ARS | Publication request: Drench Treatments for Management of Larval Japanese Beetle (Coleoptera: Scarabaeidae) in Field-Grown Balled and Burlapped Nursery Plants

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 2008
Publication Date: August 1, 2008
Citation: Oliver, J., Reding, M.E., Dennis, S., Moyseenko, J.J., Youssef, N., Klein, M.G., Callcott, A., James, S., Mcanally, L., Bishop, B. 2008. Drench Treatments for Management of Larval Japanese Beetle (Coleoptera: Scarabaeidae) in Field-Grown Balled and Burlapped Nursery Plants. Journal of Economic Entomology. 101:1158-1166.

Interpretive Summary: Japanese beetle is an important horticultural pest of ornamentals and is now widely distributed in the eastern United States. The larvae of the beetle (grubs) are readily transported in the soil of nursery plants. Consequently, the movement of nursery plants that are potentially infested with Japanese beetle into western and mid-western states continues to be a regulatory issue. The U.S. Domestic Japanese Beetle Harmonization Plan (developed by the National Plant Board) governs the treatment requirements for moving nursery stock between Japanese beetle infested and non-infested states. Presently, there are only two treatment methods are approved for Japanese beetle certification of field-grown nursery stock to allow shipping from infested to non-infested states. In the southern U.S., many nursery producers must also treat nursery crops against imported fire ants. Development of a treatment method that could be used for control of Japanese beetles and fire ants would significantly reduce labor costs and amounts of insecticides used. The objectives of this study were to test a treatment method, surface drenches to post harvest nursery trees, and insecticides approved for fire ants for control of Japanese beetles in nursery crops. In addition to test the effectiveness of reduced-risk insecticides applied by this same treatment method. We found that two insecticides approved for fire ant control were also effective at controlling Japanese beetle when applied as drenches to root balls of post-harvested ornamental trees. In addition, a reduced-risk insecticide was also effective at controlling Japanese beetles when applied as a drench to root balls. These results indicate that nursery growers in southern states could apply one set of treatments and control both fire ants and Japanese beetles to a level that satisfies quarantine requirements, which should also result in considerable labor and insecticide savings compared to applying separate sets of treatments for each pest.

Technical Abstract: The study evaluated insecticide drenches applied to post-harvest field-grown nursery plants harvested as 60-cm diameter balled and burlapped (B&B) root balls for controlling third instar Japanese beetle, Popillia japonica Newman. Bifenthrin, chlorpyrifos, lambda-cyhalothrin, and thiamethoxam were drench-applied in fall and spring tests at volumes of runoff (1x; 2.57 liters per drench per root ball) or twice runoff (2x). Tests also examined consecutive drench number (2, 4, or 6) and B&B rotation between drenches. Fall-applied drenches did not meet the Domestic Japanese Beetle Harmonization Plan (DJHP) standards defined in the Nursery Accreditation Program (i..e., <= 1 grub). However, most fall-applied drenches significantly reduced grub numbers compared to the control treatment. Spring-applied drenches had less grubs than fall-applied drenches. All spring-applied chlorpyrifos treatments had < 1 grub per treatment (94.4'100% control). Other spring-applied treatments were less consistent, including thiamethoxam (83.3'100% control) and bifenthrin (61.1'100% control), but had > 1 grub per treatment at six consecutive drenches. Lambda-cyhalothrin was not effective (0.0'14.3% control). A higher drench volume (2x) did not significantly increase grub control over a 1x volume for any insecticide. Grub numbers decreased linearly as drench number increased from two to six for fall-applied chlorpyrifos and thiamethoxam and spring-applied bifenthrin. Rotation of root balls significantly reduced grub numbers compared to non-rotated treatments for fall-applied chlorpyrifos (6 drenches) and bifenthrin (2 or 6 drenches), but differences did not meet DJHP standards. The study indicates chlorpyrifos, bifenthrin, and thiamethoxam drenches can control Japanese beetle in the spring and may provide a new post-harvest option to certify B&B plants for Japanese beetle.