Ham Lake's tree inspections stir up strong feelings

Residents of Ham Lake, 36 square miles of quiet in the middle of Anoka County, like their privacy. The city even has a one-acre lot minimum to ensure that neighbors don't get too close to one another.

So some residents didn't take kindly to it when a city tree inspector walked onto private property last year and used paint to mark more than 700 trees for suspected oak wilt. Failure to remove trees deemed diseased resulted in a fine.

The policy was more than 10 years old, but it got heightened attention because the number of oaks marked as diseased in 2013 rose by nearly 40 percent over the previous year.

Despite protests from the city's tree and park commission that unchecked oak wilt could destroy the canopy, the City Council replaced its tree policy, which had included mandatory inspection and removal, with a voluntary one. Now the city tree inspector can examine trees only from nearby public property, like a road, and removal of diseased trees is voluntary.

The tree debate is the thorniest issue to arise in Ham Lake in recent years, pitting property rights vs. the health of the forest.

Ham Lake Mayor Mike Van Kirk defends the policy. "Ham Lakers are responsible people," he said. "We are not children."

He and council members said they have faith that residents will take care of their problem trees, and suggested that some trees might have been misdiagnosed.

At a recent council meeting, Van Kirk had harsh words for the former policy, describing it as a "mandatory, jackbooted, stomp-on-your-property issue.

"That is the part this council is not going to stomach," Van Kirk said.

The mayor also questioned the effectiveness of removing diseased trees, saying it could constitute a losing battle against Mother Nature. "This is analogous, to me, to trying to stop the common cold by shooting everybody in the head that is infected with the cold virus," he said.

Ham Lake City Council Member Al Parranto, who also supported the policy change, said, "The citizens are responsible and interested in maintaining their tree coverage without the force of government.

"Being a father of two daughters, I don't like anyone uninvited in my yard," he said. "I understand the police and firefighters in my yard. The arborist was the other person on that list. It didn't seem right."

The science of oak wilt

But members of the city tree and park commission and tree experts say the new policy is a bad idea.

Each year, oak wilt kills large numbers of oaks in Minnesota, with infections concentrated in the southeastern part of the state, including the Twin Cities. The disease is caused by a fungus that spreads through root systems, or is sometimes transmitted by beetles.

Because diseased trees can spread the fungus to neighboring oaks, experts advise removing dead and diseased trees and severing root connections.

"Oak wilt knows no political boundaries. It knows no property lines," said Gary Johnson, a professor of urban forestry with University of Minnesota Extension who holds a graduate degree in tree pathology. "If there isn't a program to keep that oak forest healthy, you could end up with half the trees or no trees if the disease runs rampant.

"I do realize it's political," he said of the Ham Lake dispute. "I love southeastern Minnesota because oaks dominate our forest. I think we should be doing everything we can to preserve that character in Minnesota."

Johnson said 700 trees with oak wilt in a city of Ham Lake's size is not an unreasonable diagnosis.

Foresters and inspectors diagnose oak wilt after a visual inspection. To confirm the diagnosis, the Plant Disease Clinic at the University of Minnesota will test a limb for $59. Last year, the lab tested about 100 samples.

"A majority of the time we get suspected samples, they do turn out to be positive," said Brett Arenz, a faculty member in the University of Minnesota's Department of Plant Pathology and director of the plant disease clinic.

Summer is the optimal time to test for the disease if infection is suspected, he said. Testing becomes more difficult in the autumn, when the fungus becomes dormant.

'A little disappointing'

Mel Aanerud, chairman of Ham Lake's tree and park commission, helped craft some of the city's original policies to manage oak wilt more than 20 years ago. "We had the second-worst infestation in the state 20 years ago," he said. "We had 9.7 infestations per square mile. We got it down to one infestation per square mile."

Aanerud said the City Council's defense of property rights was too narrow.

"We have to deal with everybody's property right," he said. "I predict we will see an increase in oak wilt in the city. Some point, five to 10 years from now, people will ask why we didn't keep doing what we were doing. It has worked."

In neighboring Blaine, City Forester Marc Shippee called the Ham Lake policy change a shocker.

"Ham Lake was the most vigilant on oak wilt, even more than Blaine," he said. "This is almost a 180 from what they have been doing. It's a little disappointing. It affects our efforts here to control it if they are not requiring infected trees to be removed."

Blaine inspects and marks diseased trees, and property owners are required to remove them. The city targets about 300 oaks a year for removal.

Shippee said he does most of his work from the street or on a complaint basis. "We don't go crawling through people's wooded acreage. If we get a call or see it from the street, we will inspect," he said.

Aanerud, of Ham Lake, already has lost one tree to oak wilt, and worries it won't be the last. "The kids had their treehouse in that tree," he said. "It was really too bad."

Shannon Prather • 612-673-4804