New guide gives emerald ash borer treatment options
By Heather Thorstensen
hthorstensen@agrinews.com
Date Modified: 06/03/2010 9:21 AM
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ST. PAUL — Help is available for homeowners wondering what they can do to protect their ash trees from emerald ash borer.
The Minnesota Department of Agriculture, Minnesota Department of Natural Resources and University of Minnesota Extension created a four-page guide to help landowners decide if they should treat their trees with insecticide. It lists treatment options, gives recommendations on how to protect water quality while using treatments and provides tips on selecting, using and disposing of insecticide.
It only advises treatment on trees within approximately 15 miles of a known infestation. This range has been most effective. Minnesota's two 15-mile sites are the area encompassed by I-494 and I-694 in the Twin Cities as well as the very southeastern tip of the state in Houston County.
It's up to homeowners to decide if a high-value ash tree is worth trying to save, said Michael Schommer, communications director with the ag department. Treatment can cost tens of dollars to hundreds of dollars and will need to be made as frequently as twice a year to once every two years. Re-applications will be needed for an unknown number of years.
"It's a pretty good bet that it's a problem we'll be dealing with for many years," said Schommer.
It's Rochester city forester Jacob Ryg's opinion that people who treat outside the 15-mile range are throwing money away.
"You don't want to jump the gun because you're going to spend more money then you have to," he said.
An infested tree can still be saved with treatment if it has less than 30 percent dieback, he said.
The guide suggests all homeowners consider removing and replacing their ash trees in preparation for what seems to be an inevitable spread of emerald ash borer. Removal may cost less than repeated treatment, particularly on small or struggling trees.According to Ryg, the average fee to remove an ash tree with a 12-inch trunk diameter is $340.
Some communities, including Rochester, have already begun removing and replacing their ash trees. Rochester's removal efforts have been supported with money from the Outdoor Heritage Fund, part of the Clean Water, Land and Legacy amendment recently added to the state constitution. The state agriculture departmentadministered $1.875 million earlier this year in grants from the fund to help local governments and other organizations respond to infestations as well as to help other areas prepare.
Homeowners who want to use treatment should evaluate their options with a certified arborist or city forester, the guide says. They should check if their city or township has restrictions against treatment, which could apply to trees planted near boulevards or sidewalks. Large trees should be treated professionally. The guide suggests hiring someone licensed in Minnesota as a commercial pesticide applicator for category E, which covers turf and ornamentals.
It's best if treatment is applied betweenmid-April and the end of June so insecticide reaches leaves by the time adult beetles emerge to feed in early June.
The most important thing people living outside infestation areas can do is keep an eye on their ash trees for the pest and not transport products, such as firewood, that may carry emerald ash borer, Schommer said. Quarantines restrict the movement of ash products, such as firewood or woodchips, in Ramsey, Hennepin and Houston counties.
"It's important for people to get out of the habit of moving firewood," Schommer said. "It's also important for people on their own property to be thinking of how to deal with this."
Signs of emerald ash borer include woodpecker activity, bark splitting or dieback at the crown of the tree.
Emerald ash borer is an invasive insect first found in Minnesota in May 2009 in St. Paul. It's expected to impact not only communities and homeowners, but also the environment by feeding on and killing ash trees. Minnesota has an estimated 900 million ash trees. Between 3,000 to 3,500 purple traps will be set up around the state this year for monitoring purposes.