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Blueberry Aphid Bioassay on Blueberry, 2008

L. K. Tanigoshi, B. S. Gerdeman and G. Hollis Spitler
Washington State University
Mount Vernon Northwestern Research and Extension Center
Mount Vernon, WA 98273-4768

Blueberry aphid, Ericaphis fimbriata (Richards).

Blueberry aphids on a blueberry leaf.Blueberry aphids on the underside of a blueberry leaf.A population of alate blueberry aphids was collected on 17 July from a varietal blueberry planting at the WSU Mount Vernon NWREC. Terminal leaves were individually, placed top-side-up, between 3.5″ × 7.5″ cotton absorbent/lint-free pads.The pads were folded in half with the top half containing a 1.2″ diameter circle formed from a cork punch. This unit was placed in a 5″ diameter plastic Petri dish and saturated with water to form a water barrier around the arena. Between 10-13 wingless, blueberry aphids were carefully placed in the arena with a 00 camel hair brush and allowed to settle before topically treated to wetting with a hand held atomizer with the aphicides listed below. These arenas were held under laboratory conditions. Compared with the untreated check, all treatments were significantly different at the 5% level through 11 days posttreatment (Table 1). Both rates of Assail 70WP provided quick knock-down of blueberry aphid within 24 hours of their exposure. Experimental Movento™ (spirotetramat) “2-way systemicity” and unique mode of action via ingestion provided complete population mortality by 8 DAT for both rates tested. Movento has been shown to provide excellent residual out to 21 DAT. Movento must be applied as aphid population begins to increase because it is not curative. Experimental Cyazypyr (DPX-HGW86) has a ryanodine receptor activator mode of action, is translaminar via foliar application, is systemic via root uptake and induces cessation of feeding when ingested. The latter symptom was observed with two formulations and four treatments after 1 DAT, though complete population mortality was delayed to or through 11 DAT.

Table 1. Blueberry aphid leaf bioassay on blueberry, 2008.
Treatment Rate/acre Percent Mortality(1)
1 DAT 3 DAT 5 DAT 8 DAT 11 DAT
Mean within columns followed by the same letter are not significantly different (Fisher’s protected LSD, P<0.05), PRC ANOVA SAS.
MSO = methylated seed oil adjuvant; SE, suspo emulsion; OD, oil dispersion.
*Buffered to a pH of 5 or lower.
(1) Live females may produce progeny between sampling periods <% mortality over time.
HGW86 10SE* 13.6 fl oz 32b 24cd1 77abc 91a 97a
HGW86 10SE* 20.6 fl oz 3c 27cd 55c 67b 74b
HGW86 10SE* + MSO 13.5 fl oz 23bc 40cb 71bc 87a 100a
HGW86 OD* 13.5 fl oz 10bc 42cb 74abc 90a 91ab
Assail 70WP 1 oz 100a
Assail 70WP 2.3 oz 100a
Movento 240SC + Dyne-Amic 5 fl oz 22bc 61b 84ab 100a
Movento 240SC + Dyne-Amic 8 fl oz 8bc 39cb 81abc 100a
Untreated check 0c 3d 3d 4c 20c