Minnesota’s Ash Trees Are on the Chopping Block

An invasive beetle is ravaging local landscapes. Left untreated, our ash trees will get the axe. Here’s how you can help save the shade.

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Peek out your window. If you can see trees, chances are at least one of them is an ash tree. There are nearly 1 billion of these deciduous trees across Minnesota, and they make up 20 percent of the canopies in our cities. But they could soon disappear.

Since 2009, an invasive beetle called Emerald Ash Borer (EAB) has been chewing through the state’s ash population, killing the trees by disrupting their ability to transport water and nutrients. Once an ash tree becomes infested by EAB, it has an almost zero percent chance of surviving more than three years unless protected prior to infestation.

Here’s how you can determine whether you’ve got an ash tree on your property:

Identifying Ash Trees

There are three types of ash trees in the state—green ash, black ash, and white ash—all of which are susceptible to EAB.

To identify if a tree is an ash, look closely at the bark, leaves, and branches.

  • Bark – Young ash bark is relatively smooth, but as it matures, it develops distinct diamond-shaped ridges. You may also notice the presence of lichens, or a fungus-algae composite, that looks like a leafy crust growing on the bark.
  • Leaves – Look for compound leaves with five to eleven blades attached to a connecting stalk.
  • Branches – Check the branches. Ash trees are opposite branching, meaning their side twigs and leaves grow directly across from one another, like arms.

Still can’t tell? Check out this video for help.

OK, I Think I Have an Ash Tree. What Do I Do Now?

The EAB spends almost its entire lifecycle under the bark, so it can be difficult to look at your tree and easily identify if it’s infested. If your once-thriving ash tree has developed a thinning canopy, though, there’s a good chance you’ve got beetles.  

But whether you think your tree has EAB or not, it’s worth getting an expert out to take a look—and fast. It’s important to proactively treat any ash tree to prevent future infestation, as well as to treat infested trees before they become too damaged to save. Once a tree loses 30 percent of its canopy to EAB, it needs to be taken down.

Thankfully, EAB treatment has a high success rate if done early and properly. Hennepin County recommends hiring an International Society of Arboriculture (ISA)-certified arborist to assess and treat your trees as soon as possible. Treatment should be repeated every two years.

5 Reasons to Save Your Ash Tree

  1. Energy Savings. Mature trees shade your home, reducing air conditioning use in the summer and keeping energy bills low. In fact, one mature ash tree produces the per-day cooling effect of 10 room-sized air conditioners running for 20 hours!
  2. Higher Property Values. Trees can increase your home’s value by up to 20 percent.
  3. Health Benefits. Trees make us feel calmer, happier, and healthier. Studies show that communities with significant ash losses have increased mortality related to cardiovascular and lower-respiratory-tract illness.
  4. Environmental Impact. Each mature ash tree intercepts 2,216 gallons of stormwater, reducing soil erosion and pollution, and eliminates 1,011 pounds of carbon dioxide in the atmosphere per year, decreasing the greenhouse gases that contribute to climate change
  5. Cost Benefits. It’s cheaper to maintain trees than to tear them down. Protecting a tree against EAB for two decades is less expensive than removing a single dead tree. The cost of treating an ash tree for EAB in the Twin Cities Metro is typically between $70 and $200. To help offset the cost even more, 35 municipalities in Minnesota offer discounted treatments to private property owners. (If your city is not on this list, contact your natural resources department or city forester to ask if they have an EAB plan in place.)

Tree removal, on the other hand, can cost anywhere from several hundred to several thousand dollars. Plus, experts recommend replacing any tree you remove, which will cost you an additional $50 to $400. And you’ll still have to wait decades for the tree to mature.

Did You Know?

Once a tree loses 30 percent of its canopy to EAB, it needs to be taken down.

Still Not Convinced?

If you decide not to treat your ash tree, you should consider removing it now. Once trees are infested with EAB they become brittle and more difficult and expensive to remove. If you choose to do nothing at all, your tree will inevitably die. 

The Bottom Line

It’s critical that we protect Minnesota’s ash trees before we lose more of them to the EAB. You can help by maintaining the ones on your property. Consider making EAB treatment part of your regular property maintenance routine. Schedule an ash tree consultation with one of Rainbow Treecare’s more than 50 ISA-certified arborists today.