Rod Walker stretched his arm out toward the mountains north of his 1,500 acres abutting Shenandoah National Park in Albemarle County. The view was possible because of an opening where dead trees, strangled by oriental bittersweet and grapevine, had been removed.

Bittersweet, ailanthus, Japanese stilt grass, garlic mustard — these are some of the invasive species that Walker has targeted in a control plan he’s implementing a step at a time.

It’s no easy task, because invasive species — defined as a nonnative species that when introduced causes economic or environmental harm or harm to human health — often outcompete natives, thus interfering with ecological succession and, in turn, promoting other invasive plants and animals. Invasives significantly affect the food web; alter soil chemistry and nutrient cycling; change hydrology; and increase the severity of fires.

But Walker’s interests go much further than the boundaries of his land. A retired executive, Walker is the driving force behind the creation of the Blue Ridge Partnership for Regional Invasive Species Management, or Blue Ridge PRISM.

PRISMs are one of several types of cooperative weed management organizations. They are prevalent in Western states, and starting to gain a toehold in Eastern states.

Walker’s interest started with his desire to better manage his own land, but has grown into almost a full-time job as he helps launch an organization that is focused on the 10 counties that surround Shenandoah National Park: Nelson, Augusta, Rockingham, Albemarle, Greene, Madison, Rappahannock, Page, Warren and Clark.

Walker grew up on 18 acres in Pennsylvania where hunting, fishing and making the most of the outdoors was a way of life. As he moved into business after college, he continued to nurture his love of the outdoors — purchasing 180 acres in West Virginia so he’d have an outdoors weekend retreat. A subsequent purchase of acreage in Wisconsin led him to learn about timber and land management.

Walker retired and settled on Middle Mountain Farm in Albemarle County, land he bought 20 years prior with plans to actively manage the land for timber, trout and other native species. But he made a startling discovery.

There were sections on his property that were completely overgrown with oriental bittersweet — places where bittersweet and grapevines, each thick as fists, were intertwined, growing up and over the trees, effectively smothering them. Over 20 years, two small patches of bittersweet had become three 10– to 20-acre sections, with vines so thick that bulldozers were needed to get to the interior so workers could cut the vines and paint their stumps with herbicides.

Walker, whose land shares more than a mile of boundary with Shenandoah National Park’s eastern slopes, knew that controlling the bittersweet — which is spread by wildlife that eat the seeds, as well as sprouting from the roots — wouldn’t mean much if only he defended his borders.

In 2013, Walker met with Jake Hughes, Shenandoah National Park’s lead biological science technician, who agreed that the park’s efforts — and Walker’s — needed to be coordinated lest the plants ping-pong across their borders.

They also discussed the possibility of wider, regional efforts.

Hughes, who manages invasive species in the 200,000-acre park with a small staff and ever-shrinking budget, said, “I told him about these cooperative weed management areas that are a big thing out West — and he just took it and ran with it.”

In spring 2014, the Blue Ridge PRISM went from casual discussions to a serious meeting to determine if there was enough regional interest to create a multi-county collaborative partnership.

Representatives from state and federal agencies, local land preservation nongovernmental agencies, along with private landowners and service groups like Virginia Master Naturalists, answered with a resounding “yes.”

It has been a little more than a year since that first meeting, and Blue Ridge PRISM has developed a strategic plan as well as organized working groups and a steering committee of lead agencies and landowners who are poised to sign a memorandum of understanding to formalize the organization. The group has identified their top 11 “bad actors” (all herbaceous), and is plugging into state and national networks to assist in rapid response efforts when new species of concern are confirmed.

Ruth Douglas, longtime board member of the Virginia Native Plant Society and the Mid-Atlantic Invasive Species Council, said, “The task of creating a cooperative weed management area is so daunting, but, even though it is a lot of work, the regional approach is really the way to go.”

Susan Sherman, president of the Shenandoah National Park Trust, which serves as the new organization’s fiscal agent, said that Walker’s style — and his background in systems and business – has been an asset, adding, “I sit on a lot of volunteer committees, and this one has quickly established operating procedures and is getting to work helping local landowners and coordinating efforts at this regional level.”

Walker knows that his background has been helpful. “I am a problem solver by training, so this is another problem. It’s big, it’s complicated, it’s daunting and you may never win. That doesn’t mean you can’t have an impact. I believe we can have an impact.”

