What’s Growing Around Your Yard?

Prolific seed production in Japanese Barberry is a competitive advantage. Photo ©Leslie J. Mehrhoff, Bugwood.org

​Do you know what plants are growing on your property? Chances are there are some non-native invasive
plants on borders and wooded areas. Invasive plants are aggressive exotic plants that were introduced either
intentionally for ornamental purposes, or accidentally by hitchhiking on other plants or products. Invasives
thrive in a variety of growing conditions with no natural enemies to control their rapid spread as would occur
in their own place of origin.

Japanese Barberry colonizes woodlands to outcompete native species. Photo ©Leslie J. Mehrhoff, Bugwood.org

The environmental costs of invasives are high – they displace native vegetation and reduce biological
diversity, altering the way plants, animals, soil, and water interact within native ecosystems. And they pose a threat to endangered plant and animal species.

Invasive plants can also be a threat to human health. Japanese barberry (Berberis thunbergii) is a spiny shrub with a twiggy form. Pale yellow flower clusters bloom April-May. Bright red berries develop in late summer and persist into winter. Common in home and commercial landscapes, barberry has escaped cultivation and now grows wildly throughout Connecticut’s woodlands, creating dense thickets that prevent native trees and wild flowers from regenerating. Barberry also poses a risk to human health. A study conducted by the CT Agricultural Experiment Station - Williams, et al 2017, revealed a frightening discovery. Barberry-infested forests had a significantly higher abundance of ticks, with the causal agent responsible for Lyme disease, than in forests free of barberry. The study concluded that managing barberry can significantly reduce the abundance of ticks and the risk of tick-related illness.

The most important thing one can do to control invasives is not to plant them. While Japanese barberry
and other invasives are still sold, there are many excellent native alternatives. Second, it is important to take
action as soon as an invasive is identified in your yard. Once established, many invasives can be difficult to
remove.

The approach used for controlling invasive plants depends on the species and how large the infestation. Early detection is important. Invasive plants like barberry leaf out earlier than our native species. Barberry’s teardrop-shaped leaves are easy to spot in early spring in wooded areas and along edges. Small plants can be easily managed by pulling or digging when the ground is moist, making sure to remove the entire root. Larger plants when cut reveal its bright yellow inner stems and roots. Cut stems can be chemically treated. We refer to the Invasive Plant Management Calendar published by the CT Invasive Plant Working Group (CIPWG) for information on chemical control of barberry. This calendar, along with more information on invasives, is posted on the Newtown Conservation Commission website.

Disposal of invasive plants is an important consideration and depends on the invasive and timing of removal. Barberry, without mature berries/seeds, can be placed in a brush pile. If mature berries are present, plants should be placed in an area where they can be monitored for reseeding or bagged for incineration. Invasives with berries or seeds should never be placed in a compost or brush pile, including the Town Transfer Station.

---