Emerald ash borer arrives in Southwest

Three infested trees found in Lakewood Cemetery

An adult emerald ash borer. The beetle's larvae damage ash trees when they bore underneath the trees' bark. Credit: File photo

EAST HARRIET — Emerald ash borer was found in three ash trees in historic Lakewood Cemetery in January, meaning the invasive beetle has finally found its way to Southwest nearly five years after its discovery in Minnesota.

It was one of three new infestations announced Friday by the Minnesota Department of Agriculture. The two others were in St. Paul.

Minneapolis Park and Recreation Board Director of Forestry Services Ralph Sievert said a member of his crew was driving along Kings Highway on a sunny January day when he spotted two ash trees missing a significant amount of bark. Woodpeckers strip the bark off of infested ash trees in pursuit of borers.

“He thought, Uh oh, that looks pretty suspicious,” Sievert said.

Sievert and the employee went in for a closer look and saw “two woodpeckers going to town.” They also peeled back the bark from the trees and found the telltale S-shaped bore holes left in the wood by the beetle’s larvae.

Minnesota Department of Agriculture entomologist Mark Abrahamson used the same techniques to confirm the infestation. It’s likely more of the cemetery’s ash trees are already infested with emerald ash borer, Abrahamson said.

Lakewood President Ron Gjerde said there were about 700 ash trees on the cemetery’s grounds. Ash trees account for 10–15 percent of the cemetery’s forest by Gjerde’s estimation, but they soon will be replaced by other species.

“If we wanted to spend the money to treat them, it can be a never ending process,” he said. “… This might actually be an opportunity for us to start eliminating [the ash trees] and introducing a variety of species, and actually enhancing the cemetery”

It’s a process the cemetery has been through before. Gjerde said the cemetery was devastated by Dutch elm disease and also lost a significant number of trees in two tornadoes about 30 years ago.

Abrahamson said both Minneapolis and St. Paul were taking a proactive approach to emerald ash borer that should blunt its impact somewhat, even though ash trees make up roughly one-fifth of the urban forest in Minneapolis. Forestry crews in Minneapolis are selectively removing marginal ash trees and replacing them with other species, and at the same time remain vigilant in spotting the signs of full-blown infestations.

“The thing about emerald ash borer is we always knew it was a losing battle, and it’s just a matter of making it a manageable problem,” he said.

Both Ramsey and Hennepin counties remain under a quarantine that strictly limits the movement of firewood and other tree products. Emerald ash borer is most likely to spread through the transportation of infested wood products, Abrahamson said.