Buckthorn management

picutre of buckthorn leaves on branches with text buckthorn is a real threat to our forests

How much buckthorn you have will affect your treatment plan.

Buckthorn management is a multi-year commitment. Most viable seeds in the soil germinate within two years. Your plan will depend on how much time you have and how dense your buckthorn is. Additional seeds can be introduced to the site by birds or other wildlife. For just a few small plants your plan may be as simple as a weekend of pulling buckthorn seedlings and regularly checking to see if new plants have taken root each year.

For larger buckthorn infestations the first part of your plan should be to remove all of the berry producing buckthorn on your property. This would also be a good time to work with your neighbors to remove berry producing buckthorn from their land too. Once you have controlled berry producing plants you have limited the ability of the buckthorn to expand.

Once your area has no more berry producing buckthorn you can begin to focus on the goal of removing all the buckthorn on your property. If your buckthorn is more like a jungle than a few shrubs you will likely want to plan on removing the buckthorn in sections. Begin removing the buckthorn from one section of your property and set a reasonable goal for the year, remove more and more buckthorn each year until it is eradicated. Start removing buckthorn from sections with to the fewest buckthorn plants to keep those areas unimpaired.

Once all buckthorn has been removed from your land, plan on walking your property at least once a year to find and remove new buckthorn plants. The best time to find buckthorn is fall and early spring when most plants other than buckthorn will be without leaves. Managing buckthorn on your land is an ongoing process, staying vigilant and scouting for new seedlings will reduce your long term workload of removing established buckthorn.

Removing buckthorn

How you remove buckthorn depends on size, location and resources

Plants with stems less than two inches

If less than 3/8 inch in diameter, plants can be removed by hand. Small seedlings can be pulled and will not re-sprout. If greater than 3/8 inch, use a hand tool that pulls the shrub out, such as an "Uprooter" or "Root Talon". Removing by hand is easier if the soil is moist. Before you pull or dig buckthorn out of your soil, Contact Gopher State One Call to ensure there are no buried utilities in the area. Hand-pulling tools can cause soil disturbance so work to minimize soil disturbance and tap soil and native plants back into place after pulling buckthorn plants. Disturbed soil will result in increased seed germination.

If pulling individual plants is impractical, spray foliage of short buckthorn or seedlings with a herbicide. Glyphosate one brand name is Roundup) will kill all actively growing vegetation on which it is sprayed. Triclopyr will kill broadleaf plants and will not harm grasses when applied properly. If you wish to use a cutting method, see the section below.

Plants with stems more than two inches

Buckthorn plants that are two inches in diameter or larger are best controlled by cutting the stem at the soil surface and then covering or treating the stump to prevent re-sprouting. Cutting can be effectively done with hand tools (for a few plants), chain saws or brush cutters.

When to treat buckthorn

The most effective time to cut and chemically treat the stumps is in late summer and throughout the fall. Avoid treating buckthorn in May and June when the tree is putting out leaves as the herbicide will be less effective at this time then during the rest of the year.

You can chemically treat buckthorn throughout the fall and winter. Follow herbicide label instructions regarding temperatures at which the herbicide can be applied. Water-soluble herbicides like glyphosate (Rodeo, etc.) or triclopyr amine (Garlon 3A/Vastlan, many brush killers, etc.) can be applied to cut stumps when the temperature is above freezing (32 deg. F). Oil-based products of triclopyr ester (Garlon 4, Pathfinder II) can be applied when the temperature is below freezing (below 32 deg. F).

Herbicide treatment options

Chemical control options for cut stumps include treating the stump immediately after cutting (within 2 hours) with a herbicide containing triclopyr (Garlon 3A/Vastlan, Garlon 4, or other brush killers with triclopyr) or glyphosate to prevent re-sprouting. Always follow label instructions for herbicides. Refer to the herbicide table in the additional resources for more information.

Herbicides can be applied to cut stumps with a paint-brush, wick applicator such as a dauber or "buckthorn blaster", or a low volume sprayer. When using water-soluble herbicide products like most brush killers, Garlon 3A/Vastlan, or any of the glyphosate products, treat only the cut surface. When using oil-based products like Garlon 4 or Pathfinder II, treat the cut surface and the remaining bark to the ground line.

In cases where more than a few plants are treated, add an indicator dye such as Mark-It Blue (available where pesticides are sold) to the herbicide to mark cut stumps you have sprayed. Colored flags can also help mark cut stumps. When buckthorn is cut, the stumps are easily covered and lost under cut brush.

For basal stem treatment, a method that applies chemical through the bark, low volume spray applications can be made with Garlon 4 and similar oil-based products. This application method uses triclopyr ester mixed with an oil diluent ( i.e. Bark Oil Blue, kerosene or diesel oil) applied directly to the bark of buckthorn from the root collar up about 12-18 inches. This treatment works best on stems less than 2-3 inches in diameter. An ultra low volume spray wand should be used to minimize herbicide use and reduce the potential for non-target injury. Buckthorn treated in this fashion should be left standing until dead and cut at a later date.

