Slow ash mortality approach reduces emerald ash borer numbers
Tools and guidelines are needed for early detection and management of the invasive emerald ash borer (EAB), which has killed hundreds of millions of ash trees since its discovery in North America in 2002. Forest Service scientists tested the use of girdled ash trees for EAB detection and as trap trees or “sinks” to attract beetles and then kill them or destroy infested trees. Low-density EAB infestations were readily detected with girdled ash trees. Injecting trees with systemic insecticide a few weeks prior to girdling produced lethal trap trees that attracted and killed EAB and reduced larval densities. Forest Service scientists and their partners conducted a large multi-agency pilot study to test the Slow Ash Mortaltiy (SLAM) integrated strategy for managing EAB using a combination of tactics including girdled ash trees, regulatory control, public outreach, ash tree removal, and insecticide treatments. While a very small proportion of ash trees in the 150-square-mile project area were treated with insecticide or girdled, both tactics reduced EAB densities and protected ash trees in areas surrounding the treatments. Model results indicate that EAB spread rates are reduced from areas with girdled trees. Trees treated with the systemic insecticide also reduced larval abundance in subsequent years. These research results will lead to improved area-wide management strategies and development of guidelines for forest managers and decisionmakers to control EAB and protect the ash resource.