Season-long Management of Drosophila suzukii in Southern Highbush Blueberry, 2014

Abstract

Blueberry | Vaccinium spp. spotted wing drosophila | Drosophila suzukii (+) cis/trans 3-(2,2-dichloroethenyl)-, 2,2 dimethylcyclopropane carboxylate; 3-bromo-1-(3-chloro-2-pyridinyl)-N-[4-cyano-2-methyl-6-[(methylamino)carbonyl]phenyl]-1H-pyrazole-5-carboxamide; alpha-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate; Chromobacterium subtsugae strain PRAA4-1T; Cyantraniliprole; Fenpropathrin; Malathion; N-(Mercaptomethyl) phthalimide; S-(O,O-dimethyl phosphorodithioate; O, O-dimethyl phosphorodithioate of diethyl mercaptosuccinate; Phosmet; Pyrethrins; S-Cyano (3-phenoxyphenyl)methyl; Spinetoram; spinetoram-J; spinetoram-L; Spinosad; Spinosyn-A; Spinosyn-D; Zeta-cypermethrin The objective of these trials was to determine efficacy of season-long insecticide programs against SWD in southern highbush blueberries. Trials were conducted at the University of Georgia Blueberry Research and Demonstration Farm in Alma, GA. We evaluated four treatment programs each consisted of weekly applications of differ-ent insecticides (Table 1). Treatments were organized in a random-ized complete block design with four blocks of four treatments and an untreated check. The plots were approximately 0.14 acres and in-cluded 3–5 rows of blueberry bushes. Insecticides were applied weekly from May 2014 to June 2014 at the manufacturer-recom-mended maximum field rate with a standard airblast sprayer. Water was used at the rate of 50 gpa for the foliar spray applications. Induce (nonionic surfactant) was added at the rate of 1 pt/100 gal of total spray volume to all Exirel treatments. All sprayer nozzles were open with the exception of the top two nozzles and the bottom noz-zle on each side to insure coverage of the target surfaces and reduce drift. The sprayer tank and the filter were rinsed three times before making the next application. A shoot with 5–10 leaves and five ripe berries was cut from a blueberry bush from each plot and placed into the bioassay cham-ber. The bioassay chambers were constructed using 32 oz clear plas-tic deli cups (Fabri-Kal, Plastics Place, Kalamazoo, MI). Blueberry shoots were inserted into Oasis 4 inch single anchor water picks (WholesaleFloral.com, Williamsville, NY) containing 10 ml of wa-ter. The water picks were placed through a fitted hole in the bottom of a deli cup. The berries were placed into a wire mesh (1/4 inch wire mesh) boat placed at the bottom of the deli cup. Fly diet (yeast:sugar:water mix), 7 ml of water, and a dental wick (House Brand Plain Wrapped Cotton Rolls 1–1/2 inch by 3/8 inch, no. 2 Medium) were all placed through a parafilm lid covering a soufflé cup (Solo p050-0100 0.5 oz). The chambers were covered using 32 oz clear plastic deli lid (Fabri-Kal, Plastics Place, Kalamazoo, MI) with a 2 by 2 inch mesh (white tulle) opening. Ten even-aged adult SWD (five males and five females) from our laboratory colony were introduced into the bioassay chambers, and mortality was evaluated at 1, 3, and 5 d of exposure. Samples were collected 1, 3, and 7 d af-ter treatment (DAT). Data were arcsine-square root transformed and analyzed using analysis of variance. Tukey–Kramer HSD was used to compare the means (a ¼ 0.05). The results (Table 2) show that export-friendly, short preharvest interval and reduced risk programs provided significantly higher mortality of SWD than untreated check throughout the season until 3 DAT. However, residual efficacy of Imidan, Mustang Maxx, and Danitol lasted for up to 7 DAT. The SWD mortality in organic pro-gram was statistically similar to untreated check except for Entrust at 1 DAT in week 3.