White ash tree canopy at Arcadia Dunes. Photo courtesy of Grand Traverse Regional Land Conservancy.
By Vic Lane
Senior Conservation Project Manager, Grand Traverse Regional Land Conservancy
Emerald Ash borer (EAB) is a non-native, invasive, insect pest that originated in Asia. Its larvae feed on the living tissue of numerous species of ash trees, quickly cutting off the flow of vital nutrients and water. Arriving in southeast Michigan in 2002, it was met with early quarantine and eradication efforts that were unsuccessful. Over the last 20 years, the borer has spread throughout Michigan ⸺ killing tens of millions of ash trees, primarily green, white and black ash. EAB is now having similarly devastating effects on much of the rest of the U.S. and Canada.
As early as 2004 and 2005, EAB was found in Manistee, Benzie, and Grand Traverse Counties. It is suspected that larvae were transported north in firewood that included infested ash trees.
During summer of 2013, EAB arrived at the Grand Traverse Regional Land Conservancy’s Arcadia Dunes Nature Preserve, which straddles the county line between Benzie and Maniste.
While efforts to protect trees at the forest scale are not feasible, individual trees could be treated with an insecticide that kills the ash borer. The conservancy selected nine healthy white ash trees, along the edge of the “Big Tree Loop” trail, to treat and manage as legacy trees. This effort is meant to ensure future generations of families, naturalists, and school children will have access to mature ash trees in a natural forest setting. Within a decade, many of these trees will be approaching 30 inches in diameter.
To continue to protect our northern Michigan Forests for future generations, Grand Traverse Regional Land Conservancy is preparing to launch its “Regional Forest Protection Program” this year. The program seeks to promote resilience of our region’s forests to threats of invasive pests, changes in climate, and fragmentation through prioritized and coordinated efforts of private landowners and partners. Using the tools of voluntary land protection, forest stewardship, demonstration, and connecting landowners to existing resources, GTRLC is working to secure a legacy of healthy forests for future generations. For more information about GTRLC and our work, please visit our website: www.gtrlc.org or email us at info@gtrlc.org.
Saving an Ash Grove
Editor’s note: The below information will be included on a new interpretive sign to be installed beside the treated ash grove in Arcadia Dunes.
Although never a dominant tree species like maple, beech, and hemlock, White Ash was an important component of this mesic northern forest. But in 2013, the Emerald ash borer arrived here, killing nearly all the ash trees at Arcadia Dunes.
Emerald ash borer (EAB) is an exotic beetle that was discovered in southeastern Michigan in 2002. The adult beetles nibble on ash foliage but cause little damage. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients. The insect makes quick work to kill the trees ⸺ often it takes only a single season.
In anticipation of emerald ash borer, the conservancy contracted an arborist to treat nine large ash trees along the scenic “big tree” loop to Baldy. These lucky trees were selected for their size, proximity to the trail and likelihood of survival. They are intentionally clustered in one section of the trail for easy, cost-effective treatment. Treatment involves injecting an insecticide directly into the trunk of the tree. Trees are retreated every couple of years.
The conservancy plans to treat these trees for as long as there are funds and hopes that an alternative solution is found to curb this invasive species. As of 2021, researchers are pursuing biological control with tiny parasitic wasps which prey on emerald ash borers.
So far, this grove of ash has survived the attack and continue to thrive. The intention of the treatment was not to save the species, but rather to provide an opportunity for us to remember, and for our children to see, what a 30-inch diameter ash tree looks like.
