May 17, 2011

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Every year, invasive plants cause $137 billion in economic losses in the United States.

“This is a serious battle, and everyone needs to engage,” said Songlin Fei, forestry assistant professor in the University of Kentucky College of Agriculture , referring to the ongoing war against exotic invasive plant and insect species.

Recently, Fei and fellow university researchers, natural resource managers and landowners gathered in Lexington for a joint meeting of the 2nd Kentucky Invasive Species Conference and the 13th Annual Southeast Exotic Pest Plant Council Conference. The three-day meeting covered research, management, outreach, education and policy topics for the central and eastern regions of the country.

Due to chemical regulations and environmental acts that have been in place as early as the 1950s, Fei believes most people understand the importance of environmental protections.

“What they do not see is that the biological protections are important to protect our native species and ecosystems that are precious,” he said. “People have planted in their minds, because of the environmental protection movement, that green is good. But they don’t realize that not all green is good.”

To Fei and the other conference participants, invasive exotic plants such as bush honeysuckle fall into the “not all green is good” category.

“It’s very important (for the average person to learn about invasive species), because it’s pretty much in everybody’s backyards,” said Beverly James, preserve manager at Floracliff Nature Sanctuary in Fayette County and a member of the conference planning committee.

Everyone’s backyards are, in a sense, “upstream from these natural areas,” she said. With birds, water and wind easily transporting seeds throughout the ecosystem, “what people grow in their backyards has a big effect on natural areas.”

Many of the invasive plants found in Kentucky were brought in years ago as landscape plants. Lonicera maackii, bush honeysuckle, was imported from Asia in the late 19th century for such a use. Unfortunately, when a species is released into a novel habitat, there is often no regulation by natural enemies. The result is increased abundance, vigor and distribution. Homeowners spend money and time trying to eradicate invasives such as wintercreeper, multiflora rose, English ivy and Virginia creeper, to name only a few. Woodland owners fight a continuous battle to rid the understory of honeysuckle, and burning bush can take over open grasslands.

Bush honeysuckle is endangered in its native Japan, but it is a dominant element in Kentucky, Ohio and Indiana forests. During the conference, Wright State University’s Deah  Lieurance, who is researching herbivore damage to the plant, indicated that despite 81 species of caterpillars who could feed on honeysuckle, the amount of damage to the plants is negligible.

“It indicates there is an escape from natural enemies,” she said during her presentation. “They have so many weapons in their arsenals, I’m concerned that forage from deer and goats would motivate them (the plants) to throw out a lot of new growth.”

Conference participants were able to take one of four opportunities to see the area’s invasive species and the efforts to remove them. Trips included Natural Bridge State Park, where they saw the invasive nature of the hemlock woolly adelgid, an insect that attacks hemlock trees; UK’s Maine Chance Research Farm and Kentucky Horse Park, where they learned about invasive species’ effects on stream quality and saw restoration efforts along Cane Run Creek; UK’s main campus for an invasive removal planning workshop; or Raven Run in southern Fayette County.

At Raven Run, conference participants got an up-close look at honeysuckle’s invasive properties. Before it became a nature sanctuary, a portion of Raven Run was a farm. After the land was abandoned as farmland, invasive plants including bush and Japanese honeysuckle and garlic mustard, came into the area.

“One of the obvious things that we have seen on this trip is that honeysuckles are out-competing the native, beautiful wildflowers and preventing most of the native tree regenerations,” Fei said. “You can see a wall of honeysuckle, but you don’t have the native regeneration coming up. So in the long run, you will have a forest of honeysuckle without any diversity left.”

Removal and eradication efforts are underway throughout the area, including at Raven Run and Floracliff. At Raven Run, conference participants learned about the tools sanctuary employees use in honeysuckle removal and were able to try them out. But sustained eradication is very challenging.

“It’s very expensive to treat and also there’s the labor,” James said. “We only have three people on staff where I work. That’s one full-time and two part-time people. You can only cover about 10 acres a year. We’re dealing with about 300 acres, and most of it has exotic plants.”

Fei said it would take a community-wide effort to address the problem—homeowners, landowners, nursery owners, researchers and municipal and state governments.

“A collective effort and collective knowledge will make this happen,” he said.  

But it’s not simply a matter of convincing nursery owners and landscapers to stop offering the plants or convincing people to dig them up from their landscapes.

 “We as scientists and researchers need to step up,” Fei said. “If we tell them (something’s) not good, we need to provide a solution for the industry itself. For instance, bush honeysuckle is bad, but maybe you use alternate-leaf dogwood or spicebush to replace that species.”

It’s not just controlling the invasive species already in the state. Woodland owners, homeowners, landscape companies, nurseries and home and garden centers need to be aware of new invasive insects and plants entering Kentucky and control methods and treatment options. The hemlock woolly adelgid was first found in 2006 Harlan County and has since spread west to Natural Bridge State Park in Powell County and the Big South Fork in McCreary County.

At Raven Run, the staff, like the rest of Fayette County, may have to contend with the emerald ash borer soon, an invasive insect that attacks and eventually kills ash trees. The emerald ash borer has slowly migrated south from Michigan where it was first found in 2002. It appeared in Kentucky in 2009.

“Ten percent of the street trees in Fayette County are ash, so people are starting to expect a lot of mortality with that tree, and it will potentially cost the city a lot monetarily,” Fei said. “Prevention and treatment are really important if we want to keep this species. Remember moving firewood assists the spread of this insect.”