Unwanted Guests: Invasive Species Infiltrate the Garden State

A plague of invasive plants, animals and creepy-crawly things is crowding out Jersey's natural species. The state spends millions to stop the destruction, but the exotic invaders keep coming.

The Great Swamp in Morris County has its own strike team to battle invasives.
On a recent mission, Dorothy Fecske, wildlife biologist for the Great Swamp National Wildlife Refuge, left, and volunteer John Berry came armed against the rapidly spreading Callery pear trees.
Photo by Fred Conrad

Laurel Gould knows her plants. After a lifetime of digging, seeding and weeding, she needs no guidebook to identify what’s growing in the woods near her Tewksbury home.
But one day in early spring two years ago, something stumped her. Hiking on a hillside with Rocky and Casey, her Lab-mix companions, she glimpsed a plant about a foot tall, with broad, oval, green leaves and clear veins. She kept an eye on it over the following weeks. As it grew, it acted more like a vine than a flower. When it blossomed in June, she gave in and checked her Peterson Field Guide to Wildflowers, which identified the mystery plant as black swallow-wort, a member of the milkweed family.

Delighted to know the plant’s name, Gould, a retired librarian, decided to find out more. She checked several sources and then, on a hunch, called up the website of the New Jersey Invasive Species Strike Team, a nonprofit comprising private individuals and representatives of various community-based organizations and government entities. Their mission: to hunt down harmful emerging species and prevent their spread.

What she read terrified her. Black swallow-wort is a fast-growing, invasive vine that strangles other plants. Worse, while other members of the milkweed family provide important habitat for monarch butterflies, eggs left on swallow-wort are doomed to die.

“It’s a very bad plant,” says Gould. Soon after discovering its sinister nature, she grabbed a bottle of Roundup and stormed back up the hill to attack the dozens of specimens she had spotted. The following spring, when they sprouted again, she used a smartphone app that the strike team had just launched to report the number of plants she had poisoned.

This spring, the swallow-wort was back for yet another faceoff with Gould. It is a small battle in a wider war being waged all over New Jersey. Unwanted, uninvited and unloved plants—as well as animals, insects, fish and microscopic pathogens—have muscled into every corner of the state, crowding out native species and altering the forests, rivers, meadows and marshes integral to New Jersey.

Illustration by Golden Cosmos

Illustration by Golden Cosmos

The scale of destruction in the state is enormous, costing more than $290 million a year, according to one estimate. New Jersey spends more than $100,000 a year to combat the spread of just one plant—purple loosestrife—even as the showy but highly destructive species remains legal to sell and plant around the state.

“There is little doubt that we have already lost much to invasive species,” concludes the 2007 New Jersey Strategic Management Plan for Invasive Species.

The battle is not abating. Fifty new plant species have turned up in the state over the last 25 years, with two or three new exotics continuing to establish themselves on New Jersey soil every year.

Scarred battlefields testify to the intensity of this war. In Union and Middlesex counties alone, some 21,000 mature trees were lost to the Asian longhorned beetle before it was declared eradicated in 2013. At the Shore, MSX disease has reduced the state’s oyster harvest to less than 15 percent of its 1950s peak. Feral hogs roam parts of Gloucester County. The woolly adelgid, an insect, has wiped out entire stands of hemlock trees in Northern New Jersey. And since the first emerald ash borer was found last summer in Somerset County, the tiny insect has also been trapped in Mercer and Burlington counties and is expected to move on to other locales. Nearly every ash tree it infests dies.

Popular state landmarks like Jockey Hollow and parts of Allamuchy State Park are overrun with spiny Japanese barberry. Heavy blankets of mile-a-minute vine smother parts of the Watchung Reservation. Japanese knotweed assault the banks of the Delaware River. In the Great Swamp National Wildlife Refuge, where Gould volunteers, knotweed, chocolate vine and Callery pear trees are rampant. The knotweed, in particular, threatens the habitat of the bog turtle, an endangered species.

Many of these pests, which some refer to as biological pollutants, hitched rides on cargo unloaded at commercial ports. Others were introduced into the state as ornamental plants. Landscapers, property owners, even municipal governments then planted the newcomers or allowed them to flourish until they threatened entire landscapes.

“For me, the overriding concept is—and I won’t use any French—but we’ve really messed things up,” says Michael Van Clef, science director for the statewide strike team and principal author of the state’s 2007 strategic plan.

While neighboring states like New York and Connecticut have outlawed the sale or planting of many invasive species, the New Jersey Legislature has yet to pass any such law. That puts the burden on the strike team. What they lack in resources, they make up with passion and a tech-driven strategy that uses data to stay a step ahead of the invaders.

