June 6, 2005

By Reni Winter
(Lafayette) Journal and Courier

WEST LAFAYETTE, Ind. -- It takes a tough tree with a rugged root system to survive in an urban environment.

Add the invasion of a natural pest to the built-in challenges of automobile exhaust, concrete-induced root stress and periodic bark damage from lawn mowers and weed trimmers, and the difficulty of growing trees in an urban environment multiplies rapidly.

Purdue University researchers at the Hardwood Tree Improvement and Regeneration Center in West Lafayette have joined a national trial to produce a superior tree for city streets.

Purdue entomology professor Cliff Sadof and Purdue forester Brian Beheler planted 14 varieties of elm trees recently at the university's horticulture farm on Sharon Chapel Road at the start of a study to determine which variety is the most promising to replace the ash as an urban street tree.

The project was developed in response to a recent invasion of the emerald ash borer, which threatens a popular urban street tree, the ash, center director Charles Michler said. "We are working with elm hybrids to replace the ash as an urban street tree."

The entire set of elms will be replicated at 15 sites in 14 states, Sadof said.

It's a 10-year study, but thinking in terms of decades, even centuries, is part and parcel of forestry -- urban or rural.

"It's very difficult for trees to survive in urban areas," said Belinda Kiger, Lafayette's manager of community parks and urban forestry. "Some of these large oaks that are 100 years old, we won't have trees like those in the future. They started growing long before we had pavement, sidewalks, air pollution, ground pollution."

The first few years of a tree's life will play a large part in determining the tree's overall health, longevity and size.

"We have to plant now for the future," Kiger said. "If everyone had the attitude not to look to the future, it's possible we wouldn't have many trees."

Longtime West Lafayette resident Helen Lillich, a member of the West Lafayette Tree Fund, is credited with planting hundreds of trees in the city. She said she never tires of planting and caring for trees.

"They're so beautiful, so aesthetic," she said. "They cool us; the leaves make noises in the wind. They take in carbon dioxide and let out oxygen, and we certainly need that. I really like the old, wide streets with the large trees. I really wish streets were still like that."

The emerald ash borer may or may not come to Central Indiana, but the worst threat to trees is already here -- humans, said Bev Shaw, West Lafayette's greenspace administrator.

"Hitting them with mowers and weed trimmers, parking over the root system -- it's incredible the number of trees that get hit by lawn mowers and weed trimmers," she said. "Damage to the bark can kill a tree."

Ignorance about what trees need is also a threat. Over-mulching or improper mulching is another common problem.

Although research is pointing toward new tree hybrids as well as revised methods of planting and maintaining trees, the size of the hole recommended for tree planting hasn't changed at all, said Jeff Freel, certified arborist with Bellinger's Professional Ground Maintenance near Shadeland.

"The old standard is twice as wide as the root ball," he said.

West Lafayette is surveying all of the city's trees, thanks in part to a grant from the Indiana Department of Natural Resources, Shaw said.

"We'll be able to tell where there are too many ash in one area, and then we can go in and plant other trees, so that in case we get hit with the ash borer, we won't have large areas with no trees."

Distributed by The Associated Press.