Buckthorn (Rhamnus frangula) is an invasive weed that can take over the underbrush of a wooded area. Buckthorn also can grow out of hand in the garden or lawn. In fact, in some states, including Minnesota, it is illegal plant some buckthorn varieties, such as European or glossy (also known as alder) buckthorn. Before you get rid of your buckthorn, correctly identify it since it can be confused with many noninvasive plants. In general, buckthorn has egg-shaped leaves with a toothed edge. The wood is brown with a tint of silver. Its 1/4-inch black, red-brown or dark-purple fruits ripen in clusters in late summer or fall.
Pull up small buckthorn seedlings--stems up to 3/8 inch--by hand. Grab the bottom of the stem and pull. Get all the roots. This is easier when the soil is moist. Repeat whenever you see new seedlings growing.
Remove buckthorns that are too large to pull up by hand--usually up to 2-inch stems--with a weed-pulling tool such as a "weed wrench." Secure the wrench end of the tool to the bottom of the stem and pull down on the large handle to lift the buckthorn out of the soil. Again, this is easier when the soil is moist.
Cut down larger buckthorns--2-inch stems or longer--with a saw or lopping shears. Cut right at the ground, then cover with black plastic (or a tin can) to prevent regrowth. Or spray the stump immediately with triclopyr. Spray right on the cut surface. Choose a ready-to-spray herbicide for easy use.
Discard pulled or cut buckthorn weed in the trash. Do not throw it into a garden debris or compost pile.