Buckthorn Management

Identification of Buckthorn
 

Common or European buckthorn (Rhamnus cathartica)

Form: A large, suckering shrub or small low branching tree growing 20 - 30 feet tall and 10 inches in diameter. 
Leaf: Opposite or partially alternate, oval or egg-shaped with finely-tooth edges, 2 to 3 inches long, dull to glossy, dark green. 3-5 pair curved leaf veins. Leaves stay dark green and on the tree late into autumn.
Bark: Smooth when young, shiny gray to reddish brown with numerous lenticels, later becoming dark gray and scaly; large specimens become rectangular blocky, inner bark is yellow.
Twig: Slender stiff, reddish brown, later with exfoliating gray layer, many end in a sharp thorn; buds, scaly, ovate, pointed, ¼ inch, reddish brown to dark brown.
Flower: Small, yellow-green, 4 petals, in small clusters, appearing in spring.
Fruit: Berry-like, ¼ inch round, shiny black when ripe in late summer.

Glossy Buckthorn (Frangula alnus)

Form: Upright shrub or small tree (to 20 feet) with a spreading, open crown, often multiple stems at the base.
Leaf: Alternate, oval, smooth, toothless edges, 2 to 4 inches long, 8-9 pair of leaf veins, veins are parallel but near edges of leaf turn    and follow the edge, shiny green. Leaves stay green late into fall.
Bark: Smooth gray-brown with a few obvious slightly raised lenticels, may become shallowly cracked on larger stems.
Twig: Slender, reddish brown with gray pubescence, buds naked and tan with fuzz; 3 bundle scars; lacking thorns.
Flower: Very small and inconspicuous, pale yellow-green, bell-shaped, appearing in leaf axils in late spring after the leaves.
Fruit: Berry-like, ¼ inch round, at first red but later turning black, ripens in late summer.

Additional Resources:

University of Minnesota Extension
Minnesota DNR
Minnesota Department of Agriculture

Removal of Buckthorn 

Controlling buckthorn is a labor intensive activity. Effective buckthorn control requires a combination of mechanical and chemical removal strategies, followed by annual monitoring and eventual replanting of the area with native trees, shrubs and wildflowers. Please remember that simply cutting down buckthorn will result in vigorous resprouting if no other control measures are implemented.

Seedlings and Small Individual Trees

• Remove by hand if plant is less than 3/8 inches in diameter. Small seedlings can be pulled and will not re-sprout.
• Remove with hand tool such as a root extractor if plant is greater than 3/8 inches in diameter.  Root extractors may remove buckthorn stems up to 2.5 inches in diameter.  A root extractor or similar tool can cause some soil disturbance so extra care is needed on sensitive sites or steep slopes. Removing by hand root extractor is easier when soil is moist.
• If removing individual plants is impractical, spray foliage with a herbicide:
  • Herbicides containing the active ingredient glyphosate will kill all actively growing vegetation on which they are applied.
  • Herbicides containing the active ingredient triclopyr will kill broadleaf plants and woody vegetation and will not harm grasses when applied properly.

Large trees

For buckthorm 2 inches in diameter or larger, cut stem at soil surface and then cover or treat the stump to prevent re-sprouting.  

• Cut buckthorn with hand tools, chain saws or brush cutters.
• Prevent buckthorn re-sprouting! 
  • Non-Chemical options to prevent buckthorn re-sprouts include covering stumps with a tin can or black plastic for 2 years.
  • Chemical options to prevent buckthorn re-sprouts include herbicides containing the active ingredient glyphosate or triclopyr
    • Check with your local garden, home centers and hardware stores for herbicides containing these active ingredients.
       
• Apply recommended herbicides to cut stumps with a paint-brush, wick applicator or a low volume sprayer.
• Herbicides should be applied in a timely manner (best results are obtained when applying herbicide as soon as possible after cutting.)
  • When using water-soluble herbicide products like Ortho Brush-B-Gon, Garlon 3A, or any of the Glyphosate products, treat only the cut surface.
  • When using oil-based products like Garlon 4, 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 (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 can be left standing or cut at a later date.

