Common buckthorn (Rhamnus cathartica)
Control
Hand pull: Any time of year when the ground is soft, especially after a rain, hand pull small plants by the base of the stem. Be sure to pull up the entire root system. Hang from a branch to prevent re-rooting. For larger plants, use a Weed Wrench™. Continue to monitor the area every year for new seedlings.
Cut stump: Cut plants back any time of year. Wrap a few layers of burlap or thick plastic over the stump and tie tightly with twine. You will need to check stumps periodically and cut back any new growth.
Cut stump: Cut the plant 4 inches above the ground. Use a drip bottle to apply a 18-21% glyphosate solution to the stump within one hour of cutting. This is best done in late summer through winter when plants are transporting resources to their root systems.
Low volume foliar spray: This method is used for dense populations and best left to a contractor. In the fall, when native plants are losing their leaves, spray a 2% glyphosate or triclopyr solution on the entire leaf surface of the plant. In order to avoid drift to native plants, spray only on calm days.
Photos
Description
Common buckthorn is a deciduous shrub or small tree that can grow to 25 ft. (7.6 m) in height. The bark is dark gray and the inner bark is orange (easily seen when the tree is cut). Twigs are usually tipped with a sharp spine. The leaf arrangement is usually subopposite, but examples of opposite and/or alternate arrangements are commonly found. Leaves are dark green, oval, 1.5 to 3 in. (3.8-7.6 cm) long, slightly serrate with 3 to 4 pairs of curving veins and a somewhat folded tip. Flowering occurs in the spring, when yellow-green, 4-petaled flowers develop in clusters of 2 to 6 near the base of the petioles. Plants are dioecious (male and female flowers occur on separate plants). Fruits are small, black berries that are 0.25 in. (0.6 cm) in diameter. Common buckthorn invades forests, prairies and savannas in the Midwestern United States and can form dense thickets crowding out native shrubs and understory plants. Once established, it is difficult to remove. Common buckthorn is a native of Europe and was introduced into the United States as an ornamental shrub (From http://www.invasive.org/browse/subinfo.cfm?sub=3070)
Buckthorns reproduce by seed but plants can root sprout or regenerate even after they are cut or burned. Plants mature at 5-6 years old. Seed production is prolific. Common buckthorn fruits ripen from August to September while glossy buckthorn fruits ripen earlier—July to August. Seed germination rates are high and germinate well in the shade. Seeds remain viable for at least 2 years.
Birds eat the fruits. Seeds contain a chemical that has a severe laxative effect for birds and thus are readily dispersed by birds and small mammals. The dry fruit is able to float in water from 6-19 days depending on the species. Therefore, in areas of frequent and extensive fall and winter flooding, water dispersal may be significant. Common buckthorn retains their fruit into/throughout the winter. Glossy buckthorn fruit falls to the ground more rapidly after ripening, which makes them less visible to birds and thus less likely to be dispersed long distances.
Class B Noxious Weed
Photos: Sarah Kuebbing, The Nature Conservancy; (c) B. Cook Michigan State University.
Threat
- Birds and mammals feed on buckthorn berries during the winter, aiding in the dispersal of seeds. While buckthorn may benefit from this behavior, the feeding animals do not. Buckthorn berries contain emodin, a natural laxative, that prevents mammals from digesting sugars found in the berries, like this Eastern chipmunk shown above.
- Like many other invasive trees and shrubs, buckthorn leafs out early and retains its leaves into late fall, giving it a much longer advantageous growing season than native plants.
- Buckthorn can increase the amount of nitrogen in the soil, impacting the composition of native species that can grow in the area.
