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Onion Maggot and Seed Maggot Management in Onion Using Insecticide-Treated Seed 2002

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Project Leaders: B. A. Nault, Dept. of Entomology, NYSAES-Geneva

R. W. Straub, Dept. of Entomology, NYSAES-Highland

A. G. Taylor, Dept. of Hort. Science, NYSAES-Geneva

Cooperators: J. van der Heide, NYS Cooperative Extension, Oswego County

C. MacNeil, NYS Cooperative Extension, Ontario County

C. Hoepting, NYS Cooperative Extension, Lake Plains Veg. Prog.

M. Ullrich, NYS Cooperative Extension, Orange County

Type of Grant: Pheromones; biorationals; microbials; conventional pesticides

Project Locations: Research is applicable to locations where onion is grown.


Novel seed treatment chemistries that provide a high level of onion maggot and seed maggot control in onion were investigated. Laboratory experiments were conducted to evaluate how well seed treatments protected the onion plant from onion maggot when plants were infested at varying ages with varying densities of maggots. Younger onion plants tended to be more likely to be killed or damaged by onion maggots than older ones. Plants also were more likely to be killed at onion maggot densities of 5 and 10 eggs per plant than at a density of 2 eggs per plant. With the exception of cyromazine (Trigard), all seed treatments reduced the overall percentage of onion plants killed by onion maggot. Although spinosad (SpinTor) and fipronil (Icon or Mundial) were not effective against onion maggot when plants were 2-weeks old, they reduced the percentage of plants killed by maggots when plants were older (4 to 8 weeks). Thiamethoxam (Cruiser) provided the best protection from onion maggots when plants were young (2 to 4 weeks old), but efficacy waned as plants got older. All of these chemistries were effective against seed corn maggots, although cyromazine was the weakest. In the field, spinosad, fipronil and GUS-I (experimental product) provided the best protection of the onion crop from onion maggots, whereas cyromazine and thiamethoxam also provided an acceptable level of control. Onion maggot control using cyromazine failed in laboratory, but worked well in the field. Thus, more research is needed to identify the factors and mechanisms responsible for this disparity. Commercially applied formulations of fipronil provided excellent control of onion maggot in three major onion-growing areas in NY, indicating that fipronil will be an effective tool for onion maggot control when it becomes commercially available. Additional studies are required to evaluate fipronil and other seed treatments for controlling seed maggot infestations.

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