Managing buckthorn: a soybean aphid host

Buckthorn is an over-winter host plant for soybean aphid eggs and the crown rust fungus. This web page describes methods to control buckthorn that may be found in rural windbreaks, river bottoms and woodlands.

Common or European buckthorn (Rhamnus cathartica L.) is an invasive plant which was brought to North America in the 1850s for landscaping and windbreaks. It tolerates a wide range of conditions, quickly out-competes native plants, degrades wildlife habitat and threatens the future of forests, wetlands, and prairies.

Buckthorn is an understory shrub or small tree growing to 25′ high with a spreading, loosely branched crown, and often has multiple stems at the base. Female plants produce purple or black berries in the fall, and seeds are widely dispersed by birds and other wildlife. Female, berry producing plants should be targeted for control first.

Non-chemical Control Methods

Pulling
Small to medium sized trees can be pulled. Monitor area to watch for regrowth from seed and re-sprouting. Buckthorn has a fibrous root system and can be pulled up by hand or tools when small.

Grazing
Goats and other livestock have been used to graze buckthorn. Repeat grazing periods when regrowth occurs is required. Monitor site. Chemical applications may be needed.

Mowing
Repeat mowing required. Monitor regrowth, chemical applications may be needed.

Chemical Control Methods

Cut Stump Treatment
Cut the plant near the ground and treat the cut surface (Cambium/bark ring) immediately with a labeled herbicide.

Low Volume Basal Spray
Wet the bark area around the trunk from ground level up to 12 to 18 inches.

Foliar (Leaf) Application
Spray leaves to wet. May be used on seedlings, small plants, and re-sprouting plants. Avoid spraying non-target plants.

Herbicide Selection

Two herbicides commonly used include glyphosate (a non-selective herbicide) and triclopyr (a selective herbicide active on broadleaf plants). Triclopyr has multiple formulations, including an amine (water-based) and ester (oil-based). The amine is often used for foliar application and the ester for foliar, cut stump and low volume applications. The oil-based formulation will penetrate the bark when water-based formulations will not.

After cutting, mowing, grazing, or herbicide application, re-sprouting and seedling emergence may continue for years. Monitor sites for re-growth annually and retreat accordingly.

When using herbicides, follow label directions, wear recommended protective clothing and avoid contact with non-target plants. The label directions will list plants controlled, areas where the herbicide can be used, and application methods.

Re-establishing Native Vegetation

Many native species can re-establish from existing seed banks and roots if undesirable plants are controlled. Desirable plants can also be seeded or transplanted after controlling invasive species. Planting grasses can reduce establishment of buckthorn seedlings while allowing establishment of desirable native species. An example grass mix may include creeping red fescue, oats or Virginia wild rye after buckthorn removal to prevent erosion. There are also native shrubs including high-bush cranberry, nannyberry, chokecherry, pagoda dogwood, gray dogwood, elderberry, American hazelnut and black chokeberry.

Additional Resources

Buckthorn

Buckthorn ID (video) – U of M Extension

Buckthorn Management First Steps: Reducing the Soybean Aphid Host (video) – U of M Extension

Invasive and Noxious Plants

Control Methods

Native Plants and Trees