How do I know if an ash tree can be treated for emerald ash borer or needs to be removed?

Question

I have 16 Emerald ash trees that have been hit with the emerald ash borer. While I have seen the ash borer's bore holes and the epicormic sprouting of branches in random places, I question whether or not these trees can be treated or if they indeed have to come down. I've had four experts come out and give me estimates, all of whom have said that all 16 trees need to come down, that simply treating them will just cost even more money because the treatment will be an ongoing thing. Removing all trees will cost anywhere from $6,000 to $9,000 depending on the company while treatment will only be a few thousand.

How do I know these experts are genuine in their assessments that the trees need to be removed and not just treated, especially when all they've done is walk up and down the lot and do little more than look at them?

Answer 1

Updated September 2015

Where is it found

This pdf shows where Emerald Ash borer is found in the United States. It is also found in Ontario and Quebec in Canada.

How bad can the damage get

From here: If you can see damage from the beetle then

Surveys have shown that the emerald ash borer damages and kills trees in stands within one to four years of infestation. Typically, within six years of an infestation arriving in a woodlot, more than 99% of the ash trees have been killed.

What can a homeowner do

This decision guide indicates that if your trees do not show damage and are less than 20" diameter you can treat them yourself with a range of pesticides or with TreeAzin. This is preventative rather than curative.

If you can observe signs of the emerald ash borer in your ash trees then it's over for them and quick removal is the best solution. The longer you delay the more likely that the ash borers will multiply and spread to other ash trees in your neighbourhood. Delaying means additional costs comes out of your neighbor's and your city's pockets.

Here are the signs to look for that will confirm whether removal is the best solution.

• D shaped holes in the trunk that are one eighth of an inch in diameter. Native borers make larger circular holes
• frass or sawdust below the exit holes confirm that a local or emerald borer is present
• two to five inch vertical splits in the bark
• heavy woodpecker activity indicates pest activity
• dieback from the top of the tree indicates pest activity
• does your local city/municipality have information on the emerald borer? Are there maps indicating if the borer is present?

See here for details.

If you don't see any of these then get one of the companies back and have them justify their opinion.

You may choose to treat the trees but this has to be done regularly and will be an ongoing cost for many years. See here for details about hiring an arborist.

Once a tree shows signs of more than 20% dieback due to EAB, treatments may not be successful. Treatment should be considered primarily to prevent the infestation of healthy trees.

All of the available insecticide treatments need to be repeated every year

There are no guarantees that available treatment options will work.

There are many trees that are not attacked by emerald ash borer. One that is most resistant to everything is the Gingko tree.

Answer 2

Contact your county's local agriculture extension that works with your land grant university. They won't have the financial interest of a tree service and so you can feel comfortable that their answer is honest.

Answer 3

Topics answer depends on what percentage of crown remains alive. 30% or less damage is treatable consensus between experts today. Oddly not one of those diagnosing Arborist proclaimed trees were too damaged to recover with treatment. Not even one from the 16 in various conditions. Be aware that any existing damage will adversely effect insecticide uptake. And even though good possibility tree recovers once EAB free, crown could be misshapen for years to come. **Is treatment needed for rest of trees life, like those four experts "theorized"? ** Scientific field studies in part of Mi. where EAB first arrived revealed fact that danger from damaging "infestation" population thresholds inevitably subsides within 12-15 years of first local detection, once Borers kill off their remaining "Untreated" food source. Here is link to video containing scientific details. https://youtu.be/2R3ef1WT5yc

EAB does not infect or disease trees like Dutch elm disease does, and they do not bore deeply into structural heartwood...National Park service is patriotically protecting Jefferson's 200 old Green Ash w/300 yr. lifespan at Monticello, and George Washington's 250+ old White Ash with 600 year possible lifespan. Tip: Always get several quotes since not every certified Arborist is an EAB expert! Official Source http://emeraldashborer.info/