Treatment can help save ash trees | News, Sports, Jobs
Ash trees – essentially deprived of water and nutrients by the emerald ash borer – are dying.
How about a little good news? Ash trees do not all have to die.
There is hope, and there is a treatment that can save towering ash trees that are treated with safe, approved insecticides injected by certified applicators, according to Jaime Brinkman, ISA Certified Arborist for Smitty’s Lawn and Landscape in Fort Dodge.
“The treatment we recommend is an injection of a chemical called emamectin benzoate,” Brinkman said. “It doesn’t prevent the pest from entering the tree, but if you have an infestation in your area, you can help fight it.”
Treatments are done every two years and can be started before there is any visible damage to an ash tree. With the rate at which the emerald ash borer is sweeping through Iowa, even healthy-looking ashes are likely to be already infected, especially in much of central Iowa.
Hamilton County saw its first report of emerald ash borer in 2018. In 2020, the emerald ash borer was in Webster County. Wright, Pocahontas and Calhoun counties began reporting cases in 2021. Humboldt and Kossuth counties reported their first cases earlier this spring.
“The emerald ash borer has moved from the southern part of Iowa to the northwestern counties”, Brinkman said. “There are only seven counties left that have not confirmed the emerald ash borer.”
Native to East Asia, the emerald ash borer is a small wood-eating beetle. It was first detected in the United States in Michigan in 2002. The emerald ash borer arrived in Iowa in 2002 and has been making its way across the state ever since. The metallic green beetle lives outside the tree and feeds on leaves. But adults aren’t the problem, according to Brinkman.
“The larvae are what really damage the tree”, she says.
The larvae reside under the bark, tunneling through the phloem and cambium layers, which are responsible for bringing water and nutrients to the tree. The activity of the larvae essentially starves the tree to death.
“It can kill a tree in three to seven years”, Brinkman said.
Look up for the first signs of damage. Infected trees will see a thinning of the canopy.
“Often the emerald ash borer hides in a tree for up to three years before we really see the symptoms,” Brinkman said. “We can treat a tree until there’s a canopy decline of about 30% and have very great success.”
“We don’t recommend waiting to see a 30% drop in canopy,” Brinkman added.
The treatment window is now open, as ash trees should be treated from approximately May to mid to late September, as long as there are leaves on the tree.
The treatment is surprisingly simple. Don’t expect heavy equipment to arrive in the yard, as it all comes in one small bottle of insecticide that is injected directly into the tree, meaning there is no chemical drift.
Will Vaughn is a certified applicator for Smitty’s Lawn and Landscape and described the procedure.
“First, we identify the size of the tree and determine the number of injection sites and the amount of chemical we need to put inside the tree,” he said.
Vaughn looks for root eruptions or places where the root sticks out a little indicating a strong area of the root zone for the tree to feed on. Tiny holes are drilled and a small plug is inserted to guide the chemical to the appropriate areas of the tree to target the larvae. After processing, the holes are barely noticeable. The whole procedure may only take a few hours.
“Our main goal is to get this chemical into that layer of the tree where it needs to go so that it translocates throughout the whole tree,” he said. “The larvae encounter the chemical, ingest it, and it kills the larvae.”
The only visible sign that the tree has been treated will be a small tag, or badge, for record keeping purposes. Of course, the most important sign that it has been treated will be if it keeps its leaves.
An ash tree proactively treated two years ago by Smitty’s at Fort Dodge shows little to no sign of infestation. A nearby ash tree on the same side of the street under the same conditions has started to show signs of canopy thinning. Luckily for this ash tree, it received its first treatment this month, and since the canopy decline hasn’t gone too far, Brinkman and Vaughn expect good results.
“This treatment is both proactive and curative”, Brinkman said.
Treatments will continue every two years until the EAB has completed its work of decimating the population of untreated ash trees.
“He will move out when he runs out of food, and then we can extend those apps to maybe three years,” Brinkman said…
As an invasive species, the emerald ash borer has no real natural enemy in the local environment. But the woodpeckers feed on the larvae. That’s why speckles, or woodpecker damage, are another sign of an infestation. But while people may cheer the woodpecker for trying to reduce the emerald ash borer population, they alone can’t save a tree.
Bird lovers will wonder, will this treatment make birds sick, especially woodpeckers that feed on the larvae? Fortunately, the Iowa Department of Natural Resources has some good news about it, calling it “unlikely.”
Woodpeckers only eat live larvae, so they don’t consume the chemical. If the larvae look tasty for a woodpecker, it hasn’t been treated. In addition, dead larvae decompose very quickly, according to the DNR. And because these chemicals aren’t fat-soluble, they don’t “bio-accumulate in animals.”
The DNR cited Michigan and Ohio as success stories, noting that these states have used such injected insecticides for several years and no cases of woodpecker poisoning have been reported as a result.
Emamectin Benzoate is derived from a naturally occurring soil bacterium and has been used for years to treat fleas on pets. It is also used to control pests in cotton and vegetable fields.
Unfortunately, the DNR has a bleak outlook for untreated ash trees in Iowa. They are almost certain to follow in the path of elm trees that were wiped out by Dutch elm disease in the 1970s.
The DNR estimates that there are approximately 52 million forest ash trees in Iowa and 3.1 million community ash trees. This means a huge loss of habitat, canopy, and woodland resources for the state of Iowa.
To replace the lost ash trees, Vaughn and Brinkman join a chorus to say: “diversify, diversify, diversify.”
Traveling south into Iowa, where the infestation is more advanced, it is easy to see ash windbreaks that were planted to replace elm windbreaks, and now the ash trees are all dead , according to Brinkman.
When shopping for a new tree, look for a variety. Brinkman notes that Iowa is overpopulated with maple trees. For a colorful tree like maple, she says red oak has wonderful color and is one of the fastest growing oaks.
If people like maples, plant one, but don’t plant all maples or all species. Diversity will protect the investment when buying a new tree and create a more interesting landscape.
“The best time to plant a tree was yesterday, the next best time is today”, Brinkman said.