By Deborah G. McCullough and and Rodrigo J. Mercader
East Lansing, MI (October 2011) – Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive pest native to Asia, has killed millions of ash (Fraxinus spp.) trees in North America since it was first discovered there in 2002. As of autumn 2011, A. planipennis has been detected in 15 US states and two Canadian provinces.
A pilot project to slow the onset and progression of ash mortality, termed SLAM (SLow Ash Mortality), has been implemented in localized A. planipennis populations. Here we use spatially explicit simulations to evaluate the potential of a recently developed systemic insecticide to protect the ash resource in urban forests as a component of the SLAM approach.
Over a 10-year horizon, simulations showed ash survival varied depending on: (i) how soon insecticide treatment began after the A. planipennis introduction; (ii) the proportion of trees treated; and (iii) the distribution of treated trees relative to the A. planipennis introduction point.
Annual treatment of 20% of ash trees annually protected 99% of trees after 10 years, and the cumulative costs of treatment were substantially lower than costs of removing dead or severely declining ash trees.
According to communications about the research with Deborah McCollough:
“While this is a hypothetical setting, our EAB models are based on data from several of our field trials. We have confidence that they are quite accurate and reflect the progression of ash mortality as EAB populations build. The cost data we used are from actual city foresters—it included product costs, travel costs, equipment+administrative costs, and so forth. They were using in-house labor for treatment with TREE-age and for tree removals. In this situation, the best option was treating 20% of the ash trees annually. The trees were randomly selected and we assumed treatment did not begin until 4 years after EAB became established in the area. That protected 90% of the 2300 ash trees in the area for the ten-year period at cumulative cost of about $364,550. In contrast, the cumulative cost of removing trees as they died (no treatment) was $1.9 million.”
Evaluation of potential strategies to SLow Ash Mortality (SLAM) caused by emerald ash borer (Agrilus planipennis): SLAM in an urban forest
Arborist recommends plan to treat, rather than remove, ash trees infested by bug