Jeffrey Hahn, Asst. UMN Extension Entomologist
A position statement was released in January strongly advocating the conservation of ash as a part of an integrated pest management program, along with tree inventories and strategic removal / replacement of unhealthy ash. Cost-effective, environmentally sound emerald ash borer (EAB) treatment protocols are now available that can help preserve ash trees. This document is supported by a combination of university scientists with expertise in EAB management, commercial arborists, municipal foresters, public works officials, and non-governmental organizations (NGOs).
This is a very important document that should help guide us as we deal with EAB in Minnesota. Below is the text for the document. To see the original document, click here, http://www.emeraldashborer.info/files/conserve_ash.pdf
Coalition for Urban Ash Tree Conservation
- Emerald Ash Borer Management Statement -
Emerald ash borer has killed millions of ash trees since its discovery in 2002 and the number of dead ash is increasing rapidly. Ash species are abundant in planted and natural areas of urban forests, representing 10 - 40% of the canopy cover in many communities.
Ash trees provide substantial economic and ecosystem benefits to taxpayers, ranging from increased property value, to storm water mitigation, to decreased energy demands (http://www.coloradotrees.org/benefits.htm) ( this link is no longer available).
Consequently, widespread ash mortality in urban forests and residential landscapes is having devastating economic and environmental impacts. Indeed, EAB is predicted to cause an unprecedented $10-20 billion in losses to urban forests over the next 10 years. (http://ncrs.fs.fed.us/pubs/jrnl/2010/nrs_2010_kovacs_001.pdf)
After its initial discovery, regulatory agencies attempted to eradicate EAB through removal and destruction of all ash trees in infested areas. Unfortunately, this proved unsuccessful and was soon abandoned.
Based on research conducted by university scientists, and careful review of the potential impacts on human health and the environment, the Environmental Protection Agency (EPA) has registered three systemic insecticides for control of EAB - dinotefuran is registered for basal trunk bark or soil application, emamectin benzoate for trunk injection only, and imidacloprid for soil application or trunk injection.
When applied using formulations, products, and protocols documented as effective by university research, these treatments can provide environmentally sound control of EAB, sufficient to maintain a functional and aesthetically pleasing ash canopy.
Treatment is most appropriate after EAB infestation has been detected within 15 miles, and is most effective when applied before trees are infested. However, treatment can also save ash trees with a low level of EAB infestation. Spring is the ideal time for treatment, but soil application in fall can be effective in some situations.
Different treatment regimens will be optimal under different situations -- no one treatment plan or application method is best under all circumstances.
A program of sustained treatment will be needed to conserve trees through peak EAB infestation. However, as the local EAB population declines due to death of untreated ash, it is possible that treatment frequency may be reduced. Research on this question and other aspects of EAB management is ongoing, requiring practitioners to stay current.
Up-to-date information about EAB insecticides, application protocols, and effectiveness can be found at: http://www.emeraldashborer.info/file/multistate_EAB_Insecticide_Fact_Sheet.pdf
In summary, urban ash conservation can be less costly than removal, especially when the significant environmental and economic benefits of established trees are considered (www.treebenefits.com, http://extension.entm.purdue.edu/treecomputer/). Furthermore, ash conservation can circumvent the substantial environmental impacts caused by wholesale deforestation of the urban landscape, as well as the documented public safety risks associated with standing dead ash trees and their removal. [See original document (link above) for authors and their affiliations]