“We are smarter than the plants, but we don’t always act it,” says Van Clef, a wry, 45-year-old ecologist with a PhD. from Rutgers and his own conservation consulting company. “You’ve got to pick your battles.”

The strike team focuses on early detection and rapid response to search for and destroy invasives before they get a foothold. The new smartphone app is one of their tactical weapons. It has recruited a statewide network of observers who, like Gould, can identify invaders and report sightings to a central data bank.

Gould’s report was entered into the data bank, adding to the strike team’s information about black swallow-wort; it was already on the organization’s lengthy Do Not Plant list. Now the team knew the invader had a foothold in another location.

“That’s the whole point,” says Van Clef. Without a central repository of information about invasives, the swallow-wort “would have continued happily spreading all over.”

About 1,000 individuals downloaded the app in its first full year (it’s available free for Android and iPhone). They’ve used it to call in more than 530 reports.

The strike team’s executive director, Susan Brookman, says the app builds on what volunteers like Gould, who happens to be her neighbor, have been doing for years on their own. “Lots of people have been tracking the spread on their own properties, but now they will be reporting to a central location,” says Brookman. “That’s going to revolutionize the way we collect data.”

And with that data comes hope that the tide of this war can be turned in favor of the natural environment.

Illustration by Golden Cosmos

Illustration by Golden Cosmos

“What we do is not very complicated,” says Van Clef, talking strategy about invasives at his rural Warren County home, which doubles as his office. “We find them before they spread, and we kill them.”

The first non-native plants probably came with settlers who crossed the ocean with the seeds of useful plants in their baggage. The state’s diverse topography is one of the factors that make it a compliant host. It has been estimated that as many plant species grow here as in New York and Pennsylvania, states that are three to four times larger.

Not all introduced plants are invasive, but all the trouble makers share some nasty traits. They can survive in the wild, they produce mountains of seeds and their offspring take root easily. Most critically, they can crowd out natural species and reduce biodiversity.

While non-natives have been here for a long time, suburbanization and the proliferation of garden nurseries and big-box stores have drastically accelerated the spread of new species.

“In the 1950s, you could have gone anywhere and barely seen any invasive species outside of some honeysuckle or multiflora rose,” says Van Clef. Then came the building boom of the 1970s and “the rate of change of new species adding to the mix is like a rapid-fire Gatling gun. It’s stressing the ecosystem.”

In 2004, Governor Jim McGreevey recognized the threat and established the New Jersey Invasive Species Council. Van Clef drew up a strategic action plan for the council in 2007.

The plan, which was adopted in the waning days of the Corzine administration, recommended creation of a strike team to collect data from across the state and implement strategies to limit the spread of invasives, primarily by early detection.

In 2010, Governor Chris Christie swept away some 60 councils, commissions and task forces that he said were unnecessary. Among those to disappear were little-known groups like the Billboard Policy Procedure and Review Task Force and the Governor’s Study Group on the Bicentennial of the Polish Constitution.

The Invasive Species Council also got the axe.

But Van Clef’s work did not go to waste. With the Friends of Hopewell Valley Open Space, where he is stewardship director, as a base, and with help from other local organizations—most notably the Raritan Headwaters Association—he already had created the strike team. That effort brings together volunteers to collect data, monitor hot spots and provide arms and legs for eradication efforts.

In 2008, the strike team helped the New Jersey Conservation Foundation clean up a 50-acre parcel of land in Hunterdon County that contained about 10 ponds on a former commercial fish hatchery.

Great Swamp Invasives Strike Team volunteer Linda Jerdach goes after a young Callery pear tree with a large lopping tool.

Great Swamp Invasives Strike Team volunteer Linda Jerdach goes after a young Callery pear tree with a large lopping tool. Photo by Fred Conrad


Tim Morris, the foundation’s director of stewardship, recalls that about a year after the foundation purchased the hatchery land, a fisherman caught a bighead carp in one of the ponds whose waters empty into the Delaware River. That was bad news. The bighead—which in rare instances can grow to 100 pounds—is known to outcompete native species.

Morris asked Van Clef to help get rid of the carp. As they killed off the fish with rotenone, a natural poison made from the roots of tropical plants, they noticed clam-like mollusks neither had ever seen. Van Clef reached out to his network, and eventually the shell was identified as the Chinese pond mussel, an invasive species that had spread over Europe, but had not been documented in North America.

The state strike team now has a grant to eradicate the mussels and monitor the ponds to ensure that none escape.

“This very much echoes the whole philosophy of the strike team,” says Morris. “You quickly identify species that are invasive and going to cause problems, and you deal with them before they spread. Right now, it would be impossible to go to the Mississippi River and get rid of bighead carp. But by doing it back then, we don’t have a problem in the Delaware.”

