Seattle Faces a Foe That’s Mean, Green and Growing

For the last three years, Chris LaPointe has waged war against an enemy that he believes threatens much of the Pacific Northwest, and he has recruited an army to join his side. He needs all the help he can get.

The enemy is almost supernaturally hardy: It resists poisons, can withstand extreme temperatures and can survive most efforts at cutting it to pieces.

The enemy is English ivy, a nonnative leafy vine that scientists say threatens entire forests in Washington, Oregon and British Columbia. The ivy grows and spreads so fast that it overwhelms native plants, strangles trees and shrubs, and -- if it isn’t stopped -- can turn a forest into an “ivy desert.”

“I know what this plant can do,” says LaPointe, an organizer for EarthCorps, a nonprofit conservation group in Seattle.

Since 2002, LaPointe has helped rally thousands of volunteers to remove English ivy from one of the city’s most popular hangouts, Seward Park. His work parties, sometimes as large as 300 people, this year have removed about 114,000 square feet of ivy, which had devoured a large swath of the park.

It is hard work that entails pulling up the roots by hand. Thick vines are cut by saws or shears. Any cutting above the roots often results in the plant growing back. LaPointe says it can take five hours for a crew to clear an acre.

English ivy does not grow nearly as fast as kudzu, the infamously aggressive perennial vine that blankets much of the South. Kudzu grows as much as a foot a day at the height of summer and has a much thicker root structure than English ivy, but over time the effect on native vegetation is much the same.

In Seattle, where as much as 55% of the city’s forestlands are infested with English ivy, the mayor has warned that “we’re at risk of becoming the city ‘formerly known as Emerald.’ ”

Officials estimate that clearing the urban forests of ivy and other nonnative plants, and restoring the land could cost as much as $20,000 per acre, which would amount to a hefty bill to tackle just the 2,500 acres deemed most at risk. But the alternative isn’t pretty.

“Thirty years from now, there won’t be any forest left [in the city] if we don’t do something about it,” says Mark Mead, a forester with the Seattle Parks and Recreation Department.

English ivy, also known as Hedera helix, is an evergreen vine with green pointed leaves marked with white veins. If allowed to mature, the vine produces white-green flowers in the fall. In the spring, the flowers bear fruit, which is spread by birds.

The ivy is native to Europe, western Asia and North Africa, and is believed to have come to the United States with European immigrants. For decades it was popular as a landscaping plant, and many gardeners and landscapers still use it for that purpose.

“This ivy used to be regarded as a great landscape solution” because of its fast growth and even coverage, says Jeanne McNeil, executive director of the Washington State Nursery and Landscape Assn. “It still can be, if it is kept contained, and not allowed to mature.”

The Oregon Department of Agriculture placed four types of H. helix on the state’s quarantine list in 2002, banning their sale and importation.

“There was a lot of concern about the damage the ivy was doing, particularly out of the Portland metro area,” says Tim Butler, manager of the department’s noxious weed program. He says the quarantine has been effective.

In Washington, English ivy is classified as a class-C noxious weed, which means that individual counties may take steps to eradicate the plant. But state officials have been resistant to the idea of quarantine.

Mary Toohey, assistant director of the state Agriculture Department, says that such a measure would have little effect.

Toohey says educating the public is the best way to combat the spread of English ivy. In addition, she says, volunteer groups such as EarthCorps have been effective in clearing areas of the plant.

The Washington State Native Plant Society maintains a list of ivy-free Nurseries as part of its Ivy Out campaign, and this year the Washington State Nursery and Landscape Assn. started a program asking some members to stop selling H. helix and to educate people on alternatives.

One nursery that had no problem joining the effort was Swanson’s Nursery, which has been operating in Seattle for 82 years.

“We had actually already stopped selling the invasive ivy cultivars a few years back,” says Gordon White, a buyer for Swanson’s. White says an increasing number of people in Seattle are becoming aware of the problem.

Mead, the Seattle forester, calls English ivy a “gateway plant.”

“English ivy isn’t the whole story,” Mead says. “We have to get the other ‘invasives’ out as well and restore the forests. But the ivy gives us a focus to get people involved, and that’s how we’ll solve the problem.”

Federal agencies spend about $1 billion a year on the management of invasive species, according to a federal report issued this year. The report, from the Government Accountability Office, calls the spread of invasive species “an explosion in slow motion” with weeds now covering an estimated 133 million acres nationwide.

There are no overall federal controls for invasive weeds. States are left on their own to classify and deal with such plants, and there is little uniformity in the regulations.

Horticulture groups say English ivy has spread to at least 26 states, including California, but the plant has not been recognized as threatening in all of those areas. California lists 236 plants as noxious; H. helix is not one of them.

Back in Seattle’s Seward Park, LaPointe, the EarthCorps organizer, says that when his volunteer groups started working in the park in 2002, the goal was to be rid of the ivy by the end of 2003.

Here it is, almost 2006, he says, and “we’re still working on it.”