Invasive little green bugs known as emerald ash borers have been destroying tree canopies throughout the country for years. While some cities have been removing all infected trees, Robbinsdale has using pesticides to treat the ash trees, which account for about 8% of their urban forest, instead of cutting them all down.
Robbinsdale’s forester Stephan Papiz said although the city didn’t officially start seeing the bugs until 2018, he began to treat trees in 2016.
Emerald ash borers may eat a tree for several years before infestation is apparent. Adults lay eggs on trunks and branches in the summer. The larvae hatch and tunnel under the bark. Ash trees are then devoured by the bugs as they grow up. Bugs will emerge later as adults, mate and lay eggs. Unless the ash tree is treated, the tree is fed upon until it dies.
The emerald ash borer, which is native to north-eastern Asia, was first found in Minnesota in 2009, according to the University of Minnesota.
One of the first clues of an infestation is often later-stage blond markings from woodpeckers eating the beetles.
Anyone with an ash tree will either need to chemically treat the trees or take them down. The entire metro is heavily infested with these insects.
Robbinsdale staff will treat approximately 131 trees averaging about 17 inches in diameter this year. Papiz estimates costs to be about $10,000, plus staff time, for the year.
The city of New Hope budgeted $625,000 this year to address tree removal costs . Golden Valley initially had an ordinance requiring homeowners to immediately remove infested ash trees but has since relaxed its city code on ash borers. Many other cities are using a variety of chemical treatments and removal to address the problem.
According to Papiz, Robbinsdale hasn’t lost any city trees to the emerald ash borer, though a few have been taken out due to unrelated reasons. The city maintains about 500 ash trees.
Papiz injects each one personally with emamectin benzoate on a three-year rotation. The chemical kills all the young bugs and stops the tree from being eaten.
Are there side effects to using insecticide? Papiz said emamectin benzoate poses no threat to wildlife, pets or people.
“It goes within the tree, it stays within the tree,” Papiz said. “Ash trees are wind-pollinated. Furthermore, it’s not a neonicotinoid ... [meaning] it does not harm pollinating insects. It pretty much kills specific insects that feed on ash trees.”
The plan is to keep treating the city’s ash trees until they need to be removed for reasons unrelated to the bug. No new ash trees will be planted in the foreseeable future.
Papiz said the city does not manage trees on private property, but he will send letters to any residences when he sees untreated ash trees, asking them to treat them before it’s too late. Several local companies have access to emamectin benzoate, and a list of tree care specialists can be found on Robbinsdale’s website.
Other responsibilities for the city forester include planting new trees, pruning and noxious weed control. Since Papiz started in 2015, he’s maintained a gravel bed nursery where a variety of trees can grow until they’re ready to be planted in public spaces around the city.
The Sun Post asked Papiz why he loves trees so much. He had a lot of reasons, including wildlife habitat, beauty and stormwater impact. Birdtown’s trees are home to songbirds, raptors, bees and others.
In the summer months, trees can provide shade. According to the U.S. Department of Agriculture, a healthy tree canopy can reduce temperatures by 11 – 19 degrees Fahrenheit compared to communities with no tree cover.
According to the U.S. Environmental Protection Agency, trees help manage runoff by limiting erosion, creating a surface area for raindrops to land and evaporate off of and filtering.
Get involved
Through Tree Trust, the city has been selling new trees at $40 each. This year, every Robbinsdale residence can acquire up to two trees. Pickup dates are in May and there are still some available.
Also, there is an Arbor Day celebration at 9:30 a.m. Sunset Park, 3925 Crystal Lake Boulevard, Robbinsdale where 60 free seedlings will be given away.
“[We’ll have] about eight or nine different species,” Papiz described the Arbor Day seedlings. “So there’s something for everyone depending on what fancies their interest or what kind of sight they have. If they an evergreen we have a couple different of those or if they want a fruit tree, we have one of those or if they just want your traditional deciduous tree ... we’ll have [them].”
In May and June, Papiz hopes to pull a lot of garlic mustard, an invasive weed. A group or individual looking for an outdoor volunteer opportunity could reach out.
“The roots are very shallow,” Papiz said. “You just pull it and you pile it, and then you don’t really want to compost it, you want to put it in the garbage where it can be either buried or incinerated. And there’s still a considerable span of that in Sochacki Park.”
Another way to get with the city’s green spaces is to adopt a park. This is an opportunity for a person or group to clean trash from a city park. Usually, the group will pick up trash around Arbor Day, sometime in summer and again in fall. At the annual Arbor Day celebration, caretakers of the parks will be recognized. As of this printing, Lee Park needs to be adopted. Lee Park is at 3738 Lee Ave N. and is 6.7 acres in size. Lee Park has a picnic shelter, a playground, sports fields, a picnic area, paths and trails.
Learn more at bit.ly/3U3m8vK or via email at spapiz@ci.robbinsdale.mn.us.
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