Farewell to the Norway maple

All along 1300 East, the once-green leaves of the tall Norway maple trees are turning paper-bag brown, and officials say the trees are simply the wrong kind for the area — too tall and too thirsty to survive in the city.

City forester Bill Rutherford said many of the trees have been directionally pruned to make way for power lines that run above and through the foliage. And while Rutherford said such pruning is necessary, it creates more problems for the trees than just a disfigured shape.

"They have to be pruned to so power companies can provide a safe service to their customers," he said. "But as a result, the tree is exposed to more solar radiation."

The Norway maple likes to "keep its feet wet" and prefers more mild conditions, Rutherford said. The tree's canopy keeps it cool and extensive pruning is hurting the trees, he said.

"They're just like you and I," he said. "We like the shade, and these trees need that kind of shade and shelter, too."

The concrete forest these maples are trying to thrive in is another problem, Rutherford said.

"There's a whole lot of heat in the asphalt, concrete and steel around the trees. It radiates back into the canopy, and if there's not a tremendous amount of irrigation, the leaves appear paper-bag brown instead of vibrant green."

Rutherford said water-saving campaigns like Slow the Flow have been effective in persuading people to conserve water, but said water conservation doesn't bode well for the Norway maples.

The trees are facing other serious problems, Rutherford said. Petroleum residue from passing vehicles and de-icing salts during the winter contaminate the soil and kill the trees' roots. Additionally, many of the trees suffer from a disease called verticillium wilt. The disease is caused by a soil-borne fungus that causes leaf scorch (a marginal browning of the leaves), slowing tree growth, heavy seed crops and wilting of shoots and branches. Often, the foliage on the tree's branches will wilt suddenly. Other symptoms of the disease include leaf drying, curling and abnormal red or yellow leaves.

"It's like the hardening of arteries in human beings," he said. "The trees become less efficient at moving soil."

In the end, the only viable solution is to replace the Norway maples with different trees, Rutherford said.