Residents can pay to treat elm, ash trees

City can't cover cost to protect all its trees

April 4, 2012

Homeowners looking to protect their city-owned ash and elm trees from fatal pests and diseases can help offset the cost to the city by footing the bill for the chemicals used for treatment.

As part of its pest and disease prevention program, the Parks & Forestry Division treats a number of city trees for Dutch elm disease and emerald ash borer. However, because of the cost, not all city trees are receiving treatment. To ensure more trees are protected, homeowners can request to have their city-owned elm or ash tree treated for just the cost of the chemicals; the city will cover labor and equipment.

"Raising money for something like this, it's just not there because we can't raise the tax levy," Parks & Forestry Superintendent Ken Walbrandt said. "This is a more palpable way to deal with it. If we got a good response from residents, it would be a great program."

Dutch elm disease

The city has been treating for Dutch elm disease, a fatal fungus spread by bark beetles that affects American elm trees, for some 33 years with success. The city uses the fungicide Arbotect to treat the trees at the cost of $30 to $55 per tree.

Elm trees, which need treatment once a year, are most effectively treated in early June after the leaves have fully opened. This ensures that there is no wilt, which would indicate the tree is already diseased. If the tree shows signs that it has been infected, treatment can still be administered but at a different rate than what would be given to a healthy tree.

Emerald ash borer

Last year, the city began to treat ash trees for the emerald ash borer, a beetle native to Asia that attacks and kills all ash trees. The treatments, which need to be administered every two years, are a preventive measure after an infestation was identified in southern Milwaukee County.

"Right now we're treating 10 percent of the trees in Wauwatosa," Walbrandt said. "Ninety percent of the ash trees are unprotected."

The city is using Xytect insecticide to treat ash trees. The insecticide has commonly been used to treat birch trees for the bronze birch borer beetle, and has been shown to be effective against the emerald ash borer.

"I don't have a lot of firsthand data on this yet, but time will tell," Walbrandt said. "The statistics say this is effective. It has been used in Ohio and Illinois to effectively combat emerald ash borers."

However, its effectiveness only matters if the trees are being treated.

"The thing that concerns me most is that we aren't getting enough of them," he said. "It's not a guarantee; these treatments are not 100 percent. We could still lose trees, but leaving 90 percent of them totally unprotected is probably risky.

"It's going to be similar to Dutch elm disease," he said. "Trees not protected will for sure be killed within time."

The ash treatment cost depends on the size and number of trees being treated and can range from $12 to $30. The city administers the insecticide treatments in early spring and fall.

Residents can call at any time of year to be placed on the list for the next round of treatments, Walbrandt said.

For more information, contact the Department of Parks & Forestry at (414) 471-8420.


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