There are a wide variety of non-native invasive plant species that have taken hold in Madison County. These plants cause harm to the environment, as well as potential harm to human, animal, and plant health in the preexisting environment. Some of these damages can be caused by overtaking beneficial native plants in the ecosystem, act as vectors for diseases and other invasive species, such as invasive insects, and are unhealthy or potentially toxic to native animals. In this series, we will discuss identification and control of these prevalent invasive plants.
Identifying Chinese Privet
Chinese privet (scientific name Ligustrum sinense) is an evergreen shrub that originated in China. This shrub can range in size from 6 feet in height and width up to 15 feet in height and width. This invasive plant has small, about 1 to 3 inches in both length and width, oval shaped leaves with smooth edges. These thick, papery leaves are green and glossy on the upper surface, with a pale green lower surface, and a hairy midrib vein. The bark on Chinese privet is smooth, and ranges slightly in color from light gray to light tan or slightly yellow colors. During the summer, usually June and July, this invasive plant blooms with tiny white flowers that appear in clusters at the ends of the branches. Each individual bloom is less than one inch in size, with 4 to 5 fused petals, and they release a foul smell that many people find off-putting. In the late summer and early fall, usually August to September, small black fruits will begin to appear on Chinese privet in groups that almost resemble grape clusters. Each individual fruit is less than an inch in size, and are olive-like in appearance. This invasive plant can live in various environments, tolerating a variety of soil and light conditions. Chinese privet can live in full sun environments, partial shade, and even tolerate only dappled sunlight, and unlike many other invasive species, prefers more basic soils, which often allows it to appear in areas that have been treated or amended for nutrient accessibility, such as pastures, hayfields, and even well tended lawns. This plant is toxic to humans as well, both the fruits and leaves, and can cause symptoms like abdominal pain, nausea, vomiting, diarrhea, low blood pressure, headaches, and weakness and clammy skin that can last up to two or three days. You can view photos of Chinese privet through the NC Extension Gardener Plant Toolbox here.
How It Spreads
Chinese privet was brought into the United States as an ornamental plant in the 1850s, often used to create hedges and as decorative shrubs. Since then, it has grown into an invasive species through much of the southeastern United States, and throughout the midwest. It is often found in bottomlands, low wooded areas, streambanks, and in disturbed areas, such as construction zones or places where the soil has been upturned, such as roadsides and fence rows. The prevalence along roadsides contributes to the spread of this plant, as it can move through suckers that push through disturbed soils, but Chinese privet also spreads over a wide area when seeds are dropped by birds after eating the fruits from this invasive plant. As this plant grows, it forms dense thickets that can choke out more beneficial plants that may be growing in the area. These thickets prevent ground level growth of other plants, which disturbs the forest ecosystem.
Controlling Chinese Privet
Chinese privet is a very difficult plant to completely eradicate from the environment it has invaded unless the infestation is caught in the early stages. If the infestation is well established, it can be controlled, but full removal from the area is difficult and would take many seasons of effort. Depending on the stage of life and the size of the infestation, there are a few potential methods for control.
The first method of controlling Chinese privet is known as mechanical control. Mechanical control involves using methods such as hand pulling, weed-eating, or other similar methods that physically remove the plant from the area. Young seedlings of Chinese privet can be successfully hand-pulled from the environment as long as they are under half an inch in diameter, while specialized tools can be found to help remove stems from this plant that are up to 2 inches in diameter. Unfortunately, cutting or pulling larger sizes of this invasive species are not generally considered effective, and can even further the spread through the disturbing of the soil.
The second method of controlling Chinese privet is known as chemical control. Much like it sounds, chemical control involves using pesticides to cause a chemical reaction in the plants that ends in their death. There are a few different potential methods that can be used to control this invasive shrub in the environment. The first method is called the foliar spray method, which involves spraying a 2 percent solution of triclopyr (a selective herbicide targeting woody plants) mixed with a 0.5 percent non-ionic surfactant over the foliage of the Chinese privet until it is well soaked. Adding this surfactant will help the herbicide stick to the leaves of the invasive plant and provide a more thorough application that is more likely to be effective. This method must be used with caution, as it can cause injury to more beneficial woody plants in the area if they are near the targeted invasive species. Foliar sprays are the most effective during the late fall and early spring as long as the temperature is regularly maintained at 65 degrees Fahrenheit or higher.
Another method known as the cut-stump method is a more targeted approach to the removal of undesirable woody plants. This method is executed by using a solution of 50 percent triclopyr, and spraying it directly on the freshly cut stump, cut off within 6 inches of the ground, of the Chinese privet plant. Be sure that you are applying the herbicide solution on the stump as quickly as possible to the remaining stump to allow for the turgor pressure of the plant’s vascular system to absorb it into the root system. Turgor pressure is caused by the pressure of water within the plant cells that allows the plant to keep its upright and rigid structure, as well as aiding in the flow of nutrients across the expanse of the plant, from the tips of the leaves to the ends of the roots underground. Soak the entire surface of the stump in the herbicide solution until the stump is no longer actively absorbing the solution, which may begin to happen within 3 to 5 minutes of cutting the stump. This method can be used throughout the year, and can be an effective method of control as long as the ground is not frozen. Any treatments conducted to control Chinese privet should be closely monitored for regrowth throughout the year and through the next season of growth to ensure that the infestation is caught early and treated before it begins to come back.
If you have any other questions about identifying or controlling Chinese privet, please contact the Madison County Cooperative Extension Center at peyton_duckett@ncsu.edu, or (828) 649-2411.
Citations
NC Forest Service, & NCDOT. (March 2010). Ligustrum sinense (Chinese Privet).
Invasive Species Leaflet. https://www.ncagr.gov/divisions/nc-forest-service/is02/download?attachment.
NC State Extension. (n.d.). Ligustrum sinense. North Carolina Extension Gardener
Plant Toolbox. https://plants.ces.ncsu.edu/plants/ligustrum-sinense/.
