Foreign plants can appeal to the eye, but sometimes these non-native species can cause great damage to their new environment.
Ailanthus altissima, a dense, fast-growing tree that comes from China, is threatening different plants and trees in Central Pennsylvania. Penn State is working with the Pennsylvania Department of Transportation to combat this foreign invader.
Route 22/322 between the Millerstown and Amity Hall exits is the first place that ailanthus is being attacked.
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"Farmers are dealing with a weed that they never had to deal with
before. . . . In one field I was at, there was 10 ailanthus for one Christmas tree." — Larry Kuhns
professor of ornamental horticulture |
Art Gover, horticulture research support associate and part of the joint venture, said of ailanthus, "It's very tolerant of poor soils and air pollution, which means it's well suited for disturbed sites, like road sides."
Jon Johnson, horticulture research support associate and member of the team, said, "It colonizes an area as it gets bigger."
The problem with ailanthus along roadsides is that it is a weak limbed tree, and it has a propensity of falling into the road and hitting cars or interrupting traffic.
The process to combat this Chinese tree infesting the highway is very involved. First, a high volume foliar herbicide is applied to the growth.
Ailanthus grows in a circular pattern, and it is difficult to get to the center, which contains the oldest trees. To kill the brush, herbicide is sprayed out from a gun to hit the ailanthus.
But these trees can grow very tall, sometimes as high as 60 feet, and only the initial growth is affected.
The second part of this plan is to use a basal bark solution to attack the trees not hit by the first wave of herbicide.
"(Basal bark) is very selective. You apply an oil based solution to the lower 12 to 18 inches of the trees," Gover said. "It's very laborious."
"The key to managing this species is to control its root system and the only way to get the herbicide into the root system is to apply it in the active growing (season)," he said.
The season is about three to four months long. It begins in late June and it ends during the middle stages of the fall.
Ailanthus cannot be cut down because if it is, it grows back violently and quickly.
"It's very easy to make it worse," Gover said.
After this first phase is completed, which should be the summer of 2003, the management phase of the process will begin. A low volume foliar herbicide will be used to kill any new sprouts; it has to be applied annually.
Different industries are also trying to cope with this new invader.
Ailanthus is also affecting farmers. It damages and clogs corn-picking equipment. The ailanthus grows back so quickly after being cut that it only causes a larger problem the next year.
"Farmers are dealing with a weed that they never had to deal with before," said Larry Kuhns, professor of ornamental horticulture.
Ailanthus also is affecting Christmas tree growers.
"In one field I was at, there was 10 ailanthus for one Christmas tree," Kuhns said.
Kuhns said species such as ailanthus pose a grave danger in the future.
"I feel that invasive exotic plants are going to be the biggest environmental problem in this century," Kuhns said.
"Things like air pollution, abandoned strip mines, and the hazardous waste . . . sites, which were big problems in the '60s, and '70s could be cleaned up in 20 years. The invasive plants just keep spreading and spreading and they're almost impossible to eradicate."
