Battle against tree-destroying insect continues statewide

By Kristine Gill

kgill@vindy.com

AUSTINTOWN

Officials at Mill Creek MetroParks haven’t seen an emerald ash borer in the area since they plucked one from a glue trap set in 2008.

The purple trap was one of 23 set around Mill Creek Park as part of a statewide effort to track the spread of the invasive bug, which reached Ohio in 2003 and is now in 14 other states. It was first found in Mahoning County and reported to the U.S. Department of Agriculture on June 19, 2007. Emerald ash borers already have killed millions of ash trees across the country and could destroy the tens of thousands in Mill Creek Park if they can’t be stopped.

Ellen Speicher, assistant horticulture director for the parks, said the single bug didn’t cause much alarm. It likely entered Hitchcock Woods when someone transported infested firewood along the nearby turnkpike. Nontheless, the find was a reminder of the imminent damage the insects will cause. “It’s a sad situation,” Speicher said, lamenting the potential loss of trees that make up 8 percent to 10 percent of the park’s forestry. “It will be devastating when they get here.”

Until recently, removing the trees when they were infested and sometimes before they were destroyed seemed the best option. Now some experts are promoting the use of FDA-approved insecticides that would kill the bugs and save the trees.

The Coalition for Urban Ash Tree Conservation, a group of 21 tree experts and university professors, released a statement in January encouraging cities to consider treating ash in urban settings to preserve those environmental benefits they provide.

Anand Persad, a technical advisor and entomologist with the Davey Tree Institute in Kent, said the loss of so many trees in one area would have significant consequences.

“We’d certainly lose some eccosystem benefits of the ash tree. We would lose wildlife, the aesthetic appeal would be impacted. Trees in general provide windbreaks; they help curb amount of rain that hits soil in a certain amount of time,” he said.

But Speicher said Mill Creek can’t afford to treat trees with chemicals.

“The problems with treating trees is that it’s a yearly process,” she said. “You can’t just treat the tree once. Some arborists recommend it’s [being] treated twice a year. It’s an expensive proposition ... with a success rate of 50 to 90 percent. Sometimes it’s successful, but sometimes you lose the tree anyway.”

Speicher said the park has a list of all healthy ash trees, and trees that could be hazardous when infested.

“We have taken down ash trees in very poor condition, trees that would have been taken down regardless,” Speicher said. “We haven’t started taking down healthy trees. We would love to avoid that, but there will come a time when there is a tree over a structure — a cabin or a road — that could be dangerous.”

If more emerald ash borers have since spread to Mill Creek, the irridescent insects won’t be spotted until late spring when the adults emerge from the bark after feasting and growing all winter.

Tiny, stingless wasps known to be the emerald ash borer’s natural predators in their native land of China were first released in Michigan in 2007 to attack its larvae and eggs. A few thousand were released in Ohio and other states in 2009. According to a report from the Department of Agriculture, the wasps had spread and could survive harsh Michigan winters.

They weren’t found to provide a significant level of control like their counterparts in China, but scientists believe some native insects also have learned to attack the emerald ash borer.

The invasive species was first identified in Detroit in 2002 and likely came to the country on shipping containers from China. It’s estimated that the bug was boring into ash bark as early as the 1990s but remained undetected until experts looked further into what they thought was a case of Ash Yellows disease felling the trees. It can take five years before a borer kills a tree.

And though the emerald ash borer quickly drew attention, it isn’t the only pest responsible for widespread tree loss in the country. The Asian Gypsy Moth and the Asian Longhorned Beetle created similar problems when they were introduced in the 1860s and 1990s respectively. Diseases such as Dutch Elm disease and Oak Wilt claimed thousands of others in the 20th century.

“One of the reasons why emerald [ash borer] is such a formidable pest is because we have a lot of ash and they’re in close proximity to each other,” Persad said.

There are 16 species of ash trees in the country. They grow quickly, they’re cheap, and they can be used for a range of products including baseball bats and hardwood floors.