What is Common buckthorn?
Common buckthorn and glossy buckthorn are shade and drought tolerant plants that can easily and rapidly grow in a wide range of habitats. Both species were introduced to North America as ornamental shrubs.
Why are they a problem?
Common and glossy buckthorn, as non-native species, are able to outcompete native plants, harming the environment by reducing biodiversity, degrading the quality of wildlife habitat, affecting soil quality, and impacting a wide range of industries.
Their presence can change the nitrogen composition of soil, making it harder for other species to survive. These changes can even have long-lasting effects even after the invasive plants have been removed. They have even been shown to negatively affect some native songbird populations.
Nesting birds in buckthorn are more susceptible to predators as the plants have low branch heights and lack protective thorns such as those found on hawthorns and native rose species. Common buckthorn develops its leaves weeks before native species and loses them weeks after, enabling them to outcompete native species for sunlight.
How to Identify common and glossy buckthorn
Glossy buckthorn – also known as alder buckthorn – can be differentiated from common buckthorn by its untoothed leaves. Common buckthorn is typically found in woodlands and open fields, while glossy buckthorn most commonly invades wetland communities. Common buckthorn blooms May through June during leaf expansion.
It produces black fruits that ripen in August through September. Glossy buckthorn blooms after leaf expansion in late May through September, and can blossom on the current season’s growth. Its fruits are initially red and turn black as they ripen in July through August.
How to manage Common and Glossy Buckthorn
It can take many years to ensure that the population of these invasive plants has been eliminated or is under control. Experience has shown that neighbors and local governments working together to develop a long-term regional management plan have the greatest success in reducing these species over time. The most successful management plans have emphasized native species restoration following treatments as this can reduce new infestations.
Removing invasive buckthorn can be accomplished in a number of ways:
- uprooting small diameter buckthorn plants using a root extractor or similar tool can be effective on smaller stands. Care should be taken to minimize disturbance to soil and adjacent plants, as this can lead to more invasive species becoming established. Uprooting is effective in controlling buckthorns at low densities, or new infestations along trails, roads, and woodland edges;
- early-spring controlled burns can be useful in controlling seedlings in large forests and woodlots with dense populations. Fire is not a stand-alone management option and usually works best in conjunction with herbicide applications and uprooting. Be sure to check with local authorities regarding control burning practices and regulations;
- cutting or mowing can reduce plant size and stem density but will need to be done at least twice in one season (June and August). As they will re-sprout, treatments must be repeated for 2 or 3 successive years;
- large stems can be girdled and re-sprouts clipped as they emerge. Parallel cuts should be made cutting through the bark slightly deeper than the cambium, and the outer bark removed;
- Herbicides can be administered in a number of ways. Foliar, stem injection, basal bark and cut-stem application of herbicides that translocate their active ingredients into the root system can be very effective. Foliar treatments work best on seedlings and immature plants and should be applied early in the growing season.
- Stem injections, basal bark and cut-stem treatments work better on mature plants and can be applied during the late fall when buckthorn is easy to identify. Treatments will need to be administered for several growing seasons until the population is eliminated or controlled. Check with us for assistance and recommendations for using herbicides.