To free urban forests from invaders, some weigh ban on noxious plants
English ivy and other invasive plants are strangling Seattle's forests, spurring a multimillion-dollar plan to restore the woods. It is also suddenly putting homeowners and garden stores here under scrutiny.
Experts, environmentalists and even some public officials are raising questions: Where's all this stuff coming from? Should it be outlawed?
Evidence of the weedy invaders is easy to find across the city, especially at this time of year. Maples on Queen Anne's western slope have dropped their leaves, exposing twisting cables of ivy that swarm up trunks and reach high into the trees' canopies, snapping tender branches.
In the greenbelt hugging Admiral Way Southwest, north of the West Seattle Bridge, dozens of trees are shrouded in ivy -- a chokehold that will tighten through the winter.
Many nurseries and big-box home-improvement stores in Seattle and across the state sell English ivy by the flat. The plant is intended for landscaping, but the fast-growing ground cover can be difficult to control.
"It's potentially very serious," said Sasha Shaw, an education specialist for the King County Noxious Weed Control Board. "It's really evident in the cities right now. That's where the plants are escaping more often."
Some people concerned about the health of urban forests believe it is time to ban the sale of the most aggressive invasive plants. Others think it's too late.
In 2002, Oregon put some forms of ivy on its quarantine list, banning their sale. In Washington, there are no controls. Ivy isn't even included on the state's list of most serious offenders, ranking among the least threatening of noxious weeds.
When ivy is spotted attacking trees in natural areas, such as on the fringes of Schmitz Park in West Seattle and Interlaken Park on Capitol Hill, it likely got there one of two ways: The plant either crept from neighboring yards into the woods, or birds ate the plants' berries and spread the seeds.
Ivy isn't the only non-native, ornamental plant to turn up in the woods. Others include English holly and laurel, and Himalayan blackberry, planted historically as crops.
"If we know something is a bad actor, nobody should be growing them," said Sarah Reichard of the University of Washington's Center for Urban Horticulture.
But state officials and some in the nursery business argue that the plants can be safely and responsibly grown -- if people are educated about the risks.
Besides, they say, ivy is so prevalent in our woods today that a ban would accomplish little. Instead, efforts should focus on increased education and volunteer efforts to pull the tenacious weeds.
"What would stopping ivy coming into this state accomplish at this point?" asked Mary Toohey, an assistant director and invasive weeds expert with the state Department of Agriculture. "It's loose. We need to deal with it in different ways."
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To free urban forests from invaders, some weigh ban on noxious plants
