento 240SC at 10 floz/ac (+ Dynamic 0.5% v:v), Sivanto at 4.3 floz/ac, and an untreated control. The experiment was conducted in a mid-season blueberry field, cv. ‘Bluecrop,’ located at the P.E. Marucci Blueberry/Cranberry Center in Chatsworth, New Jersey. Plots consisted of single bushes, with treatments repeated on six plots in a CRB design and separated by at least two buffer bushes and a buffer row. Control bushes received no insecticides. Applications were made with an R&D CO₂ backpack sprayer, using 2 liter plastic bottles. The sprayer was calibrated to deliver 40 gal of volume per acre at 30 psi, using a single ConeJet TXVS 10 nozzle, yielding 125.1 ml (4.23 fl oz) per bush. Treatments were applied on 7 June.

Aphid-infested terminals were collected on 3 June from a commercial blueberry farm in Hammonton, New Jersey, inserted in florists’ water picks secured on plastic shoeboxes, and enclosed in ventilated 40-dram plastic vials. Terminals were maintained in the lab for 3 days before used in experiments. Two days prior to treatment, an undamaged terminal (20–30 cm long with 5–7 leaves attached) was selected on each bush and enclosed in a gauze bag (Temkin International; Springville, UT, USA). After bags were in place, one adult aphid and nine nymphs were placed on each terminal and the bags were sealed. Aphids were given 36 h to settle on the foliage before treatments were applied. On 7 June, each bag was opened and the foliage was sprayed and allowed to dry for 30 min before being re-sealed. There were six terminals for each treatment, with each terminal considered a replicate. Aphid numbers on the bagged terminals were evaluated four days after treatment on 11 June. There was 2.72 cm (1.07 inches) of precipitation after the treatment and before terminals were removed from the field for evaluation.

For evaluation, each bagged terminal was clipped and inserted in a florists’ water pick, then brought back to the lab for evaluation under 3× magnification using a headband lens (OptiVISOR, Donegan Optical Co.; Lenexa, KS, USA). The number of live nymph and adult aphids was recorded separately and used to calculate total live aphids and percent control. Percent control was calculated for each treatment as [1 − (avg. aphids on treated foliage/avg. aphids on control foliage)] × 100. Data were analyzed using ANOVA and means separation by Fisher’s tests at α = 0.05. Count data were ln(x + 0.1)-transformed prior to analysis.

Assail, Movento, and Sivanto reduced the number of aphid nymphs by ≥95% (Table 1). Beleaf and Exirel reduced the number of nymphs by 70–85% compared to control (Table 1). Assail and Sivanto reduced the number of adult aphids by >95% (Table 2). Movento, Beleaf, and Exirel at the high rate also reduced the number of adult aphids by 70–90% compared with control (Table 2). No phytoxicity symptoms were observed following any of the insecticide treatments.²

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