Additional Resources

Buckthorn video #1
Buckthorn video #2
Buckthorn video #3

Buckthorn Disposal Program

In an effort to encourage residents to control buckthorn on their property, the City of Eagan, Forestry Division has established a Buckthorn Disposal Program.  Buckthorn disposal is a seasonal service offered to the residents of the City of Eagan beginning end of June – August.  This program is for the management of buckthorn only, however, residents can include prickly ash and exotic honeysuckle for disposal.  The forestry crew will pick up, chip and properly dispose the buckthorn residents remove from their property.  The City does not pick up buckthorn or other, invasive plant material cut by contractors.

Residents should contact the This email address is being protected from spambots. You need JavaScript enabled to view it. or by phone 651) 675-5300 to set up a required, one-time, site visit before conducting any buckthorn removal.  Site visits begin when weather permits.  Previous participants should review program guidelines.

During the site visit, the tree inspector will:

• Assist residents with identification of buckthorn and other woody vegetation on the property.
• Discuss buckthorn control techniques and woodland restoration options.
• Determine where to stack the cut buckthorn
• Determine how to stack the buckthorn for easy pick-up by Forestry Staff
• Schedule a pick-up date.

After the site visit with the Tree Inspector,

• The city forestry crew picks up cut neatly stacked buckthorn, by appointment only.
• Disposal appointments are coordinated by the This email address is being protected from spambots. You need JavaScript enabled to view it.
• Buckthorn is picked up by forestry crews on Monday, seasonally May – August.
• Disposal appointments are limited to 10 per Monday.
• Please call early as Monday pick-ups are typically scheduled several weeks in advance.
• Do not stack cut buckthorn near city streets until a pick-up date has been scheduled and confirmed.

Reminders:

• The property owner must schedule a site visit, prior to participation in the program.
• Buckthorn and other approved invasive plants cut by the residents must be neatly stacked in a single row with cut ends facing the street and placed behind the curb.
• Exact location will be determined during the required site visit.
• Buckthorn brush shall not be stacked in the street.
• NO cut buckthorn with intact roots and soil will be accepted.  Roots and soil can damage and shorten the life of disposal equipment.
• NO species other than buckthorn – exceptions exotic honeysuckle, grape vine, and prickly ash.
• NO tree trimmings, shrub trimmings, yard waste, scrap lumber, or dead logs will be accepted.
• Any material not in accordance with these guidelines will be left on site and cleaned up at homeowner’s expense.  The city will notify the owner in writing of guideline violation(s).
• Additional standards may be added as deemed necessary by the City.
• This program is intended to assist residential property owners. We DO NOT pick-up buckthorn removed by contractors; it is the contractor’s responsibility to dispose of the buckthorn they cut.
• Buckthorn disposal is a seasonal service offered to the residents of the City of Eagan during the months of May - August, depending upon staff availability and weather.
• Buckthorn pickups will occur on Mondays only (weather permitting, holidays excluded) and must be scheduled in advance.  Call (651) 675-5300 or e-mail the This email address is being protected from spambots. You need JavaScript enabled to view it. for details.

Life After Buckthorn

After buckthorn control, many sites may require replanting of desirable tree, shrub, and herbaceous species.  Removing buckthorn will not only benefit the environment but it provides opportunities for you to re-design your landscape, beautify an area, and create wildlife habitat. 

If you are re-planting in the same places buckthorn once grew, the soil will benefit if you wait one or two years before re-planting other trees and shrubs. 

Visit the Tree Planting Resources page as well as local nurseries, Minnesota extension service, Department of Natural Resources, or Department of Agriculture for a list of tree and shrub species adapted for our area.  

What not to do:

Do not cleanup and remove litter from forest floor like fallen leaves and branches.  Debris on the forest floor is critical and essential to the health of the forest.  Litter regulates moisture, prevents erosion, provides wildlife with habitat, and deposits essential nutrients back into the soil.  Fallen branches and dead trees should only be removed if they pose a threat to safety.  Large limbs provide habitat for wildlife and are vital to the nutrient cycle.

Please do not revegetate the forest floor with grass seed or sod.  Turf grasses and mature trees are intense competitors for limited moisture and nutrients.  Aside from depriving trees of water and nutrients, turf encourages mowing.  Mowing around trees can be detrimental if the mower is continuously banged up against the stem.  This damages the tree’s conductive tissue and can lead to death.

Licensed Tree Contractors

Is the buckthorn removal project too large?  Visit the Licensed Tree Contractor Page for hiring options.