Emerald Ash Borer Dilemma: Remove Trees or Treat Them?

Last year, 10 ash trees in Plainfield had to be removed because they were infested with emerald ash borers. This year, it will be 50, and that is likely just the beginning of what is expected to be a mass infestation of the tree-destroying beetles.

“Some arborists have said this is pretty much the equivalent of a natural disaster,” Scott Schirmer of the Illinois Department of Agriculture told the Plainfield Village Board Monday night.

“Ashes were a great street tree. They were durable, cheap … nobody saw this coming.”

TJ Countryman, the arborist who heads the village’s forestry division crew, said the village has about 6,000 ash trees on public parkways and on other public property. No one knows for sure how many might be on private property, but the number could be as high as 25,000, he said.

Most of Plainfield’s infected trees are in the northern portion of the village, Countryman said. The Champion Creek subdivision is where the 50 trees will be removed this fall, he said.

Up until now, the village’s policy has been to cut down the trees in which the borer has been found, in part because once the insect is discovered, it’s too late to save the tree. But there are ways to treat trees at the early stages of infestation or before they become infected, Schirmer said.

The village – and homeowners – must decide the cost-effectiveness of trying to save trees versus removing them and replacing them with other types of trees, he said.

“We’re going to have to come to grips with what we’re going to do financially,” Trustee Jim Racich said. “The problem is at our doorstep and it’s not going to go away.”

Acknowledging that point, the board asked Public Works Director Allen Persons to prepare a cost-benefit analysis for the various options available so a plan of attack can be established.

Emerald ash borers, which are native to Asia, were first discovered in Michigan in 2002, Schirmer said. They were likely transported here in ships carrying goods or packing materials from Asian countries, and then moved to other states via firewood, cars and trucks, and people’s clothing, he said.

So far, the beetle been confirmed in 15 states and two Canadian provinces, and has killed more than 40 million trees, Schirmer said. The worst-hit states are those that surround the Great Lakes Basin: Michigan, Indiana, Illinois and Ohio.

In Illinois, it was first discovered in St. Charles in 2006 and is now in 18 counties. The first cases in Plainfield were confirmed last year, officials said.

It’s difficult to determine if an ash is infected because the beetle is green and and about the size of a grain of rice, and the bulk of the damage done by larvae feeding on the wood can’t be seen, Schirmer said. The beetle lays eggs so small you can fit five on the head of a pin, he said.

Because they tend to attack the top of a tree first, the first sign of infestation may be dead spots in the upper branches, he said. If a tree begins to sprout bushy new growth at its base, that’s a sure sign the tree is infected and making a last-ditch effort to survive before it dies, Schirmer said.

“The tree basically gets strangled off,” he said. “(The beetles) are pretty lazy. They tend to stay on the same trees pretty much until they’re dead.”

Illinois and other states have laws prohibiting the movement of firewood between states in an attempt to slow the borers’ progress, but in many cases it’s impossible to enforce because those who are moving the wood are individuals who may not be aware of the laws, he said.

As for treatment, there are three ways to try to protect a tree or reduce the infestation if it’s already present, Schirmer said. Insecticides can be poured around the base of the tree, injected into the trunk or sprayed on the bark.

Thus far, most of the procedures have varying success rates that are sometimes dependent on the tree not yet being infected, he said.

And even if a particular chemical is found to have an 80 percent effectiveness rating, that still means that 20 percent of the beetles in the tree will survive, he said.

A relatively new treatment called TreeAge, which is pumped into the tree trunk, is being found to be 98 percent to 99 percent effective, but it’s not been around long enough to know the long-term effects, Schirmer said.

Applying insecticides can be expensive because it must be done on a regular basis, he said. In some cases, especially for trees that are very young or very old, removal is the most cost-effective thing to do, he said.

For homeowners, the dilemma can be more complex. Removing trees might have a dramatic and negative effect on a property’s appearance and/or value or a tree may have a sentimental value, such as one planted as a memorial or to commemorate an event, Schirmer said.

There is also the expense of removing a tree. While a small tree might be taken down for less than $100, a mature tree can sometimes cost thousands of dollars, he said.

Countryman said he has been advising people they might consider planting a new tree before taking down their ash so the effect on their property is not so large.

Village Administrator Brian Murphy, a Detroit-area native who previously worked in a Michigan town that had emerald ash borers, said being prepared is key.

“If (the trees) go as fast as they did in the last town I was in, our crews won’t be able to keep up,” he said.