Invasive Plant Management
Photo: E. Wallace
Though it smells wonderful and brings back happy childhood memories of sipping honey from its tubular flowers, Japanese honeysuckle (Lonicera japonica) is no friend to the environment. Its story is similar to that of many invasive non-native plants. After being introduced around 1800 on Long Island, NY (NYIS info), as an ornamental that could control erosion and confer wildlife benefits, it spread like wildfire so that, today, it strangles native vegetation throughout North America and in many parts of the world. Invasive non-natives often outcompete native plants because in their new location they have escaped the regulating species such as insects and other animals that would normally eat them, or diseases that would check their growth. James River Master Naturalists are encouraged to learn to identify invasive non-native plant species and to partner with others to remove them from public grounds. While early detection and rapid response are the best approaches for managing these plants, we have unfortunately inherited many situations where they are out of control.
Photo: S. Shepherd
On a Continuing Education walk in Goochland County's Tucker Park, volunteers learn to identify some of the many invasive species there. Representatives from the James River Association and Goochland County Parks and Rec led the walk.
Blue Ridge PRISM [Partnership for Regional Invasive Species Management] is the closest Cooperative Weed Management Area (or Cooperative Invasive Species Management Area - CISMA) for our region. This organization offers invaluable education and support on how to approach invasive control effectively and safely.
A new and growing resource spearheaded by Blue Ridge PRISM is the Virginia Invasive Plant Coalition, which unites the efforts of over 75 private, public, and non-profit groups (including Virginia Master Naturalists) to reduce invasives and increase native plants in Virginia. See their ID & Control Tool with photos, links to Blue Ridge PRISM fact sheets, and to Penn State Extension ID videos.
Invasive Management Is a Long Game:
Examples of JRMN's on-going work
Tucker Park, Goochland
On a sunny day in January, volunteers tackle invasive vines at Tucker Park. Winter, when ticks, snakes, and the plants themselves are dormant, is often a great time to remove or kill plants that threaten the ecosystem. The Virginia Department of Forestry provides guidelines for the best times and techniques for tackling a particular species. Using the least harmful and most effective strategies for controlling invasive is known as Integrated Pest Management (IPM).
Photos: S. Shepherd
Hidden Rock Park, Goochland
Anyone who has been gardening or landscaping for a while will probably admit to having brought home an attractive plant from the local garden center without realizing its potential for taking over the landscape. Some garden centers are waking up to the damage done to the environment by these plants, but many nurseries continue to sell them. The leatherleaf mahonias (Mahonia bealei) framing the entrance to this trail in Hidden Rock Park were most likely purchased at a garden center where they were recommended as durable evergreen shrubs, but volunteer mahonias are now scattered throughout the park, planted by birds who eat the plant's blue berries. If birds and other wildlife eat the fruit, can the plants be bad? The answer is "yes" if those plants spread aggressively and outcompete natives. A better approach to feeding the birds is to encourage fruit-bearing native plants that feed not only birds, but also the caterpillars and bees that evolved alongside them in our region.
Photos: S. Shepherd
With permission from park officials, JRMN volunteers removed the entryway mahonias and will keep a watchful eye out for regrowth and new seedlings.
In the last days of winter, red maples are blooming, and spring ephemerals are peaking out here and there. Bluebirds are already staking out the bird boxes at the park. But non-native invasives are lurking amongst our native spring beauties, waiting to overtake them. At this time of year, JRMN volunteers target two time-sensitive invasive species at Powhatan State Park and Fighting Creek Park, pulling them before they go to seed in mid April: Garlic Mustard and Incised Fumewort.
Photo: D. Girgente
Photo: S. Shepherd
Garlic Mustard (Alliaria petiolata)
According to The Nature Conservancy, this herbaceous annual was introduced in the mid-1800s as an herbal medicinal good for erosion control. Now it is rampant in the East, Midwest, and Northwest US. Garlic mustard spreads by seeds that are viable in the soil for years, but it is easily pulled (and bagged) before its flowers set new ones. Like many non-native invasives, it has adaptations that increase its competitive edge, in this case, chemicals released by its roots that alter fungal networks in the soil many native plants need in order to thrive. Garlic mustard's allelopathic activity discourages other plants including native trees from sprouting nearby.
Incised Fumewort (Corydalis incisa)
This lovely annual/biennial from East Asia has recently emerged as a "high risk" invasive species, according to the National Park Service. First observed in 2005 in the NY Botanical Garden, it has since spread quickly in 4 eastern states (including Virginia) and is making appearances in others. Incised fumewort spreads by projectile seeds that can be moved by water, but because the flowers are attractive, it will no doubt be spread by well intentioned gardeners too. Once again, early detection and rapid response (EDRR) are critical to prevent this plant from becoming a serious problem in woodland settings throughout the East. A vigilant JRMN volunteer recently discovered a spreading patch of incised fumewort in Fighting Creek Park in Powhatan and, after enlisting the help of others, set to work pulling it before it could go to seed. After removing what they could, the volunteers put down cardboard and covered it with mulch to slow down reseeding.
