Ever since the emerald ash borer was first found in the Kansas City area three years ago, experts have tracked its spread, waiting for the inevitable time when its population begins to explode.
That time is nearing.
Kevin Lapointe, city forester for Kansas City, says the beetle population is growing faster than expected in his city and will peak in the next year or two. Without treatment, half the ash trees will eventually die.
“The emerald ash borer is going to be financially and environmentally devastating to the metro area,” Lapointe said. “The time to treat is now.”
On the Kansas side, the borer is expanding at an expected pace but still quickly enough to consider treatment this year, Johnson County horticulture agent Dennis Patton said.
The borer, which is native to Asia, has destroyed millions of ash trees in 22 states as it has spread.
The pest first appeared in North America near Detroit in 2002 and was discovered 10 years later in the Kansas City area — in Wyandotte County on the Kansas side and Platte County in Missouri. It has since spread to several other local counties, including Jackson and Clay on the Missouri side, and Johnson and Leavenworth in Kansas.
The borer feeds on both green and white ash, which are native trees in the Midwest and which have been commonly planted, especially during the 1970s through 1990s, to shade its landscape. It can take several years before a tree shows signs of infestation.
Lapointe estimates that there are more than 6 million ash trees in nine counties in the Kansas City region and that they make up 7 percent to 10 percent of the total tree canopy in urban areas and 80 percent to 100 percent in commercial developments.
In the past three years, Kansas City has treated 10,000 to 11,000 public trees and has removed and replaced about 2,000.
“We’re not going to stop this beetle,” Lapointe said. “We’re trying to transition through this next 10 to 15 years so that we’re not losing all the trees at the same time.”
The city has a three-part management plan in place: to treat ash trees every three years by trunk injection; to remove ash trees that cannot be treated over a five- to six-year period, and to replace each of those ashes with a new species.
Owners of the city’s 400,000 private ash trees will have to create management plans of their own.
Patton said ash trees will cost their owners whether they are removed, replanted or treated.
“It should be a personal but informed choice,” Patton said.
Not all ash trees are worth treating, he said. Good candidates are healthy (which can be determined by a tree specialist), are in a good location and have no defects such as rot or decay. In most cases, smaller trees are cheaper to remove than to treat.
For example, Danny Huntsinger, Lenexa parks superintendent, said the city plans to remove all ashes less than 6 inches in diameter. Borer infestations have been found in six locations this spring, according to the city.
Borer treatment options vary in cost but not in commitment.
“It’s not a one-and-done thing,” Patton said. “Once you stop treating the tree, it is no longer protected.”
DIY treatments such as soil drenches and insecticides are done annually and are typically for trees 20 inches or less in diameter. The most common commercial treatment — chemical trunk injection — is repeated every two years.
Treatments by trunk injections are more expensive but, especially for larger trees, are more effective. The cost of treatment depends on the size of the tree and also the rate of chemical used.
Wayne White, a board-certified master arborist based in Michigan, has been following the borer outbreak since the beginning. He estimates that he has treated 150,000 trees across Michigan, Ohio, Indiana, Illinois and Wisconsin.
“I think they were more optimistic about their ability to slow it down,” White said.
White and others recommend that homeowners begin treating their ash trees if they are within a 15-mile radius of a known infestation.
Treatment can be effective at the beginning of an infestation, as long as no more than 30 percent of the canopy has been damaged, Lapointe said.
Local companies are already busy.
Erik Stewart, branch manager at TruGreen Lawn Care, said one two-person crew now works exclusively to treat borer infestations in the Kansas City area.
Ryan Lawn Care has workers out every day treating for the borer, said Steve Klecan, plant health care department manager. The company saw a spike in calls in May when homeowners realized that neighboring trees were damaged, he said.
VanBooven Tree Care also has been busy since mid-May, said Brad Hatfield, an arborist with the company, which expects work to wrap up in early July.
Soil treatments can be done anytime after the ground thaws. Injections must be administered when the tree is in full leaf so that the chemical can move through its vascular system.
Local experts agree that although the ideal window for treatment — April and May — has passed, treatments are still effective.
But not for long.
“Treat now,” Lapointe said. “Treatment opportunities are quickly diminishing, and options (other than injections) will be gone in the next year.”
Signs of infestation
▪ Thinning canopy
▪ Branch and limb dieback
▪ Shoot growth at base of the tree
▪ D-shaped holes near the base of the tree
▪ Damage by woodpeckers
Tips for hiring
Kevin Lapointe, city forester for Kansas City, suggests keeping a few things in mind when hiring a tree specialist:
▪ Hire only a certified arborist with at least three years experience and insurance.
▪ Get at least three estimates.
▪ Instead of getting an individual bid, get a group of homeowners together to cut the cost.