An Asian invasive, more bitter than sweet

Today’s blog post comes from Jordon Tourville, an intern with USFWS at the Rhode Island National Wildlife Refuge Complex. He is interested in invasive plant management and policy as well as hiking around New England.

As you drive along the highway this summer you’re probably thinking about a few different things, none of which are probably concerned with invasive plants. While your eyes are focused on the road (hopefully), you may not ever notice the jungle of vegetation growing like a wall on either side of you. Here in southern New England, there is a pretty good chance that a large portion of that sea of green around you is composed of a lovely invasive vine known as oriental bittersweet. Given that this plant is so common throughout the region these days, it might surprise you to learn that it was essentially unknown in the area 100 years ago. Where did it come from? Why is it here? The answers to these questions can be unearthed (no pun intended) with a little historical and ecological digging.

The fruit of Oriental Bittersweet (Celastrus orbiculatus) turns bright red in September when it ripens. Each fruit contains 3-6 seeds. Seeds are spread by wildlife that eat the fruit as well as by people who use the vines with colorful berries in decorative wreaths. (David Smith, Delaware Wildflowers) 

Oriental Bittersweet is native to eastern Asia, specifically northern China, Korea, and Japan. According to Peter Del Tredici of the Arnold Arboretum, the first recorded shipment of seeds and subsequent cultivation of the vine in the US was in 1879, when a certain Samuel Parsons sent them to the Arnold Arboretum outside Boston. Parsons procured these seeds from a man named Thomas Hogg Jr., an industrious person also responsible for the introduction of kudzu and other well-known invasive plants from Japan. These plants were so successful in the Arboretum, that after 10 years of cultivation they were up for sale at Kissena Nurseries in Flushing, New York.

Horticulturists were amazed by how many fruit the vine produced and how gorgeous the plant appeared in the fall. Due to its growing popularity as an ornamental, the next 30 years were characterized by rapid expansion of the plant into new markets. It was grown in the New York Botanical Garden, sold in nurseries in New England and as far south as Ashville, North Carolina, and planted as an ornamental and a hedge plant in countless gardens. In later years, several states (including Rhode Island) suggested that oriental bittersweet be used as a highway bank planting.

The most reliable way to identify Oriental bittersweet from the much rarer American bittersweet is by their fruit. The Oriental bittersweet has clusters of 1-3 fruits attached at leaf axils along the stems. The fruit of American bittersweet is found only at the tip of the stem. (Monika Chandler, Minnesota Department of Agriculture)

While several individuals and papers urged caution in promoting this vine, it wasn’t until 1973, when an article entitled “Distribution of Oriental Bittersweet in the United States” by David Patterson, did the threats posed by Oriental Bittersweet really become acknowledged. Unfortunately, bittersweet had already long since escaped cultivation and today grows at thousands of sites in 25 states.

The next time you drive down the highway and you happen to glance at the side of the road, you might be shocked by the amount of oriental bittersweet you see that you never noticed before. You will see the bright green leaves all stemming from twisted green stalks. The US Fish and Wildlife service is making an effort to stem the tide and minimize the impact of this particular invasive, but any help is appreciated. If you find this vine growing around your house you can always cut or mow it at its base to help slow its growth and reproduction. It is very tenacious so multiple treatments will be necessary, but be persistent. With enough effort, maybe we can one day stop worrying about these invasive vines and go back to thinking about a nice drive to the beach.

Oriental Bittersweet will climb over most other vegetation, and will appear as a tangled mass of vines and leaves when passing it on the road in the summer. (Jordon Tourville/USFWS)

 

 

A black swallowwort by any other name is still just as toxic

Today’s blog post comes from Jordon Tourville, an intern with USFWS at the Rhode Island National Wildlife Refuge Complex. He is interested in invasive plant management and policy as well as hiking around New England.

As an Invasives Intern with USFWS in Rhode Island, I have the unfortunate privilege to find some of the worst invasive plants in the country. I’ve engaged in hand to hand combat with oriental bittersweet vines 50 feet tall and sailed through seas of Japanese knotweed. Given all of this, I believe that one of the most dastardly invasives out there is black swallowwort (Vincetoxicum nigrum).

Black swallowwort vines will completely cover any ground structure Photo credit: Jordan Tourville/USFWS

Known also by its street name, the dog strangling vine, this plant has the potential to harm a multitude of different species from all walks of life. Introduced to the United States as an ornamental from Eastern Europe around 1854, black swallowwort can now be found throughout the northeast. Its large shiny dark-green leaves and its sinister looking dark purple to black flowers make it very easy to spot. It’s true that at first glance this vine might not seem too bad, but just beneath its beautiful exterior lays a deadly siren call to all of our beloved monarch butterflies.

