Emerald Ash Borer Management

EAB photoEmerald Ash Borer (Agrilus planipennis Fairmare, also known as EAB) is a beetle from Asia that entered the United States through wood packing material around 2002, through the Port of Detroit, Michigan. EAB was discovered in Wisconsin in 2008.

EAB as an adult beetle does little damage, but the larvae feed just beneath the bark of ash trees and cut off the vessels which transport nutrients and water. EAB has killed tens of millions of ash trees in the U.S. and Canada since its discovery.

Know your Ash Trees

  • Compound leaves
  • Distinctive bark pattern
  • Opposite branching
  • Seeds

Signs and Symptoms of EAB infestation

  • Crown dieback
  • D-shaped exit holes
  • S-shaped larval tunnels
  • Woodpecker feeds

West Allis Forestry EAB Injection PhotoWhat is the City doing?

As of 2018, the City is treating approximately 3,300 City-owned ash trees. West Allis Forestry maintains street trees, boulevards, City right-of-ways, landscaped areas at Municipal buildings and parking lots, in addition to the City parks. Currently, West Allis Forestry maintains approximately 20,000 trees city-wide.

Treatment for EAB is applied on a 3 year cycle. About 1,000 ash trees that are not candidates for treatment or are located under utility wires are being systematically removed at the rate of approximately 200 trees per year. These trees are being replaced with different species to diversify the City's urban forest and protect City trees from future pest infestations and diseases.

What happens to trees that are removed by the City?

Many trees removed from the urban forest eventually end up being turned into mulch for landscaping, pallets to move goods, or firewood to be burned. Urban lumber has many higher uses: construction materials, furniture making, and crafting/hobby arts.

Are removed trees replaced?

West Allis Forestry attempts to replace as many trees as possible every year. In spring 2018, Forestry planted approximately 600 trees throughout the City. Trees planted in 2018 can be identified by the white paint on the top of the tree stakes used to keep the tree in place.

What can property owners do?

Ash trees can be saved if they are chemically treated. Trees may need to be treated throughout their lives. If your ash tree is healthy and is enhancing your landscape, it may be worthwhile to protect your tree. Healthy trees are valuable and provide many benefits such as home energy savings, increased property value, shade, and reducing storm water runoff. For more information on chemically treating ash, see Wisconsin Emerald Ash Borer Click on the 'Homeowners' tab for further links on tree or insect identification as well as chemical options.

If your tree is already infested, is structurally unsound, or is otherwise in poor condition, it should be removed. Ash trees left untreated will ultimately become infested. Trees killed by EAB become a liability because the dead limbs become very brittle, making their removal more difficult.

Whether you decide to treat or remove your ash trees, get as many estimates as you can to make sure you are getting a fair price. Select an arborist that is both insured and bonded, which protects all parties involved. Before any work begins, get a written description of all work to be performed. For help finding an arborist visit Wisconsin Arborist Association and click the 'Arborist for Hire' button to find available arborists in your area.