by Bruce Wenning
Common Name: Glossy Buckthorn
Regulations: The importation, distribution, trade, and sale of glossy buckthorn have been banned in Massachusetts effective January 1, 2009 (Massachusetts Prohibited Plant List website, 2012).
Plant Taxonomy: Family Rhamnaceae. Genus Frangula (some people use the genus Rhamnus). Species: Frangula alnus P.Mill. = Rhamnus frangula L.
General Description: Glossy buckthorn is a single stem or at times, multiple stem shrub or small tree that can grow up to approximately 20 feet (McClain, 1996). Leaves are glossy or shiny on top and have a dull green underside. Leaves are also alternate along branches, entire (smooth edges) to obscurely crenulate (leaf edges have small, rounded teeth) (Whitcomb, 1985; Magee and Ahles, 2007). Terminal buds are brown, pubescent and have no bud scales (i.e. naked buds) (Dirr, 1990). Glossy buckthorn is native to Asia, North Africa, and parts of Europe (Dirr, 1990).
Invasive Traits: Glossy buckthorn exhibits
(1) High seed production and good seed viability. Seeds stay viable in the soil bank for two or more years depending upon soil conditions (Gucker, 2008).
(2) Vectors. Seed is dispersed by birds and other berry feeding animals, sometimes over great distances.
(3) Sexual reproduction breeding system. Breeding system is a monoecious condition where both male and female reproductive parts are consolidated into the same flower on the same plant (i.e. perfect flowers). Glossy buckthorn can self-fertilize and produce viable seeds. Therefore, it takes only one glossy buckthorn to produce a colony of reproducing plants if left unchecked.
(4) Vegetative or asexual reproduction (i.e. sprouting). Vegetative reproduction (i.e. sprouting) occurs when stems are cut or broken. Sprouting produces more reproductive stems which give way to more flowers, fruit, and seed than the original uncut or unbroken stems.
(5) Predator avoidance and/or deterrence. Virtually there are no predators feeding on or killing this plant.
(6) The timing of leaf out and of leaf loss. Leaves emerge a little earlier in the spring than some native plants, but this species holds onto its leaves a little longer in the fall than most native plants. This trait allows glossy buckthorn to produce more carbohydrate and other compounds in the leaves by way of photosynthesis and transport these products to the roots for storage (i.e. cold weather storage for better winter survival and spring growth).
(7) Shade/sun tolerance. Glossy buckthorn is shade-tolerant. However, it frequently invades sunny spots which is why it is seen growing in open fields, along field edges, along roads and paths, and any other areas that are sunny.
(8) Time of year of fruiting. This species flowers from April through June and fruits (produces dark purple colored berries containing seed) in July up to mid-October (Zheng et al, 2006; Dirr, 1990; Magee and Ahles, 2007; Gucker, 2008). Glossy buckthorn is insect pollinated.
IPM Control Strategies for Glossy Buckthorn
1. Cultural Controls: Monitor or visually inspect your property for glossy buckthorn. Do this at least every June and September. As stated in Part II, IPM Control Strategies for Exotic Invasive Plants, prevention is a cultural control of great value. Do not plant or encourage the planting of this species. Educating others (e.g. clients or neighbors) about the dangers of this pest is another cultural control of enormous value.
2. Mechanical Controls: Pull, dig, and cut. Pull out easy-to-pull plants. If you can’t hand-pull glossy buckthorn, then you can dig out the plant or pull it out with a Weed Wrench®. Spring or early summer cutting of glossy buckthorn will slow its growth, but may not inhibit flower, fruit, and seed production. Repeated cutting on a monthly cycle will be more effective at stunting the plant and inhibiting fruit and seed (berry) production. Mechanical controls can be done at any time during the year; however, the best times are the months before or during flowering.
3. Biological Control: There are no insects, mites or commercially available disease organisms yet found to be effective biological control agents. Grazing goats are used in more rural areas for glossy buckthorn control.
4. Chemical Controls: The best time for any control option is just before a plant flowers. In addition, the application of herbicides in July, August, and up to mid-September gives maximum chemical control. These are the months that carbohydrates and other plant compounds are being manufactured in the leaves by way of photosynthesis and transported from the leaves to the roots for storage. This downward flow of plant compounds helps facilitate the transport of foliar and stump applied herbicide to the roots during these months for more effective kill. The mechanical control of cutting or mowing is also very effective during these months for the same reason. For example, when you cut the top off any plant the roots naturally respond by pushing up more top growth (sprouting), thus reducing the root reserves (carbohydrates and other growth compounds) and stressing the plant. Every time you cut the top off you force the plant to sprout which reduces the root reserves and weakens the plant.