Photo: D. Girgente
Photo: S. Shepherd
Photo: D. Girgente
The List Goes On . . .
A recent survey sent by Blue Ridge PRISM to determine the most problematic invasive plants in the region provided a list of over 100 species to choose from (not including invasive aquatics). JRMN volunteers have many of these plants on their radar and will continue to contribute to the state wide-effort to control them. Many hands and ongoing support from conservation organizations and concerned property owners will be required if we hope to check the spread of these pernicious threats to our environment.
(Microstegium vimineum)
According to the Blue Ridge PRISM fact sheet, this annual grass first appeared in 1919 in Tennessee, probably due to its use as a packing material in shipments of fragile items. It flourishes in deep shade and full sun, blanketing the ground and smothering native seedlings all over the eastern US as far as the Mississippi River. A single plant can spread 1000 seeds.
Photos: S. Shepherd
Chinese Bushclover (Sericea lespedeza)
Introduced in 1896 as a forage crop and for erosion control at strip mines, this perennial is a serious problem in the Eastern US and the Midwest. It's a good example of the many ways invasive species upset the balance of nature. 1) As a legume that fixes nitrogen, it increases soil fertility where it grows. Sounds good, but it isn't because additional enrichment discourages natives adapted to poor soil. 2) Chinese bushclover contains high levels of tannic acid with the result that wildlife avoid it. Instead of eating the invasive non-native, they more heavily browse native plants struggling to compete. 3) A single robust Sericea plant can produce 1,500 seeds, and they survive in the seed bank for years. 4) Its root system is deep and tenacious so that a colony of this plant makes the soil impenetrable to other plants. 5) As the photo below demonstrates, this invasive grows tall and then flops down on top of anything hardy enough to try to compete with it, blocking all access to the sun. [Blue Ridge PRISM factsheet]
Photo: S. Shepherd
Photo: S Oglesby
Wintercreeper (Euonymus fortunei)
Native to China, Korea, and Japan, wintercreeper was brought to the US in 1907 as an ornamental groundcover and is now naturalized throughout the eastern US. As a climbing vine, it can grow over the tops of trees and shrubs, blocking sunlight to lower plants with its evergreen, vigorous growth. It spreads by seeds eaten by wildlife or washed downstream as well as by suckers. Trailing vines along the ground take root at every node. Wintercreeper thrives in sun or shade, but is particularly a problem in forest habitat. The last photo shows how the vines were cut with a generous gap between to prevent reconnection. [USDA]
Photo: D. Girgente
Photo: E. Wallace
Photo: S. Shepherd
Tree-of-Heaven (Ailanthus altissima)
Native to China, tree-of-heaven was planted in a garden in Philadelphia in 1784 and is now widespread in 30 states--in fields, forest clearings, roadsides, vacant city lots, and even cracks in sidewalks. Its vigorous roots, like many other non-native invasives, produce toxins that prevent the growth of other plants. Tree-of-heaven is also the host of a seriously invasive insect, the spotted lanternfly, that destroys fruit crops and defoliates trees. [Blue Ridge PRISM factsheet]
Photos: S Oglesby
Introduced from China to the US in 1852 as an ornamental hedge, Chinese privet rapidly escaped into the wild due to its prolific seed dispersal by wildlife that eat its fruit and by root sprouts. Common throughout the southeastern US, it is capable of outcompeting and displacing native vegetation. [USDA/NRCS plantguide]
Photos: E. Wallace
Japanese Hops (Humulus japonicus)
Introduced to the US in the late 1800s as an ornamental and for herbal medicine, this annual vine spreads over trees, shrubs, and the ground, blanketing everything in its path. It is especially problematic in riparian zones. Seeds mature in September and sprout in spring. [Invasive.org]
![Jap Hops [Sandy]original-RR1000sm.jpg](https://static.wixstatic.com/media/b96594_3ea852f41cb84a98abbb7e7fbae6fcd5~mv2.jpg/v1/fill/w_278,h_371,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/Jap%20Hops%20%5BSandy%5Doriginal-RR1000sm.jpg)
Photos: S Oglesby
Photo: E. Wallace
Unfortunately, there are many more.
To print a free PDF of Invasive Plants of the Mid-Atlantic published by the National Park Service, click here. Learn to identify invasive species on your property and then consult Blue Ridge Prism for the appropriate steps to take to control their spread.