While the roots of black swallowwort are toxic to mammals, the leaves are equally unpalatable for some insects, which include the monarch butterfly. Given the physical similarities and habitat overlap between black swallowwort and the common native monarch host plant, milkweed, adult monarchs will occasionally lay their eggs on the invasive vine. The result is mass mortality of monarch larvae, and yet another blow to our efforts in restoring their population numbers.

Adult monarch butterfly
Photo credit: Anne-Marie Conard/USDA Forest Service

Instead of throwing in the towel and continuing to allow black swallowwort to plague our lands, livestock and butterflies, an enterprising team out of the University of Rhode Island is experimenting with different insects and other biocontrol agents. Their goal is to find the right candidate that will stem the tide of the swallowwort invasion. Given more time and the right resources, we may soon have a new weapon with which to strike back against this reckless invader.

USFWS staff and volunteers manually pulling black swallowwort regrowth. Biocontrol aganets are also needed for effective control of this plant. Hypena opulenta is one moth which shows great promise as a biocontrol agent.

Black swallowwort, the dog strangling vine, my worst nightmare; any one of these names could be applied to this robust invasive plant species, but regardless of its label, black swallowwort continues to be a toxic plant that causes untold harm to us and to threatened species that we are trying to protect.

Chesapeake Bay almost rid of invasive nutria

When they feed, nutria damage or destroy the root mat that binds the marsh together. When this fibrous root network is lost, marshlands are quickly reduced to unconsolidated mudflats. These areas, in turn, are highly susceptible to erosion and are eventually converted to open water. This downward spiraling not only harms the marsh but the wildlife that depend on them. In a 2004 economic study commissioned by the Maryland DNR, Southwick Associates reported that, without decisive action, more than 35,000 acres of Chesapeake Bay marshes could be destroyed by nutria in 50 years. Credit: USFWS

Today you’re hearing from Dan Murphy (top), chief of habitat conservation in our Chesapeake Bay Field Office, and Suzanne Baird, manager of the
Chesapeake Marshlands National Wildlife Refuge Complex. Photos courtesy of Dan and Suzanne.

Down in the Chesapeake Bay, we’ve made great progress to get rid of the exotic, invasive nutria rodent. So well that we invited our regional agency leadership from Massachusetts down for a  tour of Chesapeake Bay marshes and a demonstration of nutria eradication methods.

Scott Kahan and Paul Phifer, the heads of two of our Northeast Region programs, visited us for two days to get a firsthand look at this highly successful project that has eradicated the exotic invasive nutria from 216,000 acres of wetlands on the Delmarva Peninsula. Nutria are aquatic rodents that degrade wetlands through their destructive feeding habits.

In fact, Blackwater National Wildlife Refuge has lost almost half of its wetlands since the introduction of nutria, which accelerate and exacerbate the effects of other forces, such as sea-level rise.

The project is the first attempt of its kind to eradicate an aquatic mammal from a non-island locale. While similar projects attempt to control nutria, our Chesapeake Bay Nutria Eradication Project endeavors to remove the species permanently, restoring and protecting the Chesapeake Bay marshes that provide valuable wetland habitat for birds and fish and serve as a nursery ground for commercially important aquatic species, such as the blue crab. Also known as the kidneys of the Bay, Chesapeake wetlands filter harmful runoff that reduces water quality.

A USDA wildlife specialist setting a nutria trap. Credit: Steve Kendrot, USDA-APHIS Wildlife Services

The project is funded by two of our agency’s programs, the National Wildlife  Refuge System and Partners for Fish and Wildlife Program, and supported by 27 partner organizations. The Service’s Chesapeake Bay Field Office and Chesapeake Bay Marshlands National Wildlife Refuge Complex administer the project, implemented by a crew of 17 federal wildlife specialists from the Department of Agriculture’s APHIS Wildlife Services.

We’re excited to be moving operations into the final remaining Chesapeake Bay river valley that is known to be infested by nutria. It was great to have Scott and Paul there to help us celebrate this hard-won occasion. For many years, the wildlife specialists have exhaustively searched for and captured nutria year-round in extremely harsh conditions.

Paul Phifer and Scott Kahan, the heads of two of our Northeast Region programs, discuss nutria eradication techniques with Dan Dawson of USDA-APHIS Wildlife Services. Credit: Steve Kendrot, USDA-APHIS Wildlife Services

Having our leadership take time out of their busy schedules to look in-depth at a project and show interest and appreciation meant a lot to the hard-working and dedicated crew. We feel confident that the goal of a nutria-free Chesapeake Bay is possible as long as we maintain the current level of effort and see the project through to completion.  Having a vote of confidence from the top gives us some tailwind.

See more photos from the day on Scott’s Facebook.