Suggested chemical control during July, August, and up to mid-September is to cut glossy buckthorn down to one inch from the ground and immediately apply straight glyphosate herbicide to the freshly cut stump using a paint brush or sponge applicator. Roundup ‘poison ivy killer’ works very well. Suggested chemical control in March, April, May, and June is to cut the stump high (six to twelve inches) and let it sprout. Then cut the sprouted plant in July, August, or early September to one inch from the ground and stump-applicate with straight glyphosate herbicide.
A Suggested Glossy Buckthorn Example Using the IPM Procedure
1. Properly identify glossy buckthorn. Educate your neighbors about what you are doing and why.
2. Hand-pull what you physically are able before glossy buckthorn produces berries (seeds); preferably before July.
3. Use a Weed Wrench on hard to pull plants; preferably before July.
4. Plants that prove to be too difficult to remove by way of pulling or digging you can cut down to a one inch stump and immediately apply a glyphosate herbicide to the freshly cut stump using a paint brush or sponge applicator. Stump application is very effective during July, August, and up to mid-September.
If you cannot stump-applicate the hard to pull plants during the summer months, then you can instead cut the plant six to twelve inches from the ground before it starts to produce berries (seeds) in July. After the taller stump has re-sprouted, you cut it to one inch above the ground and immediately apply glyphosate herbicide to the freshly cut stump. Allowing the stump to re-sprout during the summer months draws carbohydrate and other growth compounds from the roots and depletes some of the root energy making herbicide kill more effective.
5. Foliar application of glyphosate works best on multi-stemmed glossy buckthorn that was repeatedly cut for many years without chemical control follow up or was not removed by digging. Foliar application works best between July and mid-September. Foliar application transports the herbicide from the leaves to the roots. If glossy buckthorn has many stems and is quite large, it may take one to two years for complete kill after one foliar application because multiple stemmed specimens generally have a very large root system. Foliar application enters the leaves more easily during humid weather because the leaf cuticle/wax layer is thinner making the leaf more absorbent to the foliar – applied herbicide (Ware, 1996). Individuals contemplating using chemical control of glossy buckthorn in or near wetlands must use a wetland approved herbicide. It’s the law.
6. Cold weather stump application (November through February; mean temperatures of 15.8 to 46.4 Farenheit) (Reinartz, 1997) reduces the risk of contaminating non-target plants. University of Wisconsin researcher, James Reinartz (1997), tested cold weather stump application using 25% concentration of glyphosate herbicide on glossy buckthorn and obtained 92 to 100% control. I have used straight glyphosate concentration on freshly cut glossy buckthorn stumps and obtained a 98 to 100% kill from November through January. Cold weather stump application frees up time to control glossy buckthorn when there is no available time to do so during the summer months. Cold weather stump application is especially useful on overgrown glossy buckthorn individuals or stands.
7. The above suggested example may be modified to suit existing site conditions and the level of glossy buckthorn infestation.
To learn more about glossy buckthorn visit: www.invasive.org.
Dirr, M. A. 1990. Manual of Woody Landscape plants. Their Identification, Ornamental Characteristics, Culture, Propagation and Uses. Stipes Publishing, Champaign, Illinois.
Gucker, C. L. 2008. Frangula alnus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/[2013, June 30]. Accessed 3 August 2011.
Magee, D. W. and H. E. Ahles. 2007. Flora of The Northeast. 2nd ed. University of Massachusetts Press, Amherst.
McLain, B. 1996. Rhamnus frangula. Smooth or Glossy Buckthorn. P.65 in J. M. Randall and J. Marinelli, eds. Invasive Plants. Weeds of the Global Garden. Handbook # 149. Brooklyn Botanic Garden, Brooklyn, New York.
Reinartz, J. A. 1997. Controlling glossy buckthorn (Rhamnus frangula L.) with winter herbicide treatments of cut stumps. Natural Areas Journal 17: 38 – 41.
Ware, G. W. 1996. Complete Guide to Pest Control. 3rd ed. Thomson Publications, Fresno, California.
Whitcomb, C. E. 1985. Know It and Grow It II: A Guide to the Identification and use of Landscape Plants. Lacebark Publications, Stillwater, Oklahoma.
Zheng, H., Y. Wu, J. Ding, D. Binion, W. Fu and R. Reardon. 2006. Invasive Plants of Asian Origin Established in the United States and Their Natural Enemies. Volume 2. U. S. Department of Agriculture Forest Health Technology Enterprise Team, FHTET 2005 – 15, Morgantown, West Virginia, 175p.
For additional information about exotic invasives, refer to Bruce’s article: “Controlling Small Scale Infestations of Exotic Invasive Plant Species: Ecological and IPM Information for Landscapers and Homeowners.”
Individual Exotic Invasive Plant Fact Sheets:
About the Author
Bruce Wenning has university degrees in plant pathology and entomology and is an ELA Board member and regular contributor to the ELA Newsletter. Bruce also spearheads the effort to expand ELA’s website content. Watch for his upcoming articles with information about individual invasive species. He is a horticulturist at The Country Club, Brookline, MA where he continues his battle with exotic invasive plant species.