By Abby Krause, DNR Urban Forestry Coordinator;
Abigail.Krause@wisconsin.gov or 608-556-5690
This summer’s detection of emerald ash borer (EAB) in Burnett County means our little metallic friend (or should I say foe?) is now known to be present in all 72 Wisconsin counties.
While EAB has been around for the better part of two decades in Wisconsin, many homeowners are still in the thick of dealing with the fallout of this invasive pest.
Management options for a handful of individual yard trees present a different challenge than dealing with ash in rural forests.
Here is some information to help smaller landowners with frequently asked questions you may have – or receive from residents, neighbors, family and friends.
My tree has EAB; can I save it?
Photos of ash trees showing various levels of defoliation, often due to emerald ash borer. Ash with more than 50 percent canopy thinning should not be considered for insecticide treatment. / Photo Credits: Eocene Environmental Group, adapted from Smitley et al., 2008
Ash trees that may be infested but have most of their canopy intact can still be treated against EAB. The more live canopy a tree has, the better the chances of a successful treatment. If a tree has too much canopy loss, it does not have a way to pull the insecticide up from the trunk or roots. Trees with more than 50% canopy thinning should be removed.
The other major consideration when deciding to retain or remove an ash tree is cost. EAB treatments are not a one-and-done situation.
Most products available to homeowners are soil drenches containing imidacloprid and are intended for smaller diameter trees with a diameter at breast height of 15 inches or smaller. These typically require a yearly application. Products containing the active ingredient emamectin benzoate offer two years of protection but must be trunk-injected by a professional insecticide applicator.
Recent research suggests some products, when used at the highest labeled rate, may still offer a high degree of protection even when treatments are stretched out to be every three or more years.
Not all ash trees are worth saving. Trees that are smaller in diameter, those with structural problems or poor health or those unsuitably placed in the landscape should be removed. Extending their lives a couple of years through treatment is time better spent establishing a robust replacement.
Depending on the site and state of the trees, temporarily treating larger ash to maintain the canopy cover of the area while non-ash replacements establish nearby is another option to consider.
In instances of healthy, large ash that provide significant services such as runoff or erosion mitigation, reduced electricity costs by shading a home or aesthetic value, it may be cheaper to treat the trees than to remove them. Treating ash trees may be a long-term commitment, and the long-term financial cost should be considered, along with the benefits of retaining live ash. Once insecticide treatments of ash trees are stopped, it should be expected that the trees will be reinfested and killed within a few years.
Where can I find a contractor?
The International Society of Arboriculture (ISA) has a website directory that allows users to search for arborists by location. This will not be an all-encompassing list of available companies but a database of those with ISA professional credentials. The other tried-and-true method is to search local businesses online or scour advertisements in local print media.
If desiring to treat an ash tree, homeowners should look for a company that advertises plant health care as a service. Many will also plainly state they do EAB treatments.
Can homeowners receive DNR grants?
The short answer is “no.” Neither the Wisconsin Department of Natural Resources (DNR) nor any of our partners have dedicated, broadly available funding sources for homeowners to offset the cost of removing EAB-infested yard trees.
Urban Forestry’s annual startup and regular grants are available to villages, cities, towns, counties, tribes and 501(c)(3) nonprofit organizations in or conducting projects in Wisconsin. While eligible applicants can choose to use an Urban Forestry grant to remove trees on private property, homeowners are not eligible to apply directly to this funding.
Partners interested in pursuing an Urban Forestry grant should contact their regional urban forestry coordinator to discuss project eligibility. Urban Forestry grants are open from July 1-Oct. 1 each year for projects in the works for the following calendar year.
Are there other ways to reduce costs?
An overhead photo shows a terrace tree in the public right-of-way that has been killed by emerald ash borer, surrounded by other trees in a neighborhood. / Photo Credit: Wisconsin DNR
First, homeowners should confirm the tree is legally theirs. In many (but not all) cases in Wisconsin, maintenance of trees along streets in the public right-of-way is the responsibility of the municipality. Public trees in terraces (the area between curbs and sidewalks) can be easier to identify vs. trees in rights-of-way that lack a sidewalk. Residents should always contact their village, city or town to determine responsibility for right-of-way trees.
If a tree is near power lines, the local utility should be contacted. The utility will not fully remove trees, but many provide a service to prune a portion of the tree away from energized power lines. A tree worker not qualified to work near power lines can then complete the tree removal.
As with any contractor, homeowners should request a handful of quotes because costs can vary dramatically. Hiring a professional who is fully insured is more expensive but crucial should something go awry during the removal process.
Ash trees infested with EAB become dry and structurally weak. The longer a tree stands, the more expensive and hazardous it will be to remove, especially if it’s too dangerous to climb and is near buildings or other obstacles. If possible, it is best to remove an ash tree while it is still fully or mostly alive.
If the property owner is physically able, they can ask their contractor if there’s a way to reduce costs by doing some of the work themselves. For example, the contractor could simply drop the tree and the homeowner would then cut it up for firewood; or the contractor chips the tree and leaves the woodchips on site for the homeowner to use in their garden and around other trees. Anything saving the contractor time, travel and dumping fees has the potential to reduce costs.
Are there disposal regulations?
EAB was federally deregulated as of January 2021, and Wisconsin’s state quarantine was rescinded in July 2023. However, neighboring states such as Minnesota may still have an EAB quarantine in place. Be sure to check for any restrictions before moving ash materials across state lines.
It is still recommended not to move ash long distances. Using ash from nearby sources helps to slow the spread of EAB into uninfested areas. The DNR’s Urban Forestry program offers recommendations on how to reduce the spread of EAB while utilizing ash as woodchips, firewood or logs as part of the EAB Community Toolbox.
It is also important to note that while EAB may no longer be regulated in Wisconsin, 53 of the state’s 72 counties remain within the spongy moth quarantine. This quarantine regulating wood products and outdoor household items applies both to businesses and private citizens. Additionally, only certified firewood or firewood obtained within 10 miles of a property is allowed onto state lands.