Emerald ash borer poses danger to nearly half of Morris' city trees
MORRIS - The Morris area is full of healthy, well-maintained trees, but the looming threat of emerald ash borer presents a danger to nearly half of the trees on city property and almost a quarter of the trees on private land.
Gary Johnson, professor of urban and community forestry with the University of Minnesota Department of Forest Resources, presented these results from an volunteer-driven study of Morris' trees to Morris City Council at their meeting Tuesday.
A primary focus of the study was to assess how vulnerable Morris' trees - about 8,800 that are privately owned and 2,500 on city property - would be to emerald ash borer.
Across the community, about 27 percent of the trees in Morris are ash trees. On private land, around 22 percent are ash, while the statistic for the city-owned trees is "a little bit grimmer," said Johnson. About 46 percent of the city's trees - many in Pomme de Terre Park - are vulnerable to EAB.
Johnson did have good news about Morris' trees. The average size for the most common types of trees was about a 14.5 inch diameter, which can indicate a tree of between 30 and 80 years old, depending on the species. And on average, the overall quality of Morris' trees is good, said Johnson.
Another measure from the study was "relative crown spread" - the area that Morris' most common trees cover. In total, around 140 acres of the Morris area is covered by this canopy. However, if cover provided by the ash trees is eliminated, the city would lose about 30 percent of the canopy. Take away the ash and maple trees, and more than 50 percent of the canopy would be gone, said Johnson.
"We do know that emerald ash borer is in Minnesota," said Johnson. "Emerald ash borer loves ash trees, and it's probably a matter of time before it gets here because Morris is a place people come for vacation. ... You have parks, you have rivers, you have lakes and unfortunately people bring firewood with them. That's how emerald ash borer spreads."
Another insect within "striking distance" of Minnesota is the asian longhorn beetle, which poses a threat to maple trees.
Given this information, Johnson told the council that it would be important to have a management plan moving forward to decide which trees the city might try to save, which might be sacrificed and what types of new trees will be planted in the area.
Chemical treatments that protect against emerald ash borer are becoming less expensive, but "generally speaking, it's not a wise thing to throw good money at bad trees, but you have some really good trees in the community," said Johnson.
"If you decide one of your tactics will be chemical controls, you have some trees that are worthy of it," he said.
So far this summer, city crews have been busy planting trees downtown as part of a $25,000 Department of Natural Resources Minnesota Community Forest Bonding Grant that was procured by City Inspecting Engineer Jay Fier and the Morris Tree Board.
City Manager Blaine Hill told the council that the downtown planting is "not an easy issue" and that he has had numerous conversations with downtown business owners about the new trees, which they worry will block their signs.