Invasive plant species anywhere on the homestead are a problem for the way they displace native species, disrupt ecosystem function, and generally make a nuisance of themselves, but they can be a serious problem in the woodlot, where the growth of healthy trees is an economic necessity.
We call these non-native plants invasive because they invade and out-compete native plants for water, soil, sunlight, nutrients, and space. Over time, invaders like kudzu and garlic mustard can completely take over, creating generally poor habitat for wildlife and reducing the forest’s ability to regenerate itself. That’s not news to most woodlot owners; however, as anyone that has tried to kill invasive plants can tell you, getting rid of them is a tedious and frustrating task.
Exasperated landowners have struggled with controlling invasive plants in recent years with varying results, mostly due to a lack of information on how to deal with the problem. While entire books have been written about combating invasive plants, there are three basic steps involved in getting rid of these scourges: identification, assessment, and eradication. A word of advice: do your due diligence and fully research all your options to avoid setting yourself up for failure. If you decide to hire a contractor to do the work, your local USDA office should be able to put you in touch with a specialist in your area.
Identify the Offending Invasive Species
The first and most important step is to identify invasives on your property so that you can control them before they become a problem. While this might sound easy enough, the list of potential invaders in our yards and woodlots is long enough that identifying them can be a daunting task. Fortunately, there are several online sources you can use to find out which invasives you’re most likely to see in your area. A good place to start is www.invasive.org, published by the University of Georgia’s Center for Invasive Species and Ecosystem Health. Aside from offering a wealth of general information on invasives, you can browse by state to bring up a list that includes a lengthy description of each species along with photographs to help with identification.
Another source for identifying invasives is the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). Each state has an NRCS office that publishes a brochure identifying the most prevalent non-native, invasive plant species in the state including plant descriptions, history, habitat, the ecological threat they pose, and possible controls and preventative measures that could reduce their impact on the forest.
If you’re still unable to identify an offending species, you can contact your county’s Cooperative Extension Service (CES) to obtain assistance from a state specialist or area agent (see Land Grant University Website Directory – Extension). CES is operated through the nation’s Land-Grant University System in partnership with state and local governments. Scroll down and click on the map to bring up your state. Be aware that the COVID-19 pandemic has impacted the ability and timeliness of personnel to provide assistance.
Assess the Problem
Once you know what you’re dealing with, you can come up with a plan for removal. If you have a few plants, and they are small, you might be able to get away with pulling out these invaders by hand. If they cover a bigger area and are more established, the job might require more “muscle” in the form of power tools. Your plan for how to deal with them should take into consideration the size and scope of the job, the amount of time you have to put into the project, and your overall goals. You need to be realistic. If the plants are too big or too plentiful, or you don’t have time to spend removing them, you’ll never get satisfactory control, and you’ll end up frustrated, having made no difference in the population of these species on your property.
Bear in mind that some plants are toxic and just touching them can cause skin irritation and respiratory problems. It’s a good idea to research the toxicity of the plants you want to remove so you know what to expect and wear gloves to avoid contact with any part of the plant that may cause a reaction.
Plan of Attack for Managing Invasive Plant Species
If pulling, make sure that you pull out the entire root system and hang them in a nearby tree to dry out (all of these plants can sprout from even a small fragment of root). Pulling can be effective when the plants are young, the infestation has just started, and the plants haven’t yet flowered or produced seeds. Older infestations where the plants have matured and dropped their seeds for several years can be tackled with pulling, but you can wind up creating ideal conditions for seed germination of the plants you are trying to get rid of. Pulling plants loosens the soil in a way that makes seed germination more successful. The use of a digging fork is preferential to a shovel, as shovels can shear off portions of the root system, allowing for regrowth.
To remove larger woody stems (up to about three inches in diameter), the experts recommend using a Weed Wrench™, Root Jack, Root Talon, or similar tool. These tools are available from several manufacturers and are designed to remove the aboveground portion of the plant as well as the entire root system. You can try cutting them with a hand saw, brush saw, or chainsaw, but be warned that all exotic invasive species sprout prolifically after cutting and will require follow-up treatment (translation: they will be around forever).
Big Jobs Require Big Solutions: Herbicides
Most advanced infestations, from forest understories to hedgerows and old farm fields, will require chemical removal—the application of herbicide—to get any measure of control. While some landowners adamantly oppose using chemicals on their property, herbicides are an important tool in rehabbing an unhealthy forest and keeping it healthy into the future. Herbicide can be applied conscientiously and thoughtfully, either to the cut surface of stumps or as a low-intensity foliar spray, applied to the leaves of the target plants. Either treatment method can be executed with very little to no mortality of native plants in the immediate area. If unsure of the “reach” of an herbicide through runoff, test it first on a small area before applying it to the target area.
Most of the commonly known invasive plants can be treated using only two herbicides: glyphosate (the active ingredient in Roundup™ and Rodeo™) and triclopyr (the active ingredient in Brush-BGon™ and Garlon™). Glyphosate is non-selective, meaning it kills everything it contacts. Triclopyr is selective and does not injure monocots such as grasses, orchids, lilies, etc. Read the manufacturer labels and follow directions carefully for both environmental and personal safety, and do some research on what equipment to use and when to apply to your target species. Further information on herbicide use and application for invasive species can be found on the University of Florida’s Institute of Food and Agricultural Sciences website.
These are relatively benign herbicides, but when improperly used they can cause both short- and long-term health and environmental problems. Keep livestock and pets out of the treated area until it is fully air-dried. Herbicide application can be expensive, but if you have a forest management plan, you can apply to the NRCS’s Environmental Quality Incentives Program (EQIP), for help with funding and carrying out your invasive species treatment project.
