Learn to spot emerald ash borer
By Heather Thorstensen
hthorstensen@agrinews.com
Date Modified: 12/21/2011 4:09 PM
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DAKOTA, Minn. — Ken Schauland of Lewiston thinks it's likely that the destructive tree pest emerald ash borer is coming to his Lewiston property.
At a nearby infestation site on Nov. 14, he and approximately 50 others learned exactly which signs indicate the pest may be present. The Minnesota Department of Agriculture and Minnesota Department of Transportation hosted the field day north of Nodine to educate the public.
"There's no substitute for seeing it first-hand, what these things look like," said Mark Abrahamson, an entomologist with MDA.
If landowners spot borers on their property, they shouldn't move wood from ash trees because that could put the bugs in a new area. Quarantines on ash products are already in place in Ramsey, Hennepin, Houston and Winona counties. The borer has also been found in northeastern Iowa.
Residents could also decide to take down infested trees to slow the spread of borers.
The pest infests, and ultimately kills, ash trees. One key sign is holes in tree bark, evidence of woodpeckers.
"Woodpeckers tell us for sure there is a bug in the tree," Abrahamson said.
To know whether that bug is emerald ash borer, get under the bark at the hole. Only emerald ash borers leaves behind shallow tunnels in zig-zag patterns as it feeds on a tree's nutrients.
Other signs on the bark are vertical splits and D-shaped exit holes where the adult beetles emerge. Residents who suspect they see these symptoms should contact MDA for a diagnosis.
Equipped with orange safety vests, field day participants examined trees and found white larvae.
The best time to scout for infested trees is winter time, said Jonathan Osthus, the emerald ash borer biological control coordinator at MDA. It's easiest to spot symptoms after trees lose their leaves. In late winter, a whole season of woodpecker damage is evident.
Tom Lindsey, another Lewiston resident at the field day, is treating his most valuable ash trees with pesticides to prevent a future infestation. These are the trees that provide shade to his home and they wouldn't be easily removed if they died.
"If it's as bad as they say it is, I'm going to fight the battle eventually," Lindsey said.
Deciding when to use treatments is up to homeowners, based on how much risk of losing their ash trees they're willing to take, said Abrahamson. He recommends landowners seek professional help if they decide to treat trees. It's important that they start putting a plan in place for what they will do if borers move into their area, he said.
The field day was held on a right-of-way owned by MnDOT located next to the Kwik Trip at exit 267 of Interstate 90. The site, approximately 60 miles from Rochester, has the heaviest borer activity that Abrahamson has seen in Minnesota. The infestation was noticed in September but he thinks the pests have been there for five or six years, based on the level of damage. Trees already have died. The known infestation is three miles long, reaching a bit to the west and into nearby Great River Bluffs State Park.
MnDOT's infested trees will be chipped and used in the area for erosion control and landscaping to help improve the health of other trees, said MnDOT forester Dan Gullickson.