Sherburne to assist city in preparing for emerald ash borer

The Sherburne County Soil and Water Conservation District (SWCD) office will be leading an initiative this year called the Urban Forestry Program that could help Princeton and the other cities in Sherburne County prepare for a possible invasion of the destructive emerald ash borer (EAB).ash-borer-hugo
Photo by Joel Stottrup
Sherburne County Soil & Water Conservation District Director Gina Hugo addresses the Princeton City Council about Sherburne’s plan to deal proactively with the possible invasion of the emerald ash borer into the county and Princeton.

The EAB was discovered in Michigan and Ontario in 2002, and since then it has destroyed more than 50 million ash trees in the United States, according to the New York State Department of Conservation. The EAB has spread west to where it was even discovered in the Twin Cities metro area.

Sherburne SWCD Director Gina Hugo presented her Urban Forestry Program with the EAB component to the Princeton City Council last Thursday. At one point, she passed around a small vial containing a dead adult EAB with its distinctive emerald color.

The city of Princeton has a small portion inside Sherburne’s boundaries, but Hugo noted that the initiative will also include the rest of the city which lies in Mille Lacs County. Her SWCD office will be working with the University of Minnesota, the St. Cloud State University Research Center, and the Minnesota Department of Natural Resources in the program.

Hugo, in a presentation to the Princeton council, showed a map with major highways leading from the metro area on north. She explained that those are potential routes for the EAB to move into the Princeton area.

If the EAB comes to Princeton it would likely be aboard ash firewood hauled in from a source that was infected by the EAB, Hugo said. The EAB, which in the adult stage ranges 3/8-5/8 inches long, kills ash trees through its larvae burrowing through the bark into the vascular system. The burrowing severs the flow of nutrients for the tree, which can then die within 2-4 years.

Minnesota has about a billion ash trees and Hugo suggested that governments be proactive rather than reactive about the threat of the EAB.

Former Princeton Community Development Director Jay Blake had talked to the council and the city’s public works department about four years ago regarding the EAB and the idea of removing some ash trees in stages in advance of a possible EAB invasion.

But the city never went beyond the talking stage with the idea, perhaps because the EAB hasn’t yet surfaced in Princeton. Hugo’s plan is for Sherburne to begin acting by first inventorying Sherburne’s urban trees.

Volunteers needed

Hugo noted that the plan would need volunteers to help with the inventorying starting this coming spring and winding up by August. The inventorying would be done using a combination of counting all trees within so many blocks and then estimating the rest, a method that Hugo says is accurate within 10 percent. Hugo urges anyone interested in volunteering to call her at 763-241-1170, ext. 3.

The inventory would then be given to the city council and the city could then work on a preparedness plan in the event of an invasion of the EAB. It would include identifying the resources the city could use, the costs and the plan of attack. It could mean cutting down ash trees and saving a certain number of ash considered of high value, using an annual chemical treatment. That treatment would have to continue for the life of the ash tree, Hugo said, calling it like “putting the tree on life support.” There is no known biological control of the EAB, Hugo added. She did mention, in an interview later, the Animal and Plant Health Inspection Service within the U.S. Department of Agriculture researching to see if a stingless parasitic wasp could be a way to attack the EAB.

Hugo also noted that a tree-growing bed has been established in Becker to provide healthy trees of species other than ash to transplant into cities in Sherburne. Among the desirable trees to plant, according to Hugo, are paper birch, black cherry, hackberry, bitternut hickory and little leaf linden.

The trees coming out of the Becker nursery bed would have a better chance of surviving than some trees where nursery workers place the roots in burlap balls, she said. Sometimes the roots inside the burlap will circle around and girdle and kill the young tree, she explained.

Hugo said she expects that Sherburne’s Urban Forestry Program will result in the planting of as many as eight of the young trees in the city of Princeton this year.

The Urban Forestry Program will have an urban forestry committee made up of representatives from city staffs in the cities of St. Cloud, Becker, Big Lake, Elk River, Zimmerman, and Princeton to set the program’s goals.

Mille Lacs County SWCD Conservation Technician Lynn Carter was reached on Monday to see what her department is doing about any EAB threat. Carter said her office has been working on keeping track of any EAB infestations in the county, including Princeton. So far her department has not found any evidence of an EAB presence in this area, Carter said.

Carter added that in light of the seriousness of the EAB invasion across much of the United States, the Mille Lacs SWCD no longer offers ash trees in its annual program of selling tree and bush seedlings to residents.

Hugo noted that an EAB invasion could take place “any day,” and mentioned the quarantine in effect in Hennepin County regarding ash trees.

Actually both Hennepin and Ramsey Counties have this quarantine and it means that it is illegal under the quarantine to move the following out of those two counties: firewood from any hardwood species, including parts or the entireties of ash trees, or any ash logs or untreated ash lumber with the bark attached. It is also prohibited to transport uncomposted ash chips and uncomposted ash bark chops larger than one inch in diameter, or the emerald ash borer in any living stage of development out of Hennepin and Ramsey counties.

The Minnesota Department of Agriculture and the University of Minnesota Extension has information on identifying ash trees, how to tell the EAB apart from other insects, and suggestions on what a property owner should do if they have an infected ash tree.