Evaluation of a single application of Neonicotnoid and multi-application contact insecticides for flatheaded borer management in field grown Acer rubrum L. cultivars

Authors: OLIVER, J - Tennessee State University; Fare, Donna; YOUSSEF, N - Tennessee State University; Scholl, Sue Sue; Reding, Michael - Mike; Ranger, Christopher; Moyseenko, James; HALCOMB, M - University Of Tennessee

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2010
Publication Date: 9/1/2010
Citation: Oliver, J.B., Fare, D.C., Youssef, N., Scholl, S., Reding, M.E., Ranger, C.M., Moyseenko, J.J., Halcomb, M.A. 2010. Evaluation of a single application of Neonicotnoid and multi-application contact insecticides for flatheaded borer management in field grown Acer rubrum L. cultivars. Journal of Environmental Horticulture. 28(3):135-149.

Interpretive Summary: Flatheaded borers can significantly impact the production of nursery stock for up to four years after transplanting, causing mortality or rendering trees unmarketable due to trunk scaring. In this study, non-insecticide-treated red maple cultivars sustained high levels of flatheaded borer damage in 2005 (2.5'19.0%) and 2006 (32.1'41.0%) trials, indicating almost half of the crop was lost without insecticide protection. All of the borers reared from damaged trees in this study were flatheaded appletree borer (Chrysobothris femorata [Olivier]) (FAB), which indicated flatheaded borer species are important in red maple production in middle Tennessee. Untreated plants and plants ineffective treatments continued to sustain FAB damage every year, indicating a common misconception that borer attacks only occur during the first year after transplanting. Current recommendations to prevent FAB damage are trunk sprays of Dursban during mid May and mid-to-late June; however these applications did not provide for acceptable borer control. Drench formulations of Discus and Allectus provided excellent control and were more effective than other imidacloprid formulations like experimental tablets and gels during the first and second post-treatment year. Experimental imidacloprid tablets provided complete FAB control in years 3 and 4, suggesting the tablet formulation eventually releases enough imidacloprid to protect trees or that small quantities of imidacloprid released by this product eventually achieve levels in the tree sufficient to prevent FAB. Discus and Arena 50WDG (clothianidin) drenches applied in March were more effective than May applications, suggesting early season application provides an advantage in achieving greater insecticide concentrations in the trunk from root uptake and translocation. Trunk diameter growth was greater with Discus and Safari compared to other treatments, which indicates these neonicotinoids can increase the value of trees, since sales price is often based on trunk caliper size.

Technical Abstract: Two trials evaluated insecticides for flatheaded borer (Chrysobothris femorata [Olivier]) control and red maple (Acer rubrum L.) cultivar growth over a 4-year period. Soil-applied systemic insecticides (acephate, imidacloprid, clothianidin, dinotefuran, and thiamethoxam) and trunk-applied contact insecticides (chlorpyrifos and bifenthrin) were tested. In the 2005 trial, a one-time drench of Discus (imidacloprid + cyfluthrin) or Allectus (imidacloprid + bifenthrin) provided 2 to 4 years of protection with ‘Autumn Flame’ and ‘Franksred’ from C. femorata. Soil-applied experimental imidacloprid tablets prevented borer damage in the third and fourth post-treatment years, but were not as effective as imidacloprid drenches in the first two years. Soil applied acephate tablets, chlorpyrifos (Dursban 4E) trunk sprays, and untreated control plants had borer damage each year which totaled up to 41.7% damage by year 4 with ‘Autumn Flame’. Trunk diameter growth was greater with Discus drench and imidacloprid tablet treatments and maple canopy growth was greater with Discus and imidacloprid tablets than other treatments. In the 2006 trial, Allectus, Discus (May- and March-applied), Safari 20SG (dinotefuran), and Arena 50WDG (March-applied) (clothianidin) drenches provided complete C. femorata prevention during the first year with ‘Fairview Flame’, ‘Franksred’, and ‘October Glory’. Discus (March) drench provided four years of complete protection among the three cultivars, while other neonicotinoid drenches had 5.1-6.3% (Arena March and Discus May), 0-7.7% (Safari), 7.7-12.8% (Arena May), and 12.5-20.5% (Flagship) total damage. Ineffective treatments among the three cultivars included an experimental imidacloprid gel (12.8-18.8% damage), acephate tablets (28.2-75.0%), Onyx Pro (5.1-18.8%), Dursban 2E (17.9-31.3%), one imidacloprid tablet (2.6-43.8%) and untreated controls (37.5-41.0%). During the study, only C. femorata were reared from test trees. This study demonstrates that a single application of neonicotinoid at the right rate and timing can provide multi-year C. femorata protection, increased maple trunk growth, and provide superior protection to trunk sprays.