Carol Stream, Roselle battling ash borer

Roselle is mixing chemicals.

Carol Stream is sharpening the ax.

Both are among many DuPage County towns battling the emerald ash borer this spring, as the pest continues to infest and ultimately kill ash trees throughout the region.

Roselle this week is treating 635 trees, about one-third of its more than 1,700 total ash trees on public property, as part of a plan the village board adopted this spring. Roselle discovered the infestation last year.

A private arbor company will treat the village’s ash trees with a chemical called imidicloprid, which will be drenched into the soil and injected into the trunks. Village forester Mike Schulz said the chemical is not harmful to children or pets.

Roselle officials said preserving the trees is a priority because they are considered part of the village’s infrastructure. But workers also have cut down nearly 100 trees arborists said couldn’t be saved, and remaining trees will be cut if they begin to decline, Schulz said.

“If they’re not infested we might as well enjoy them while they still stand,” Schulz said. “There is also no guarantee they will all be infested, but we suspect they will be over the next seven years.”

Schulz said any trees left standing years from now could have strong resistance, which might help breed future ash tree populations.

Roselle’s treatment program is a multiyear effort that will cost nearly $27,000 during the first year. The program is ultimately prudent, officials said.

“At an average of $42 per year to treat each of the (635) ash trees, it is estimated that if left untreated, the eventual removal would cost over $1,000 per tree,” village spokeswoman Melissa Brito said in a statement.

The locations of the publicly owned ash trees slated for treatment are posted at roselle.il.us/EAB, and the trees will be tagged with an aluminum marker.

Village officials haven’t decided what efforts will be made to reforest Roselle.

When the emerald ash borer was discovered in Carol Stream in 2007, village officials decided not to immediately begin removing infected trees. Arborists had recommended against clear cutting because it had proved ineffective in other parts of the country in stemming the pest’s advancement, said Phil Modaff, public works director.

But this spring, many ash trees began to show signs of serious decline that will make their removal necessary, Modaff said.

“We know they’re declining and we know they’re not getting better,” Modaff said.

Many trees have been able to survive the infestation for years, but the signs of the borer’s effect have become evident: bare shoots sprouting out from the main tree trunks.

Two village arborists are now working on an assessment of the village’s 2,500 ash trees on public property — which make up 35 percent of the village’s total tree stock — to see how many have to be removed. Modaff said he expects removals to begin this summer and last for the next couple of years.

About 30 trees were removed this winter in the older part of town, where arborists began their audit.

Carol Stream has an existing contract with a tree removal company, but the village could also go out to bid for additional work, depending on the extent of the borer infestation.

Modaff didn’t have an estimate on how many trees will have to be removed.

The village purchased more than 2,000 trees at the St. Aubin Nursery that will be planted on the village parkway in place of removed ash trees.

The village will fund tree removals and replacements with $2.25 million the village board set aside in 2007.