The strike team’s phone app is based on a design developed at the University of Georgia, a leader in the field. Users can bring up the long list of invasives by name, accompanied by identifying photographs. Then, with a touch, they can send the strike team a report of what they found and where.

The team collects data from all over the state and, using a kind of biological triage, determines where best to deploy volunteers. Invasives are listed in four categories, from 0, which means fewer than 10 of a given species have been reported, to 3, when up to 999 have been identified. When a plant is all but uncontrollable, it is considered “widespread.”

“That’s when I say ‘uncle,’” Van Clef told more than 100 volunteers who gathered at Duke Farms in Hillsborough in early April for an annual conference on invasives.

Van Clef later made clear to the volunteers that the most important weapon in this war is information. The worst enemies may be people who don’t know the harm in what they are planting. That’s why, besides the smartphone app, the team’s website contains an exhaustive Do Not Plant list, and lists native alternatives. It warns that an excess of deer can wipe out native plants, leaving the door wide open for harmful non-natives.

Illustration by Golden Cosmos

Illustration by Golden Cosmos

Until the state adopts a more aggressive stance, such efforts are about all that blocks the way of the invaders. But in the last year, the New Jersey Legislature has finally gotten involved, though its primary target is running bamboo, which, while not a threat to forests and natural areas, Van Clef says can be “an outright aggravation” between neighbors.

Still, it is running bamboo that has caught the Legislature’s attention, mostly in response to a complaint from an Atlantic County nurse who bought a home last year without realizing that her neighbor’s bamboo grove was migrating into her yard.

Desperate for help, the homeowner reached out to her local assemblyman, Vincent Mazzeo (D-Northfield).

“This running bamboo, once it goes, it goes,” says Mazzeo. “You can’t do anything about it.”

Mazzeo introduced a bill (A-3452) that would impose fines on real estate agents who do not disclose the presence of bamboo to potential home buyers. The final version of the bill passed by the Assembly last December dropped that clause, but added a requirement that sellers disclose the presence of bamboo on their property. The bill also kept a controversial $100 fine for anyone who plants bamboo within 100 feet of a property line.

Seventeen assemblymen voted against the bill. One of them, Michael Patrick Carroll (R-Morris Plains), says he opposed the bill not because he thought it was a bad idea, but because it “effectively criminalizes unknowing behavior.”

“If you just happen to own a plant, suddenly you’re a criminal?” Carroll asks. He acknowledges that there’s room for a law controlling invasive species, but not this law.

As the bamboo bills awaits action in the state Senate, a more aggressive invasive species bill (A-3125) is stalled in the Assembly. It would prohibit the sale or planting of nine invasive species, including purple loosestrife and Japanese stiltgrass. However, the bill excludes Japanese barberry and many other invasive species that are being grown and sold in the state.

Despite those limitations, environmentalists are optimistic that Trenton is finally moving in the right direction.

“We look at it as a first step,” says Megan Tinsley, conservation advocate for the New Jersey Audubon Society. Tinsley says one reason New Jersey has fallen behind other states is because the landscape nursery industry has resisted attempts to control which plants can be sold.

Dominick Mondi, executive director of the New Jersey Nursery and Landscape Association, says growers are concerned about invasives, but cautions that if too many plants are categorized as invasives, it could hurt the industry and deprive property owners of varieties of popular plants.

“There’s a difference of opinion,” says Mondi. “On the big picture of invasives, we agree that it’s a huge problem. But when it comes down to plants, there does get to be some disagreement with how some certain species are treated and classified.” He says some varieties of barberry, for example, are not harmful, although that is open to debate.

Illustration by Golden Cosmos

Illustration by Golden Cosmos

While the Legislature has been reluctant to take on invasive plants, other parts of state government are deeply engaged in the battle against insect pests, which are a much bigger and potentially costlier problem. Paul J. Kurtz, an entomologist with the New Jersey Department of Agriculture, says the greatest threat right now is the emerald ash borer, a tiny jewel beetle that has wiped out 50 million ash trees around the country since it was discovered in Michigan in 2002.

Despite being smaller than a penny, the ash borer has managed to travel hundreds of miles into 25 states and two Canadian provinces since 2002, in large measure because of help from unwitting humans who transport firewood from infested areas.

“They can go as far as you’re going,” Kurtz says. “That’s why we always caution people about the movement of firewood, especially during the summer.”

Kurtz says campsites don’t have profits in mind when they forbid campers from bringing their own firewood. “They want to protect the forest,” he explains.

To eradicate the invaders, the strike team cuts dwn what it can and sprays the remnants with an herbicide that blocks future growth.

