Aliens in Your Yard!:
Common Buckthorn (Rhamnus cathartica)
Why, Where, When, Which, and How to Eradicate

Prepared by Laura Zigmanth, ecoChic landscape design

Member, Healthy Lawns and Gardens Technical Advisory Committee

LauraZigmanth@ecochiclandscape.com

Why:

►   Buckthorn changes soils by aggressively taking up more water than its plant neighbors, denying them resources for growth and vitality

• the homeowner pays more to water to landscape plants more
• the homeowner pays more to remove both in time and resources

►   Buckthorn leafs out earlier in spring and loses leaves later in fall, shading out neighboring bulbs, perennials and wildflowers, shrubs, and small trees

►   Buckthorn fruit and seeds provide no nutritional value to birds and other desired wildlife; in fact, the seeds induces a laxative effect (except for starlings, below)

►   Buckthorn can grow in a variety of soils and conditions, outcompeting its rivals

►   Buckthorn is a highly effective competitor in the landscape and forms thickets that diminish soil moisture, biodiversity, and wildlife habitat throughout the state

Where:

►   Common Buckthorn used to be sold in the nursery trade and has been established in the landscape throughout the state

►   Birds eat the fruit and quickly deposit the seeds where they congregate

• along fence rows
• under utility lines
• next to wooded areas
• in naturalized areas where birds feel safe
• back in the corner of yards that homeowners often neglect

►   Starlings seem to have an ecological and evolutionary relationship: if starlings are present in the garden, there is probably a buckthorn presence

►   Some forms of buckthorn cultivars are still sold in the trade (i.e. the columnar form) and offspring may revert back to the straight species

►   Buckthorn isn’t often seen in bird-unfriendly gardens unless planted (above):

• highly manicured lawns
• non-native shrubs with little cover or a food source

When:

►   Birds resort to seed and fruit feeding when their primary source of food (insects and other macro-invertebrates) diminish in the fall

►   Buckthorn drops seed directly below from the parent, causing thickets to form

►   Seedlings begin to sprout early in spring, depending upon amount of sun

►   Seedlings may sprout in late summer if there are berries

Which:

►   There are 2 major forms of invasive Buckthorn, Common and Glossy

• Description of Common
  • large shrub or small tree up to 20-25 feet tall, grows in dense thickets
  • alternate, smooth (not hairy) oval leaves with toothed edges, 3-4 pairs of semi-parallel veins, dark green
  • thorns at twig tips
  • mature plants have rough and peeling bark, reddish brown and flaky, white lenticels and similar to cherry bark
  • inner bark stays bright yellow-orange
  • buckthorn is dioecious — male and female plants with separate flowers
  • flowers in spring in dense clusters of 2-6 yellow-green, 4-petalled flowers that emerge from stems near the base of leaves
  • pea-sized red-to-purple black berries at the base of leaves ripen in late summer and fall

• Description of Glossy
  • similar to Common
  • no thorns, glossy leaves that are hairy underneath, leaves not toothed, no thorns
• Both are similar to native buckthorn and several types of cherry; consult a botanist if there are questions

How to Eradicate:

►   Easiest –

• Pull seedlings in the spring
• Dig up small saplings, roots and all

►   More difficult — larger shrubs and trees — chemical options

• Cutting the stem and treating immediately with herbicide
• Consult a professional for appropriate herbicides and their use
• Act in late summer and fall when the plant begins to send sap and nutrients to the roots
• Treating in the spring will do little good and probably have to be retreated later in the year

►   Most difficult — non-chemical methods

• Girdle (slicing the bark about 1/2″ deep) the plant by cutting the stems between December and March
• Cutting off the berries

What else?

►   Monitor monitor monitor

►   Educate your neighbors and any yard care professionals

►   Replant with hardy shrubs and small trees to crowd out the thugs

►   Discourage starlings, promote native birds

Download Buchthorn Homeowner Guide