Invasive Tree: Buckthorn

Why is buckthorn a problem?

Buckthorn has been sold for years as an ornamental hedge; has dense branches; grows new leaves early in spring; and holds onto its leaves late into the fall. In the woods, dense buckthorn thickets can prevent light from reaching wildflowers and tree seedlings for the entire growing season. Without light, these native plants and trees eventually die.

Buckthorn leaves
Buckthorn has deep-green, oval-shaped leaves approximately two inches long.

How do I recognize it?

Buckthorn is a small tree reaching 10- to 25-feet in height with deep-green, oval-shaped leaves approximately two inches long. The outer bark is very dark and, when cut, the inner bark is yellowish-orange. Buckthorn branches also end in a small thorn. Buckthorn has separate male and female plants, and only the female plants produce seed.

Where does it grow?

Buckthorn is a serious invader of wooded areas. It also commonly invades hedgerows, gradually spreading outward into fields.

How does it spread?

Many bird species eat the buckthorn fruits and deposit the seeds throughout the woods and beyond.

How do I control it?

Herbicides are the best means to control buckthorn and one of the most effective is triclopyr (ester version) at 8 to 12% active ingredient.

Men cutting buckthorn in woods
When treating buckthorn, tip all the cut shrubs to one side (shown here), then treat the stumps with herbicide before cutting another section of shrubs.

Herbicide can be applied in one of two methods: basal bark or cut-and-herbicide.

In the basal bark method, herbicide is applied in a six-inch band around the entire trunk. As an oil-based herbicide, triclopyr is able to penetrate through the bark.

The cut-and-herbicide method requires first cutting buckthorn down, then applying herbicide to the stump. Cut-and-herbicide can be a more efficient use of chemical, produce immediate visual results, and minimize overspray.

When using the cut-and-herbicide method, it can be very easy to overlook stumps or accidentally cover them with cut brush. So the most efficient way to treat a large patch of buckthorn is to work in concentric circles (like circles on a target) around the patch. Begin by cutting one circle around the patch, tipping all of the shrubs to the outside. After one circle is cut, treat the stumps before they are covered by the next circle you cut.

This is your best guarantee that you will cut and treat every plant and always have room to tip cut brush out of your way.