Save An Ash Tree Program



Emerald Ash Borer (EAB) is spreading throughout Wisconsin and threatening our ash trees. It takes

several years and is 100% lethal if the tree is not treated with the appropriate insecticide. To prevent

this devestation to our ash population, the City of Edgerton has purchased special equipment to injec

t insecticide into the city-owned ash trees in parks and along streets.


However, due to costs, the city budget allows us to save only a portion of our public ash trees.  These

are our largest ash trees and the majority of them are locfated along the city streets.  Help save one

or more other publich ash trees!


Why? A 10-inch diameter white ash tree provides about $97 in overall benefits each year. If the tree

continues to grow to 15 inches, it will provide $181 in annual benefits (National Tree Benefit Calculator). In addition, the cost to save an ash from emerald ash borer destruction can be less than the $500-$1000 cost to cut down an infested or dead tree, remove the wood and replant a new tree in its spot. And, most likely, the new tree would be much smaller than the original ash.


How do I know if an ash on the street terrace in front of my house is one of the trees scheduled to be treated by the city?

You would have received a letter from the City letting you know if your street tree is targetd for treatment. If not, please consider sponsoring it for treatment.


When? The best time will be in spring. The insecticide works best when applied in May and June, but can be applied in September, depending on temperatur and rainfall. The emerald ash borer has been found in southern Rock County and might already be here. Once the borer has burrowed into a tree, it is harder to protect the tree from dying, though it is possible to save a tree with less than 50% canopy dieback. We need to take preventative measures now.


How much will it cost to Save-an-Ash? A tree that has a 10" diameter at breast height (dbh) or about a 30" circumference will cost approximately $50.00. The treatment will last 2 years. That is a cost of only $25.00 per year. Every two years, participants will be notified that they can opt to re-treat the tree (s) they adopted for an additional cost.


What if the ash I adopted becomes infested with EAB? Studies show that the chemical (Azadirachtin A&B) we will use for treatment is 99% effective for at least 2 years. In the case that a treated tree declines in health or dies due to EAB or another cause, the city will remove and replace the tree.


How do I know my ash tree is infested?

Typically, the tree starts to die at the top and it may start to sprout around the base or along the trunk. Borer emergence holes are D-shaped but are hard to detect when they are at the top of the tree.


Who is responsible for the ash trees if they die? On city land, the city will remove trees. These areas include the street terrace, boulevards and parks. In your yard, you are responsible for its removal and proper disposal of the debris.


Can I treat an ash tree myself? No, if the tree is on public property, including the street terrace. Contact Public Works Director for permission. Yes, if the tree is on your own private property. A professional arborist might use an insecticide injection system like the city or s/he might use a soil drench. Consider which type of application you would like. The injection system goes directly into the tree and does not affect the surrounding soil and plants. With the soil drench, the insecticide is poured onto the soil around the base of the tree. It is then taken up by the roots of the tree. Note that the soil drench is an annual application. If your tree is greater than 50 inches in circumference, professional treatment is recommended.


  • If using a professional service, we recommend using an insured, certified arborist.

  • If doing it yourself, please refer to the UW Extension webpage for Homeowner guide to EAB.



          Official Website of the City of Edgerton, 12 Albion St, Edgerton, Wisconsin 53534 (608) 884-3341 Rock & Dane County