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Evaluation of Novel Insecticides for the Rationale Control of Aphids in Strawberries – 2002

L. K. Tanigoshi and J. R. Bergen
Washington State University
Vancouver Research and Extension Unit
Vancouver, WA 98665-9752,

A greenhouse infestation of strawberry aphid, Chaetosiphon fragaefolii, on ‘Totem’ strawberries was sprayed with several experimental aphicides. Those were Actara® (thiomethoxam), Admire® (imidacloprid), Assail® (acetamiprid), and Fulfill® (pymetrozine). Individual potted plants were arranged in a randomized complete block design replicated ten times with 6 treatments. These were applied with a Solo® backpack pressure sprayer at 40 psi with a 5500 adjustable conejet nozzle. Our recommended aphicides for strawberry aphids for the PNW include three older OP compounds that are currently at risk for cancellations in the near future. Samples consisted of three randomly picked leaflets per plant and replicated six times.

The neonicotinoids, Actara, Admire and Assail are all designated as OP alternatives with Assail receiving the additional label of reduced risk pesticide by EPA/FQPA. Fulfill is a novel biorationale that has demonstrated excellent efficacy against a broad range of aphid species. Its mode of action affects aphid feeding shortly after exposure, resulting in mortality due to starvation after 2-5 days. This compound is slower acting than the nervous system disrupter malathion and the three experimental neonicotinoids. Compared with the untreated checks, the average nymphs and adults per leaflet for the five aphicides tested were significantly different at the 5% level after 1, 3, 6 and 10 days posttreatment (Table 1). The older malathion and the soon to be registered Admire provided rapid knockdown of all instars of the strawberry aphid after 24 hours. The widely used cereal grain application of Admire provides systemic control of cereal aphids up to 70 days. After 3 days posttreatment, all three neonicotinoids provided complete control of the strawberry aphid. Though not statistically different, the selective Fulfill showed the presence of non-feeding aphids that had not fallen off the foliage or dried-up compared with those exposed to the other nerve disrupting insecticides.

Table 1.

Mean no./leaflet
Treatment lb(AI)/acre Precount 1DAT 3DAT 6DAT 10DAT

Actara 25WG 0.05 37.1a 8.7bcd 0.0b 0.0b 0.0b
Admire 2F 0.10 31.2a 2.9cd 0.0b 0.0b 0.0b
Assail 70WP 0.04 37.0a 12.7bc 0.0b 0.0b 0.0b
Fulfill 50WG 0.09 35.1a 15.8b 10.9b 4.3b 1.2b
Fulfill 50WG 0.13 36.8a 11.8bcd 5.4bc 3.4b 1.3b
Malathion 57EC 1.75 37.6a 0.0d 0.0b 0.0b 0.0b
Untreated check 36.3a 32.2a 28.4a 23.1a 19.7a

Means within columns followed by the same letter are not significantly different (Tukey HSD test, P<0.05).