Are you treating buckthorn near water?

Common buckthorn generally does not grow below the ordinary high water level, but if it is growing there please contact the Minnesota Department of Natural Resources Aquatic Pesticide Enforcement Specialist before treatments. If you are treating buckthorn near water, use an herbicide labeled for aquatic use. There are formulations of glyphosate (brand name examples Rodeo and AquaNeat) and triclopyr (Garlon 3A, Element 3A) labeled for aquatic use. As with anytime you are treating buckthorn, take care to apply the herbicide only to the cut stump of the tree and not to surrounding vegetation.

Non-chemical treatment options

Cut the stem of the plant a few inches above the soil. Cutting can be effectively done with hand tools (for a few plants), chain saws or brush cutters. Cover the cut stump with a tin can or black plastic (such as a "Buckthorn Baggie") to prevent re-sprouting. After cutting the tree, apply the can or plastic over the cut stump and root flare. Use nails to affix the can or a zip tie to affix the black plastic. Leave in place for at least two summers. Check plants regularly to ensure no new growth is escaping the can or plastic cover.

A newer technique called “critical period cutting” (or “high cut” or “high stump” method) involves cutting the tree while leaving a tall stump and then revisiting the tree over time and continuously removing any regrowth until the tree dies. First cut the tree in the spring after all the leaves have emerged, leaving a stump that is 4 to 5 feet tall. Remove all branches and leaves. Return to the tree in September or October and remove any new growth (leaves, branches, stems, etc.) on the cut stump. Visit the tree again the next year after spring leaf-out and remove any new growth. In future visits, continue to remove any regrowth until the tree has died. Projects following this method have observed buckthorn dying two years after initially cut.

Long-term buckthorn management

Tackling your buckthorn will be an ongoing endeavor, requiring regular follow-up

Follow-up control of seedlings that emerge after initial control efforts is important on all sites. With no follow-up control, buckthorn will come back. Follow-up control options include treating the buckthorn seedlings and samplings using the pulling, cutting, and chemical methods described above. Fire also offers a long-term management option in grassland or savanna cover-types. Burning will need to be done every two to three years.

After buckthorn control, many sites will benefit from replanting of desirable tree, shrub, and herbaceous species. This will minimize bare ground which is often colonized by invasive species. The DNR's Restore Your Shore resource may help you to find the right plants for your location. The University of Minnesota recommends planting grass mixes such as red fescue, oats or Virginia wild rye and native shrubs including as high-bush cranberry, nannyberry, chokecherry, pagoda dogwood, gray dogwood, elderberry, American hazelnut and black chokeberry.

By managing your buckthorn you are helping protect Minnesota's woods, waters and grasslands for wildlife and people to enjoy.

Disposing of cut buckthorn

Buckthorn is regulated by the Minnesota Department of Agriculture as a Restricted Noxious Weed. Please review the Minnesota Department of Agriculture's Guide to Removal and Disposal of Noxious Weeds in Minnesota for thorough guidance on disposal.

With all invasive plants, it is preferred to keep the plant material on site when possible to reduce the chance of spreading seeds to new areas.

If you need to move cut buckthorn off-site, use this locator service provided by MPCA to find yard waste composting facilities near you. Contact the facility manager to find out if they accept noxious weed materials and if they follow the national Seal of Testing Assurance standards. Only some facilities hold compost at a temperature of 131°F for at least 15 days, which is required to destroy noxious weed seeds during the composting process. Some cities also have buckthorn-specific disposal opportunities.

At some sites, chipping the buckthorn stems may be an option, but be aware that chipping does not destroy buckthorn seeds. To prevent the spread of buckthorn, wood chips from fruiting plants should be kept on-site where they could be piled, burned, or spread in an area where any seedlings that sprout could be removed. Alternatively, the wood chips could be sent to yard waste disposal facilities equipped to take buckthorn in seed.

In remote sites, consider obtaining local burn permits and burning piles of cut brush in the winter when the ground is covered in snow.

Contact your local County Agricultural Inspector for additional disposal suggestions in your county.

Landowner assistance

The DNR generally does not have funding to assist landowners with buckthorn removal on urban or suburban properties. If you are looking for assistance with buckthorn on a rural property, contact the DNR forester for your area, who can provide technical assistance and information on cost-share programs. Anyone can contact their local Soil and Water Conservation District to see if they have technical assistance and funding available in their area. View the general terrestrial invasive species assistance opportunities webpage for other potential sources of funding and advice. For additional questions regarding buckthorn management contact the DNR Info Center.

Additional resources

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