Important Note: All projects in wetlands or aquatic systems fall under the jurisdiction of the Wetlands Protection Act, and therefore require a permit. Yes, even hand-pulling that colony of glossy buckthorn plants from your own swampland requires a permit. The entity charged with enforcement of the Wetlands Protection Act varies from state to state, so you might have to make a couple of calls to find the office that handles environmental or water quality issues in your area.
Regardless of the method chosen to control invasives, it’s important to recognize that even if we get out there and pull, cut, or treat all the invasive exotic plants on our land, it’s almost impossible to completely eliminate them. Birds drop seeds as they fly from place to place, or they will be spread by some other means.
The steps of identification, assessment, and treatment covered here are not a path with an endpoint, but rather a cycle that must occur continuously into the indefinite future. Since nature is dynamic, complete eradication of invasive plants is a moving target.
Our problem is Johnson grass – – – we are trying anything at this point – it is taking over every part of our tiny farm – the garden I pull buckets of roots each year – – – we put down weed barrier and build beds above and soon it is in the bed – if you have ideas, please let us know.
A couple things that this article does not mention, which may or may not be useful to many–especially given widespread invasion–are the ideas of harvesting and using or selling the products they produce; fighting the invasive by out-competing them; blocking all light until they die; using other natural means for controlling them.
Kudzu is extremely useful and marketable. From rxlist.com: “Kudzu’s root, flower, and leaf are used to make medicine. It has been used in Chinese medicine since at least 200 BC. As early as 600 AD, it was used to treat alcoholism. Today, kudzu is used to treat alcoholism and to reduce symptoms of alcohol hangover, including headache, upset stomach, dizziness, and vomiting. It also treats angina, menopause symptoms, muscle pain, measles, dysentery, stomach pain (gastritis), fever, diarrhea, thirst, neck stiffness, and to promote sweating. Other oral uses include treatment of polio myelitis, encephalitis, migraine, deafness, diabetes, and traumatic injuries.”
Kudzu is also a desirable fodder for cattle, sheep and goats. Bring in a herd of goats and your kudzu invasion will soon be greatly reduced.
Artisans can make and use or sell baskets made from kudzu vine, or just process the vines for basket-weavers.
Wild artichoke or cardoon can be extremely problematic as an invasive species, but these are also a delicious source of free food. Harvesting the edible parts of the plant will remove the flowers, preventing them from reseeding. The hearts can be eaten, used in dips and recipes or preserved in marinade for future use or sale to gourmet cooks.
Burdock, according to rxlist.com, is used to increase urine flow, kill germs, reduce fever, and “purify” their blood. It is also used to treat colds, cancer, anorexia nervosa, gastrointestinal (GI) complaints, joint pain (rheumatism), gout, bladder infections, complications of syphilis, and skin conditions including acne and psoriasis. Burdock is also used for high blood pressure, “hardening of the arteries” (arteriosclerosis), and liver disease. Some people use burdock to increase sex drive.
Burdock is applied to the skin for dry skin (ichthyosis), acne, psoriasis, and eczema. Burdock root is also used as a food.
One way to stop burdock is to keep cutting it down before it goes to seed to prevent reseeding and spreading. Another way is to build a movable pig enclosure around the problem area and turn loose a couple pigs. They will root up the burdock (and anything else in the area), and then you may plant a competing useful plant in the “tilled and fertilized” soil before moving the pigs to the next problem area. This technique also works with invasive ferns or really, any invasive shrub or runner.
Black locust is seen in many places as a noxious, dangerous invasive, yet the benefits of black locust are numerous. Lumber made from this wood is practically indestructible once seasoned. Their rapid regrowth means they can be easily coppiced for making fenceposts that can be buried directly in the ground and remain unrotted for 50 or more years. It is one of the few fast-growing hardwoods and can grow as much as 26 feet in 3 years, making them the ideal tree for managed woodlots coppiced for firewood or quickly-renewable lumber. They are a major resource for bees (and therefore beekeepers).
Many people eat the blossoms and young seed, but there is some disagreement whether that is wise. However, the seeds are well-liked by northern bobwhite quail, mourning dove, wild turkey, white-tailed deer, eastern cottontail, and squirrels. White-tailed deer also eat the leaves and twigs, according to a university extension service. So the trees can attract edible animals, even if you don’t want to eat the seeds and blossoms.
One way to control the spread of black locust is to plant other fast-growing trees such as poplars, around the edges of the grove. Black locusts like to grow in the open and will not thrive or spread under the canopy of another grove. The one thing you should never do is try to cut them down–they love to be cut and will spring right back up from 10 different spots along the root, making the grove denser than before. Just coppice and enjoy the trees while limiting their spread.
Anywhere an invasive plant grows, there will be a useful plant that will thrive in the same conditions. Clear-cutting the invasive (before it goes to seed) and re-seeding at the beginning of the next growing season with useful plants may help crowd out the unwanted plants.
For smaller invasions that you wish to nip in the bud, try clear-cutting before it bolts and then layering with several thicknesses of cardboard (free behind grocery stores and the like). Make sure the layers overlap well and extend well beyond the edge of the invasion, then weight down with rocks or shovel soil on top to further block light. Eventually, the roots will use up their stored energy and die or be severely crippled. If you plant competing useful plants in the soil covering the cardboard, the cardboard will soften when wet and the useful plants will be able to push through to the soil underneath and become established while the invasive is still struggling for light. Be vigilant about cutting down any invasive that pokes above the soil while the beneficial plant gets established.
There are many ways to deal with invasive plants without resorting to contractors, heavy machinery or poisons that harm the environment.