In this article with The Lowdown, Justin Bence and Nate Shaw, from Davey's North Minneapolis office, tell readers about EAB and why it's important to plant different varieties of trees.
Posted: May 27, 2016
By Jackie Bussjaeger
According to arborists Justin Bence and Nate Shaw of Davey Tree Expert Company, you never really know whether or not your tree is infested with the invasive beetle emerald ash borer (EAB). The beetle is entering its breeding season, and the effects of infestation may be more visible in neighborhood trees as the greenery—or lack of—begins to show.
Eleven Minnesota counties, including Anoka, Ramsey and Washington, currently have a quarantine in place to prevent the spread of EAB. The quarantine bans the transport of any EAB insects, all wood or parts taken from ash trees and even firewood made from any hardwood tree from crossing county borders in an effort to control the swiftly spreading pest.
Ash trees are prevalent in Minnesota, especially because they flourish in this climate and are good low-maintenance shade trees. They were a popular choice for replanting common areas after Dutch elm disease decimated the elm population, Shaw said. Now that EAB is beginning to eradicate local ash trees, maple is a common choice for public spaces and residential areas. However, choosing many different kinds of trees to plant rather than just one or two will ultimately be the best protection for tree health.
“Tree variety is very important,” Bence said. “You don’t see many varieties, but they’re definitely beneficial to have.”
As homeowners and cities begin to replace the damaged ash trees, Bence recommended maple, honey locust, hackberry and swamp white oak as a few potential replacements.
There are three major signs that strongly indicate the presence of EAB: dying branches (especially high in the canopy), damage from woodpeckers that are seeking the EAB larva for a good meal and new green sprouts along the lower trunk, known as water sprouts, trunk sprouts or sucker growth. These lower sprouts indicate that the tree cannot provide nutrients to its higher branches, likely from blockage caused by EAB larva.
EAB is undiscriminating when it comes to selecting trees to attack—the health of the tree is irrelevant to the beetle, which sets it apart from other native beetles species that feed on ash trees. This is a huge part of what makes the infestation so devastating, especially in Minnesota’s ash-friendly climate.
“Emerald ash borer attacks healthy trees. Native borers only go after trees that are stressed,” Shaw said. “It’s so fast, in Chicago trees we were keeping track of were half defoliated within three to four months. Most tree problems don’t happen that quickly.”
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