And Blue Ridge PRISM isn’t working in a vacuum. Walker credits a wealth of fact sheets and other information from Midwest cooperative weed management areas that the group has adopted so as not to reinvent the wheel.

Being a landowner, Walker has made sure to network with other landowners. “Some of these cooperative weed management areas do seem like they are arms of state or federal land management agencies. The Blue Ridge PRISM is really unusual in having such a strong landowner focus,” Hughes said.

“One of the programs we’re trying to start is specifically for landowners who want to understand — and maybe control — how invasives are affecting their properties,” Walker said. The group hopes that local master naturalists can be used to meet with landowners, walk the land and advise about invasive species controls .

“Sharing information is one of the most important things that these kinds of groups can do,” said Jil Swearingen, integrated pest management and invasives species coordinator for the National Park Service’s National Capitol Region.

Having informational tools — guides, fact sheets, online resources, digital apps — is essential for local groups to be able to figure out how to deal with specific local situations and coordinate with larger efforts, especially in developing rapid response teams, key to managing invasive species before they gain traction in a region.

Swearingen is also active with the Mid-Atlantic Invasive Species Council, which collaborates on issues in each Bay watershed state. The states all have some efforts to control invasive species. Maryland prohibits the sale of certain nonnative species. The District of Columbia has a cooperative weed management group that oversees rapid response and control as well as groups of trained Weed Warriors. Pennsylvania relies on a statewide coordinating council.

Though Virginia wrote an invasive species management plan and has employees dedicated to invasives control, Blue Ridge PRISM is Virginia’s only weed management partnership. The Potomac Highlands Cooperative Weed and Pest Management Area, which covers the headwaters of the Potomac River in both Virginia and West Virginia, operates out of West Virginia.

Most invasive species activities are strongly linked to efforts to maintain and restore native plants. This makes sense: Invasive species, by definition, crowd out native species — and native species are key to restoration work.

Not everyone agrees that invasive species should be controlled. Some believe that nature should be allowed to take its course, and that the methods, especially chemicals, used to control native species may create worse problems. Glyphosate, the active ingredient in Roundup – one of the most widely used chemicals by land managers, landscape maintenance companies and homeowners — has been linked to the decline of pollinators. The ultimate fate of — and effects from — most of the chemical compounds in use to control invasive plant species are unknown and still under study.

In the July issue of Harpers, David Theodoropoulos, author of “Invasion Biology: Critique of a Pseudoscience,” is quoted: “Thirty years ago, the greatest threats to nature were chainsaws, bulldozers and poisons. Now the greatest threats are wild plants and animals. And what do we use to fight them? Chain saws, bulldozers and poisons.”

But Walker said, “I don’t think any of us really want to use herbicides. And certainly no more than absolutely necessary.” But for large areas, removing invasive plants by hand or machine simply costs too much.

“Most of us look at the individual species and make judgments as to whether it is possible to suppress (but not eliminate) them, the seriousness of the damage they will cause if untreated, the costs of treatment, safety issues and any fallout or side effects,” Walker said. 

Empowering landowners to make individual choices is what Blue Ridge PRISM is about. For those who have no doubt that controlling the worst invasive species is the right way to go, this growing collaboration has brought hope in the face of what can seem like a Sisyphean task. Energetic conversations on the PRISM’s e-mail list, such as how to control Japanese stilt grass in different settings, bear witness to the eagerness for sharing techniques.

Douglas said, “There is now a much bigger community, and being part of Blue Ridge PRISM has brought me some hope.”


  • Plant Invaders of Mid-Atlantic Natural Areas, 2014 edition: To download information on invasive species, groups and resources in the Bay
  • Atlantic Early Detection Network: To report invasive species observations via computer or smartphone:
  • Mid-Atlantic Invasive Plant Council: Provides regional leadership to address the threat of invasive plants to the mid-Atlantic’s native flora, fauna and natural habitats:
  • Washington DC Cooperative Weed Management Area:
  • MapInvasives: This network of natural resources organizations, provides GIS-based data management system to assist citizen scientists and natural resource managers working to protect natural resources from the threat of invasive species. A digital app can be used to identify and map invasive species: