Regulations (pertaining to the Great Lakes) The New York Invasive Species Council assessed F. alnus as having a high risk of causing ecological harm and recommended that its use be prohibited (New York Invasive Species Council 2010). This species is restricted in Wisconsin; it may not be transported, transferred, or introduced into any ecosystem (Bureau of Plant Industry 2012). Frangula alnus is considered an exotic weed by the Illinois Department of Natural Resources; sale of this species within the state is not allowed (Bureau of Environmental Programs 2009). It is listed as a restricted noxious weed in Minnesota and the importation, sale, or transport this plant is illegal (State of Minnesota 2009).
This species is not widespread in the ceded territories governed by the Great Lakes Indian Fish and Wildlife Commission (GLIFWC). The GLIFWC recommends that glossy buckthorn be controlled immediately upon being found. In areas where F. alnus is already present, the GLIFWC categorizes it as capable of having severe ecological impacts and recommends that small, peripheral populations be controlled upon detection and center populations be monitored (Falck and Garske 2003).
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
When treating a large infestation and/or working with limited resources, priority should be given to the largest trees bearing blooms or fruits (Thompson and Luthin 2004). It is important to have a disposal method in place for the portions of the glossy buckthorn that contain fruit. Stems and branches with berries can be destroyed by burning; those without fruit can be left on site to decompose (NRCS 2007). If burning is not an option, fruit should be disposed of off-site (PADCNR n.d.).
Biological
Currently there are no specific biological control agents for this species, but research on more generalized herbivores is ongoing (Chandler et al. 2010).
Physical
Cutting alone will not control this species because it will resprout, regardless of what time of year it was cut (IPAW 2012). When using a physical control method, effort should be made to limit soil disturbance so as not to cause to erosion (Larson 2009).
Individual plants less than 0.5 inch in diameter can be removed by hand. Removing manually is easiest when the soil is sandy or is moist (Michigan Natural Features Inventory 2012). Care must be taken to disturb the soil as little as possible (Buenzow 2010). Plants that are 0.5 inch to 1.5 inch in diameter can be physically removed with a mechanical device- care should be taken to disturb as little of the soil as possible (Buenzow 2010).
Glossy buckthorn can also be controlled through girdling. In this method, cuts are made to the trunk or main stem just above the base, the bark is removed (including the green, cambium layer beneath the bark) (NRCS 2007). The cut should be large enough, about an inch long, to prevent the tree from healing (NRCS 2007). The Illinois Natural History Survey recommends making 2 parallel cut 4-5 inches apart when girdling (Heidorn 2011). This method is most effective when in the summer after the leaves have fully developed or after the leaves have dropped off in the early winter (NRCS 2007). This method is less effective on plants that have many main trunks/main stems (NRCS 2007).
If glossy buckthorn is growing in a grassland or savanna ecosystem, controlled burns may offer long-term control. This method needs to be repeated ever 2-3 years (State of Minnesota 2009). Burns are most effective from April through June and from September through November (Hanson et al. 2012).
Repeated mowing in open areas has been reported to be effective in prevented seedling establishment (Ohio EPA 2001). This method is most effective for plants less than 2 years old. Mowing in early spring and again in fall will help deplete the energy reserves in the root system, deplete the seed bank, and will not interfere with any birds that may use glossy buckthorn for nesting (NRCS 2007).
If glossy buckthorn is present in a managed wetland with a lowered water level, returning the level to its original depth may flood and kill the plants. The impact a changed water level will have on the whole ecosystem should be determined in advance (Roman 2007).
Chemical
Adding dye to herbicides prior to application, will help distinguishes between plants that have and have not been treated (Michigan Natural Features Inventory 2012).
One method is to spray foliage with herbicides such as glyphosate (Accord®, Foresters’ Glypro®, Roundup®, Cornerstone®, Razor®), triclopyr (Garlon 3A®, Garlon 4®, Tahoe 4E®), fluazifop (Fusilade II®), imazapyr, metsulfuron-methyl, 2,4-D, or picloaram to control glossy buckthorn (Division of Forestry 2011, Hanson et al. 2012). Glyphosate will kill any vegetation it comes in contact with and triclopyr will kill broadleaf plants, but will not harm grass if applied properly (State of Minnesota 2009). The best time to use the foliage spray method is between May and November (Hanson et al. 2012).
For plants with stems less than 6 inches in diameter, basal steam treatment, in which an oil-based herbicide is applied directly the bark from the root collar up 12-18 inches, can be used without having to cut down the plant (Buenzow 2010, State of Minnesota 2009). Glyphosate and triclopyr can also be used for this technique (Hanson et al. 2012). Herbicide can be applied with a low-pressure backpack sprayer. Herbicide can be applied any time of year, providing there is access to the ground line; although late fall and winter are preferred because plants are dormant. Glossy buckthorn may leaf out in the spring after a fall or winter herbicide application, but the leaves should senesce as the chemicals are translocated throughout the plant (Buenzow 2010). Basal spraying is the most cost-effective method of controlling populations of glossy buckthorn (Thompson and Luthin 2004).
Both the ester and amine formulations of triclopyr can be used to treat glossy buckthorn; the amine form is safe for use in most wetlands (Larson 2009, Michigan Natural Features Inventory 2012).
Other
Larger trees can be cut near soil level in late summer or early fall. The stumps should then be treated within two hours of being cut with herbicides containing triclopyr. Only the cut surface needs to be treat when using a water-soluble herbicide, but when using an oil-based herbicide, treat the cut surface and the remaining bark (State of Minnesota).
For more detailed information please see:
Midwest Invasive Plant Network Invasive Plant Control Database
The Michigan Department of Natural Resources- Best Control Practices for Glossy Buckthorn
http://mnfi.anr.msu.edu/invasive-species/GlossyBuckthornBCP.pdf
The Pennsylvania Department of Natural Resources- Invasive Exotic Plant Tutorial
http://www.dcnr.state.pa.us/forestry/invasivetutorial/common_glossy_buckthorn_M_C.htm
The Natural Resource Conservation Service- Pest Management for Buckthorn
http://efotg.sc.egov.usda.gov/references/public/MN/797Buckthorn.pdf
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.