Experts doubt success of Sebastopol's weed planFriday, March 4, 2005
By Carol Benfell, The Press DemocratSebastopol's decision this week to allow volunteers to clear two acres of noxious weeds by hand is a plan that will require years of hard labor and one that never has succeeded in other Western states.
Sebastopol is betting the future of Laguna Park, part of a rich wetland ecosystem that is home to dozens of native plants and wildlife, on its ability to remove pepperweed, one of the worst and wiliest weeds in the West.
"If it's going to work, they have to do it over and over and over again for years and multiple times a year," said Joe DiTomaso, an invasive weed specialist for the UC Davis Cooperative Extension.
"If they have the patience to do that, they may (succeed), but I've never seen it work," he said.
If Sebastopol loses its gamble, the delay in using herbicides could allow the weed to spread, requiring more spraying of larger areas of Laguna de Santa Rosa with less chance of overall success.
Perennial pepperweed, a native of Europe and Asia, is a tall, spindly white-flowered plant that has spread throughout the West in the past 20 years.
The plant is growing in patches and clumps on 12 acres along the laguna between Guerneville and Stony Point roads. Owners of 10 of the acres will use herbicides that are sprayed on the leaves and work down through the veins to kill the roots.
But on Tuesday, the Sebastopol City Council, one of the few in the nation with a Green Party majority, decided to organize volunteers and try hand-pulling on the city's two acres.
The nonprofit Laguna Foundation, which is seeking to restore the laguna, has given its blessing and will help pay for a volunteer coordinator.
Anna Sears, the foundation's research director, acknowledged that hand pulling pepperweed has not worked well, but said Sebastopol may have unique advantages.
Laguna Park is readily accessible by foot, pepperweed is in the early stages of establishing itself and a large number of people have come forward to do the work, Sears said.
"Perhaps hand removals have been ineffective in other areas because no one has been willing to take on the sustained effort it is going to require," Sears said.
Volunteers will use a variety of strategies to attack the above-ground part of the pepperweed, but they won't go after the deep, branched roots, Sears said.
"To dig up roots would destroy the whole park. The strategy is to starve the roots by depriving them of light by mulching or by bringing in sheep to graze," Sears said.
The city will closely monitor the work and quickly switch to herbicides if hand methods aren't working, Mayor Larry Robinson said.
"I don't think any of us is under any illusions of what's at risk," he said. "But I think we're also aware that we have the chemical solution as a backup, if it becomes apparent we're failing."
Thirty-six people have signed up to work on the pepperweed, but more volunteers are needed along with donations of cash and tools, Councilman Craig Litwin said. Volunteers will meet Thursday to organize and map out strategies, and the first work party would go out within a month, he said.
"My hope is we can crack the code on how to deal with pepperweed with physical labor. This is our chance to show that people power can restore the land," Litwin said."
Those who have worked to control pepperweed wish Sebastopol well but don't hold out much hope.
In a situation that parallels the laguna, Vashon Park District near Seattle has used volunteers for three years to hand remove pepperweed growing on about two acres of park land.
This spring, the park district will switch to herbicides, said Sean Hawley, the district's maintenance supervisor.
"We've tried cutting and digging for three years, and I really can't say I've achieved any real success," Hawley said. "It's still there and it's still coming back. The plants may not be as big, but they're still there."
Elsewhere in Seattle, volunteers with People for Puget Sound, an environmental group, have had some success after three years of removing pepperweed by hand from about an acre along the Duwamish River.
"We've had 10 to 15 volunteers at a time and done one pass at each site per year, and we have seen some reduction in the amount of pepperweed coming back," said Sean MacDougall, an invasive weed specialist with the noxious weed control program for King County, Wash.
But the soil along the Duwamish River is sandy -- not like the hard-packed earth along the laguna -- and it's easy to pull out large one- and two-foot lengths of root, MacDougall said.
He doubted the effort would have had even limited success if the roots had been left in the ground.
"If you leave any of that root system in the ground it's going to find a way to produce new roots and it's going to continue," MacDougall said.
In Reno, officials tried mechanical removal. They disked fields of pepperweed every month from May to August, removing every fragment of plant and root they found.
"It came back the fourth year and it was 100 percent cover, the same as when it started," DiTomaso said. "They didn't get rid of it at all."
The Yolo County Resource Conservation District reported that even herbicides must be carefully and thoroughly applied.
"Even with herbicide applications, stands may regenerate from creeping rhizomes (roots)," a report said. Researchers estimated that "even with 98 percent control, resprouting plants in the spring would result in total stand dominance by the end of the growing season."
You can reach Staff Writer Carol Benfell at 521-5259 or cbenfell@pressdemocrat.com.
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