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Battle against noxious weed invasion rages on

Garlic mustard continues to gain a foothold in the gorge
by: Carole Archer, Julie DiLeone, left, and Lynn Gibbons pull and bag garlic mustard near the Columbia Scenic Highway on Monday, April 23. The invasive weed grows throughout the gorge, destroying native flowers such as purple Delphinium, trillium and snowberry.

In May, when the garlic mustard blooms, Lynn Gibbons worries that he is losing the war.

Two years ago, Gibbons was among the first to alert Corbett-area residents to the noxious and invasive garlic mustard spreading in the Columbia River Gorge. Since then, he has found allies in the fight, but the weed is still winning.

'It has reached the city limits of Troutdale,' says Gibbons, who works in maintenance at Menucha Retreat and Conference Center in Corbett.

And it has begun to reach state and federal agencies. Julie DiLeone of the East Multnomah Soil and Water Conservation District admitted, 'At first I thought it was just another weed. And then I realized how wrong I was. When I saw it, my heart sank a little bit.'

Somehow, maybe from seeds on a hiker's boot, garlic mustard moved from the eastern states to gain a foothold in the woodlands between Crown Point and Corbett. Gibbons began to panic when he saw how fast the invader moved, knocking out trilliums, ferns, even the pervasive nettle. Garlic mustard is allelopathic, meaning it excretes a chemical from its roots that is toxic to other plants.

What's left is a monoculture of garlic mustard, acres of it, poisoning and stifling trees and plants and, eventually, the creatures that live there. Worse, its seeds last five years. Because it blooms biennially, it fools people by disappearing for a year and then coming back.

It travels on cars, boots and animals and down streambeds and game trails. This year, the invader began to descend the basalt cliffs of the gorge, where nothing can reach it. Gibbons, driving through Corbett this season, sees it blooming on nearly every roadside.

'I remember the first time I saw it,' says Debbie Lowry, Latourell homeowner and gardener. 'A plant with a white flower about 2 and half feet tall on both sides of the roadway.'

A week later at the annual plant sale of the Columbian Garden Club, Gibbons sounded the alarm.

'Now, all of sudden you blink and here are the plants everywhere,' Lowry says. She and her husband, Richard, have managed to keep it down on their acre of land, but both roads into Latourell are lined with the weed, and she is trying to rally neighbors to help fight it. On the historic highway, Bridal Veil residents Steve and Judy Lehl will spend her birthday, May Day, pulling and bagging garlic mustard. They have worked on that stretch of the highway for the last two years.

'It's very frustrating because we are trying to approach it from all avenues, but the government agencies are talking about mapping and wondering about herbicide, and it's hard to get everybody on the same page,' says Lowry.

Lehl is horrified at the inaction.

'The county should be out here knocking on every door and telling property owners to get rid of it,' he says.

DiLeone, whose agency is non-regulatory, says Multnomah County, the Oregon Department of Transportation and Oregon State Parks are working on plans to control the weed.

Sensitive to environmental issues in the gorge, Multnomah County elected to mow roadsides instead of spraying with herbicide, DiLeone said. But occasional mowing only makes garlic mustard happier. Mow it in the spring, and it sends up new growth and still manages to bloom. Mow it in late summer, and it spreads thousands of seeds.

The best way so far, Gibbons says, is to hand-pull it, making sure to get the root, then bag the weeds as you would toxic waste and send it to a landfill. Left to its own devices, garlic mustard will bloom uprooted in a black plastic bag.

'The only good thing is that it's easy to pull up,' says Gibbons. But the next year, a rosette of new growth, sprouting from seed that survives as long as five years, starts the biennial cycle all over again. Some homeowners have had success by pulling the flowering plants and spraying the rosettes of first-year growth with herbicide.

'I finally broke down and used herbicide,' says Lowry. 'We're careful, and we just use a spot sprayer to hit the individual plants.'

DiLeone says there is some good news. The East Multnomah Soil and Water conservation district sent out 2,000 color brochures to help homeowners identify and control the garlic mustard.

Cornell University, she says, is looking for a biological control, a bug, for instance, that might eradicate garlic mustard without causing problems with native plants.

And, adds DiLeone, though garlic mustard is on the state noxious weed list and illegal to grow, it is edible and was likely brought to the United States from Europe as a salad green.

'I suppose there is a chance that pickers might wild-craft it and sell it to restaurants,' she mused.