March 28, 2024

Emerald ash borer larvae found in Osceola

The Emerald ash borer (EAB) is deceptively small. The metallic green insect is no bigger than a dime, and yet, experts say it could wipe out 99 percent of the country’s ash tree population.

On Monday, Nov. 28, the Iowa Department of Agriculture and Land Stewardship (IDALS) identified EAB larvae in Osceola.

“Ash trees within 15 miles of a confirmed emerald ash borer site are at the highest risk for attack,” said IDALS EAB and Gypsy Moth Coordinator Mike Kintner.

EAB feed on all species of ash, though black, green and white are most at risk. The insects lay their eggs in the xylem, the woody tissue under the bark. Once hatched, the larvae spend up to a year eating the tree away from the inside out. This disrupts the flow of nutrients through branches and accounts for the strange die-off patterns seen in infestations, in which crowns die first.

“Trees with up to 30 percent canopy die-back can be treated,” Kintner said. “It is safe to say nearly all untreated ash trees will die.”

While it isn’t likely a homeowner will notice the small holes EAB use to deposit their eggs, the larvae attract the attention of woodpeckers, especially in winter. The larger, D-shaped exit holes the beetles make once they’ve matured are easier to spot. So are the suckers – the smaller limbs sprouting from around the base of a tree that’s already dying from the top down. The progression is unsightly, but it gives homeowners a chance to get ahead of the problem.

“Two or three years after that initial detection, it becomes much more obvious. We are already noticing this in other communities,” Kintner said. “EAB usually kills an ash tree two to four years after it is infested.”

Unfortunately, preventative treatments aren’t effective this late into the season, according to an IDALS release. Homeowners with ash trees on their property should begin looking now for the right expert to perform treatments beginning in April.

“Depending on the size of the ash tree and method of application, treatments can be applied either by a professional with a commercial pesticide applicator license or by the homeowner,” Kintner said.

Insecticides are needed to eradicate and prevent infestation. No natural solutions have been discovered. However, there is one chemical option safer than the alternatives, and it’s one of the most effective.

Trunk injections are often better at preventing infestations than treating the bark or the soil. Some commercial treatments, such as emamectin benzoate, provide more protection, while others need to be repeated yearly alongside another type of treatment to keep the beetles away for good. Then, there is the need to find an applicator who is certified by IDALS Pesticide Bureau at either the 3O or 3OT levels.

“Cost depends on the size of the tree. That’s determined by the diameter at chest height,” said Shane Blakely of Blakely Tree Service in Osceola. “It’s roughly $10 per inch. Those treatments last for two years.”

Blakely uses TREE-äge trunk injections to manage EAB infestations.

“That’s what they’ve used for about nine years,” he said. “The ash borer came to Michigan in ’02. It took about four years to find a solution to protect those trees.”

Unfortunately, in the time it took to develop TREE-äge, Michigan ash were nearly completely wiped out.

Blakely has been treating trees for EAB for the last three years. While no insects had been spotted in Osceola previously, they’ve been in Union County since 2014. Experts knew the migration was inevitable. While the insects fly up to 15 miles from where they spawn, they can also travel in firewood, wooden storage containers and similar items, which is why areas with known infestations often come under quarantines banning them from exporting ash products.

“The pesticide I inject circulates through the tree and the root system. Those eggs will instantly die,” Blakely said.

But, that isn’t the only reason he prefers TREE-äge.

“Another benefit to the injections is I can treat a tree on a playground or next to a pond or a river or one with pets or kids playing around it, because everything is sealed inside the tree,” he said.

According to IDALS, it’s also recommended that you work with a professional applicator who is also a certified arborist. The size and health of your tree will determine whether treatment or removal is the best remedy for an infestation, so working with a tree expert often saves time and prevents future problems.

“I have 2,000 to 3,000 ash trees back in our timber,” Blakely said. “I don’t know how many I’ve cut down.”

Nothing will save forest populations unless they can be treated. That’s bad news for the 55 million ash trees growing throughout Iowa and for the ecosystems relying on the shade they provide.