Common and glossy buckthorn (Rhamnus cathartica and Frangula alnus) are aggressive, invasive deciduous shrubs or small trees that can grow to 25 feet in height. Common buckthorn leaves are a dark glossy green and oval-shaped, with light teeth on the margins. Glossy buckthorn leaves are similar but can be distinguished from common buckthorn by their smooth edges. Leaves of both species remain green late into the fall, when other deciduous species have turned color or dropped their leaves. Common buckthorn has gray to brown bark that is rough when mature; inner bark is yellow, and heartwood is a pinkish-orange. Glossy buckthorn’s bark is thin and gray, slightly fissured and warty.
Buckthorn are able to exist in most soil types and thrive in wet or dry areas. These species are oftentimes found crowding out roadsides, rights-of-way and forested lands in the Midwest, Northeast and portions of the West. They spread from seed dispersed by birds and animals. With their rapid growth and prolific seed production, buckthorns can quickly form expansive and dense thickets, which shade and displace native understory plants, shrubs and tree seedlings.
A low-volume basal treatment using Garlon® 4 Ultra herbicide is one of the most effective treatment methods to control buckthorn. Apply a mixture of 20% to 25% Garlon® 4 Ultra in commercially available basal oil. When treating with basal applications, buckthorn stems should be less than 6 inches in basal diameter. This method is effective throughout the year as long as the stems are not wet.
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