The Great Swamp’s Callery pear trees were left behind by a commercial nursery that had closed. To eradicate the invaders, the strike team cuts down what it can and sprays the remnants with an herbicide. Photo by Fred Conrad

The four confirmed detections of the ash borer in New Jersey have triggered a massive effort to track the bug’s movement. Kurtz says the state is deploying special traps in more than 100 municipalities this summer and monitoring them to see where the ash borer is heading next.

A number of emerging species are on the state’s watch list. Kurtz is concerned about the spotted lantern fly that has been attacking a broad range of trees, especially fruit trees, in Pennsylvania, and a walnut twig beetle, also seen in Pennsylvania, that can kill black walnut trees. He’s also monitoring a number of snails that have slipped into the state from other countries and now threaten Jersey crops. Exotic snails have been found attached to imported granite slabs used for kitchen countertops. The cernuella virgata, a small, inedible snail from Asia, was discovered just outside Port Salem several years ago. About the size of a pea, the snail moves slowly but reproduces quickly, and in a short time, it can completely infest grain fields, contaminating the crops with its feces and clogging the tines of mechanical harvesters.

Kurtz has worked with the strike team on a limited basis; he even has their app on his smartphone. “Some of the things on their list are on our lists as well, especially forest pests,” he says. But he says there’s a difference in approach. While the volunteers operate on a “see something, say something,” basis, the state uses scientific data, official programs and field scientists with lures and traps—as well as reports from the public—to determine the presence of invaders.

In the end, he says, “we all work in concert with each other to minimize and eliminate threats.”

In the uncommon chill of a late April morning, Laurel Gould and a half dozen other volunteers pull on work gloves and boots and march into an overgrown patch of woods at the edge of the Great Swamp National Wildlife Refuge in Morris County.

They head toward a huge grove of Callery pear trees blooming with telltale white flowers. The area was once a commercial nursery, and Callery—or Bradford—pear once was a darling of landscapers throughout the state because of those spring blossoms. Tens of thousands of the trees still flourish on suburban streets, in shopping malls and on university campuses across New Jersey.

But the trees fell out of favor when their weak limbs snapped in the state’s storms. When the nursery went out of business, the Great Swamp acquired the land, along with the remaining Callery pears and all their seedlings, plentiful enough now to crowd out native species that provide habitat for the bog turtle.

The volunteers, who form the Great Swamp’s own strike team, quickly spread through the undergrowth. The old nursery is a hotbed of invasive species, and from it have sprouted not just the Callery pear trees, but a towering grove of bamboo, a mess of chocolate vine, and even some trifoliate orange, a pesky deciduous shrub.

“This is really depressing,” says John Berry, a freelance editor who volunteers twice a month to clear out unwanted plants. “It’s a Callery forest.”

Berry’s job this day is to coat the base of Callery pear trees with a powerful herbicide. When he’s done, they look like they are slathered with strawberry jam. The poison gets drawn into growing tissue and kills the tree. The application takes just a minute, but the task is enormous because of the sheer number of trees.

Left to proliferate, the Callery pears will crowd out native species.

Left to proliferate, the Callery trees will crowd out native species. Photo by Fred Conrad

Ordinarily, such an infestation would be considered too far gone, hopelessly widespread in the state strike team’s categorization terms. But, as Berry explains, the trees pose a threat to the rest of the refuge. “Unless we get them now, it will only become much worse,” he says.

And so, despite the enormous odds, the volunteers engage Callery pear at every turn. Stephen Gruber, a retired chemist, sprays herbicide on those too big to cut, while Linda Jerdach uses a pair of loppers to take down spindly young ones.

“Oh, we’ve got a lot over here,” says Jerdach, a retired nutritionist, lunging at a clump of trees, each about the thickness of a broom handle. She grunts as she shuts the loppers. Some take more effort than others, but Jerdach is not deterred.

“For every one we don’t get,” she says, gasping for breath, “next year there’ll be 10 or 20 more.”

They work all morning, struggling through the saplings and thorny vines of multiflora rose. At noon, they head back to their cars, tired and bloodied, their hands pricked by the barberry bristles, their pants ripped by rose thorns.

Making her way through the underbrush, Gould takes note of a spiral of green gently poking through last season’s brown grass. “Sensitive fern,” she exclaims, excitedly pointing to the New Jersey native that is reaching for the sun of another season, defiantly staking out its space against the uninvited species all around it.

For Gould, the appearance of the fern is a sign that the fight to restore a natural balance is worth waging, despite the overwhelming odds. “There’s hope,” she says, gazing into the woods beyond the doomed Callery pears.

Anthony DePalma is the writer in residence at Seton Hall University and author, most recently of Here: A Biography of the New American Continent (Kindle e-book, 2014).

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