Black Stem Borer

Black Stem Borer, Xylosandrus germanus (Blandford)

Black stem borer (BSB), Xylosandrus germanus, a non-native ambrosia beetle established in the US for over 80 years, is causing increasing damage in NY and other northeastern states. Normally a pest of hardwood trees, BSB has been documented in dozens of NY apple orchards since 2013, causing tree death and decline in mostly young dwarf apple plantings by excavating galleries in the trunks, resulting in tree losses of up to 30%.  These borers primarily attack physiologically stressed trees (e.g., from flood, drought, or cold injury) that are emitting ethanol volatiles. We have been using ethanol traps to document their occurrence and timing in over 50 NY orchards, and have also tested different preventive treatments to protect the trunks from BSB attack, using waterlogged potted apple trees (to stress them into producing ethanol) placed in the orchard and in adjacent woodlots.  Protective trunk insecticide sprays have been only marginally effective, so current efforts are focusing on incorporating a repellent secondary host plant volatile that is found in bark beetle pheromones and acts as an anti-aggregation signal, to combine with trunk sprays as a “push-push” tactic against this pest.  BSB carries and cultures a symbiotic fungus in the trunk galleries as food for its brood, and has associations with an array of additional microorganisms, some of which are pathogenic.  We are collaborating with Kerik Cox’s program (Plant Pathology and Plant-Microbe Biology) to characterize the fungi and bacteria present in BSB infestation sites and their potential contribution to tree decline and death.  Further collaborative efforts involve investigation of potential microbial control measures and the assistance of Cornell Cooperative Extension  specialists and educators, in documenting BSB occurrence and distribution in regional trapping trials.

Publications & Resources

  • Monitoring, Repellent Trials, and the Relationship of Tree Stress to Attack by Ambrosia Beetles in NY Apple Orchards – ARDP Final Report 2018 https://blogs.cornell.edu/agnello/files/2018/12/BSB-Final-Report.2018.Agnello-1gkzdzc.pdf
  • Monitoring and Management Tactics for Control of Ambrosia Beetles in NY Apple Orchards – ARDP Final Report 2017 BSB Final Report.2017.Agnello
  • Agnello, A. M, Breth, D. I., Tee, E. M., Cox, K. D., Villani, S. M., Ayer, K. M., Wallis, A. E., Donahue, D. J., Combs, D. B., Davis, A. E., Neal, J. A., and English-Loeb, F. M.  2017.  Xylosandrus germanus (Coleoptera: Curculionidae: Scolytinae) occurrence, fungal associations, and management trials in New York apple orchards. J. Econ. Entomol. Vol. 110. Agnello et al.JEE.2017
  • Agnello, A., D. Breth, E. Tee, K. Cox, and H.R. Warren.  2015.  Ambrosia beetle – an emergent apple pest.  NY Fruit Quarterly.  23(1): 25-28. NYFQ Spring 2015 article
  • Evaluating Threat Level, Infestation Behavior, Economic Impact and Potential Measures for Control of Ambrosia Beetles in NY Apple Orchards – ARDP Final Report 2016 BSB Final Report.2016.Agnello
  • Evaluating Threat Level, Infestation Behavior, Economic Impact and Potential Measures for Control of Ambrosia Beetles in NY Apple Orchards – ARDP Final Report 2015 Agnello.Ambrosia beetles report.ARDP.2015
  • Gilrein, D.  2011.  Ambrosia Beetles in the News. Branching Out 18(8), 2 pp. Gilrein.Branching Out.2011

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