The emerald ash borer (EAB) is a green beetle native to Eastern Russia and much of Asia. Outside of its native region, it is an invasive species and is highly destructive to ash trees. EAB was first noted in Michigan in 2002 and has since spread through the upper Midwest. It is believed to have been introduced to North America through shipping crates/pallets from Asian sources. Currently (2015) the EAB infestations have been found in Michigan, Ohio, Wisconsin, Minnesota, Ontario Canada, plus perhaps another ten to fifteen states. Evidence suggests the EAB can spread between ten and twenty miles per year. This spread is enhanced by transport of firewood and other wood products that contain ash bark, which allows EAB to spread to new areas to create satellite populations outside of the main infestation and quickly increase its range.

The EAB is almost totally destructive of native ash trees. After the initial infestation, all ash trees in the area are expected to die within ten years without control measures. The ash species affected in southeastern Minnesota include green ash, black ash, white ash, and blue ash. EAB seems to infect ash trees in the order listed here; i.e., green and black first, then white, and finally blue ash.

Winona County is under a quarantine order issued by the United States Department of Agriculture (USDA). The City of Lewiston is, therefore, also within an EAB infested area and subject to regulations of the USDA. EAB will inevitably spread throughout the City and cause the loss of all ash trees.

The City of Lewiston needs to determine a course of action to address the EAB threat to its ash tree population. This EAB Management Plan is written to outline Lewiston’s objectives and the methods to be used in dealing with the impact of EAB on our ash trees. It is also to be used as a guide for City administration and residents to follow with a high degree of confidence and order. The City will need to create an EAB management budget to meet the costs of tree removal and/or treatment as well as public education. This plan will address both public and private needs in an efficient and effective manner, including replacement of removed trees with diversification of species and utilization of ash wood that is removed. This plan, therefore, will lessen the social and economic impact from the impending EAB infestation.

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