Invasive beetle killing more trees
City to replant different species
By James Card
At this time of year, woodpeckers are hammering on ash trees in search of the larvae of the emerald ash borer (EAB), an invasive beetle that is annihilating ash trees throughout the Midwest.
The woodpeckers’ activity create a condition called “flecking” that results in the outer bark of an ash tree to flake off, leaving pale blotches on the upper trunk and limbs.
As a result, the ash trees die a slow death.
The EAB larvae tunnels under the bark and feeds on the tree tissue that moves water and nutrients up and down the trunk. A small tree will die in a year or two. A big ash tree will die in three or four years.
Ground zero for the local destruction of ash trees is the Waupaca River.
Upstream of County Trunk Q, dead ash trees are scattered in every direction. In the summer when other tree species are lush with green leaves, the skeletal limbs of dead ash trees stick out through the canopy by the hundreds.
It was here in the town of Farmington where the presence of EAB was confirmed in 2017 by a pheromone-baited trap.
In 2020, the beetle was found in ash trees in the city of Waupaca.
Waupaca River corridor
“The Waupaca River corridor has been the main EAB spread because it needs ash to spread. It’s spread pretty much all the way down to the Wolf River by now,” said Michael Schuessler, a Department of Natural Resources forester who serves Waupaca County.
There are three species of ash native to Waupaca: black, green and white. White ash grows in more upland areas and the EAB will attack this species only after the green and black ash have died off. Black ash prefers swamps and green ash tends to grow in river bottoms. Black and green ash are common along the Waupaca River.
There are a couple of other pockets in Waupaca County where EAB has spread and Schuessler suspects that those spots appeared because of EAB-contaminated firewood was transferred to the sites.
The EAB doesn’t fly any father than necessary – just to the next ash tree. Previously only certain counties with EAB were under quarantine, which meant firewood could not be moved outside the county line.
Now, the entire state of Wisconsin is under quarantine for EAB and wood products (firewood) can move freely within the state but not outside of the state and into non-quarantined areas.
How bad is it?
Unlike Dutch elm disease where the elm tree has a chance to grow and reproduce with seeds, the EAB kills ash trees before they are mature. They never get a chance to produce seeds.
Even after the beetle destroys a stand of ash trees, a small population remains to kill off any re-growth.
“A low-level population will always remain. The EAB feeds on stems that are typically bigger than an inch in diameter. For those trees that were not killed the first time around, there will be some that stay in the area, and then when those young trees get bigger, they will come back and feed on those. It would have to be a fairly long period of time without any trees growing before you could declare an area free of emerald ash borer,” said Schuessler.
Ash trees have disappeared in the Great Lakes region in record numbers and there is a possibility that younger generations might not ever see an ash tree. The U.S. Forest Service started a program save ash seeds for long-term storage as a hedge against extinction. Information can be found online on how to identify and collect ash seeds.
To save individual ash trees, such as one growing in a backyard, there are insecticides that can be injected into the tree. More applications are needed every 1 to 3 years and that is not a guarantee that the tree will survive.
Some trees that are already infested may not be worth it and it is better to remove the tree entirely.
Replanting the loss
This month the city of Waupaca was awarded $2,500 grant from American Transmission Company (ATC), an organization that owns and operates thousands of miles of electric transmission lines throughout the state.
ATC has a keen interest in forestry issues because they must keep the power lines clear of trees that could potentially make contact with energized lines and create a power outage.
Dead ash trees killed by EAB are a threat to their operation.
“We’re excited to be able to plant a variety of trees to replace those that were removed because of emerald ash borer,” said Justin Berrens, the city’s public works director. “With this grant from ATC, we’ll increase the diversity our tree population, as well as provide additional shade and natural beauty within the city.”
Community Planting Program
ATC has a Community Planting Program for cities to plant trees that will offset the loss of ash trees. The only caveat is that the trees are not planted inside transmission line rights-of-ways.
The trees species to be planted are Japanese tree lilac, hybrid elms, Kentucky coffee tree, hawthorn, ginkgo, catalpa, linden, hackberry, horse chestnut and sycamore.
For private landowners looking to replant trees to replace the dead ash, Schuessler suggests to match a tree species that can thrive in similar conditions of black and green ash.
For lowland sites that flood and have substantial wet conditions, he recommends tamarack and black spruce. For river bottoms, silver maple, red maple, hackberry and swamp white oak are good choices.
For trees with little commercial value, willow and cottonwood are options.
“We’re at the point where we have to capture the site,” said Schuessler, meaning that if native trees are not planted in the place of ash, an invasive species like reed canary grass has the potential to colonize the spot. Reed canary grass is considered one of the worst invasive species in Wisconsin and it prefers to take over the same kind of habitat along the Waupaca River where the green and black ash used to grow: wetlands, moist meadows and riparian areas.
“Planting trees in water up to your knees isn’t easy,” Schuessler said. “And deer are going to browse them off without some sort of protection. It’s a tough battle all around.”