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Evaluation of Insecticides for the Economic Control of Winter Moth in Blueberry, 2002

Evaluation of Insecticides for the Economic Control of Winter Moth in Blueberry, 2002

L. K. Tanigoshi and J. R. Bergen
Washington State University
Vancouver Research and Extension Unit
Vancouver, WA 98665-9752
tanigosh@wsu.edu, bergenj@coopext.cahe.wsu.edu

Winter moth, Operophtera brumata (L.) and Bruce spanworm, O. bruceata (Hulst) have increasingly been reported as economic, early season pests of blueberries grown in Oregon and Washington. The eggs of both species are laid during late fall and early winter. Growers often missed detection of the early hatch of these emerging moths in March to mid-April when temperatures average about 55 oF. Larvae are difficult to control because the first instar larva will burrow into and feedon unopened buds. Maturing larvae are difficult to detect until they have migrated from bud to bud and visible damage has occurred to these fruiting bodies and surrounding foliage. Winter moth larvae were collected from opening fruit buds in mid-April from Woodlands, WA and from English Laurel foliage in mid-April from Whatcom County . Six reduced risk products were tested and compared with Diazinon and Capture standards. Insecticides were applied in aqueous suspensions using a Potter Spray Tower with 2 ml of each concentration applied to 4 inch blueberry fruiting twigs. These were air dried, placed in a water-dental wick-vial in a 6 inch Petri dish held at lab temperature with one winter moth. These replicated trials were observed 5-6 days after treatment for larval mortality.

For 2 of the 3 Potter tower bioassays, bifenthrin (Capture®) at the red raspberry and strawberry rate of 0.1 lb(AI)acre expressed 100% mortality after twenty-fours posttreatment. Bifenthrin shows an excellent potential use on blueberry for larval Lepidoptera and root weevil. Secondly, the synthetic avermectin analogue Proclaim® showed excellent control of winter moth larvae both after twenty-fours hours and 100% mortality at either 5 or 6 days posttreatment. This compound was also given potential use status on the IR-4 new products/transitional solution list, July 2002. Indoxacarb (Auvant®), the recently registered spinosad (Success®) and the insect growth regulator methoxyfenozide (Intrepid®) performed consistently well at several rates, especially after 2-6 days posttreatment. All three of these compounds are considered reduced risk products and Auvant and Intrepid have been given pending use status for blueberry by IR-4. Generally, the other insecticide tests showed significant differences from the untreated check in most cases 5 days after treatment (Tables 1-3).

Table 1. Lynden, WA, 8 May 2002.

Percent Mortality
Treatments lbs(AI)/acre 1DAT 2DAT 5DAT

Avaunt WG 0.09 40ab 40bc 60a
Intrepid 2F 0.25 60ab 80ab 100a
Proclaim 5SG 0.01 100a 100a 100a
Success 2SC 0.10 80a 100a 100a
Untreated check 0b 0c 0b

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

Table 2. Lynden, WA, 23 May 2002.

Percent Mortality
Treatments lbs(AI)/acre 1DAT 3DAT 6DAT
Actara 25WG 0.086 0a 20ab 100a
Avaunt WG 0.045 0a 20ab 100a
Avaunt WG 0.11 0a 40ab 100a
Capture 2EC 0.10 40a 100a 100a
Intrepid 2F 0.12 20a 40ab 100a
Intrepid 2F 0.25 0a 0b 100a
MVP II 0.50 60a 60ab 100a
Proclaim 5SG 0.008 40a 60ab 100a
Proclaim 5SG 0.015 0a 0b 100a
Success 2SC 0.019 40a 80ab 100a
Success 2SC 0.049 40a 40ab 100a
Untreated check 0a 20ab 20b

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

Table 3. Woodland, WA, 18 April 2002.

Percent Mortality
Treatments lbs(AI)/acre 1DAT 2DAT 5DAT

Actara 25WG 0.086 73abc 80a 87a
Avaunt WG 0.09 73abcd 100a 100a
Avaunt WG 0.045 60abcd 87a 93a
Avaunt WG 0.065 67abc 73a 93a
Avaunt WG 0.11 53abcd 93a 93a
Capture 2EC 0.10 100a 100a 100a
Diazinon 50WP 0.50 80abc 87a 87a
Intrepid 2F 0.12 67abcd 93a 100a
Intrepid 2F 0.25 53abcd 60a 87a
MVP II 0.50 60abcd 73a 80a
Proclaim 5SG 0.008 73abc 93a 100a
Proclaim 5SG 0.010 80abc 100a 100a
Proclaim 5SG 0.015 87ab 93a 100a
Success 2SC 0.019 27cd 73a 87a
Success 2SC 0.03 33bcd 73a 93a
Success 2SC 0.049 47abcd 73a 93a
Untreated check 13d 13b 13b

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