Gardeners, farmers and homeowners in Jefferson County call it an evil plant for a good reason.

Swallowwort is an invasive plant that, if left undisturbed, dominates everything else in the ground and multiplies exponentially — spreading from small, innocuous patches to consuming 5 acres in just a few years.

To learn about swallowwort and an array of other invasive plants and insects, a group of about 20 north country residents attended an information session hosted by the St. Lawrence-Eastern Lake Ontario Partnership for Regional Invasive Species Management on Thursday at the Cornell Cooperative Extension of Jefferson County office at 203 N. Hamilton St.

The goal of the nonprofit, which was launched last year, is to spread the word about noxious plants and pests and to prevent their spread in Jefferson, Lewis, St. Lawrence, Oswego and Oneida counties. Those who attended the presentation left armed with tips on how to detect the most pervasive invasive plants that have been giving environmentalists headaches for years.

Some of the most aggressive non-native plants in the north country are swallowwort, giant hogweed and Japanese knotweed and aquatic plants such as water chestnut and Eurasian water milfoil and hydrilla.

While experts shared a wealth of information about these plants, they were quick to point out that the average person doesn’t know what to look for. That’s why the first step is for municipal leaders and educators to get the word out to the public and to launch programs to combat the problem, said Robert K. Williams, invasive species program coordinator for the partnership.

Government programs can make only a small dent in curtailing the spread of invasive plants, but people who pitch in by reporting plant findings and forming volunteer groups to eliminate the plants can provide a major boost.

“The big thing is for the press and communities to come out and inform people,” Mr. Williams said. He said detecting plants in their early growth stage is crucial to preventing outbreaks.

Susan J. Gwise, horticulture educator for the county extension office, passed out samples from a 6-foot-long swallowwort plant for participants to examine. From a distance, the plants look fairly innocent, but a close-up look reveals small pods that look like beans.

When these pods burst in September and October, they distribute numerous seeds that multiply the plant’s life cycle. Each seed has a 10-year life span.

Holding up a plant for the audience to see, Mrs. Gwise demonstrated how the crown of the root needs to be pulled from the soil to prevent it from continuing to proliferate. Plants should be left in garbage bags to bake in the sun for a few hours to ensure they’re dead. Because of swallowwort’s ability to regrow every year, some homeowners have been fighting its spread for more than a decade with only marginal progress, she said.

Officials began fighting the problem in 2002, when the plants were found on hundreds of acres at Robert G. Wehle State Park in Henderson. The invasion has gotten increasingly worse, and swallowwort now is present countywide. Recently, the plants were spotted along the Black River Trail in Watertown.

“There’s nothing out there right now to combat it effectively,” Mrs. Gwise said. She said that herbicides don’t work well and that pulling the plants is the only viable solution.

The plant is unpleasant to animals, birds and insects and has no nutritional value. Its roots spread chemicals in the soil that prevent the growth of other plants, helping it to continue to spread.

A biological program launched about five years ago by the U.S. Department of Agriculture is seeking to find an insect from Europe to fight the spread of swallowwort, but the project is expected to take about two decades to achieve positive results.

Visit http://www.sleloinvasives.org to see examples of invasive species in the region. Those seeking to identify invasive plants are encouraged to take samples to the extension office.

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