- Amur corktree is a member of the Rue family (Rutaceae)
- Amur corktree is a medium sized deciduous, dioecious tree growing up to 50 feet in height, given the right conditions. Its thick, corky bark is a good diagnostic feature, as are the conspicuous grape-like drupes (fruits), emerging towards the end of the summer. A member of the citrus family, its leaves are strongly pungent when crushed.
Dark green, compound leaves are oppositely arranged with five to eleven leaflets. Leaflets are elliptical in shape, up to four and a half inches long, and smell strongly of turpentine when crushed. (5)
Creamy yellow to white flowers in June are arranged in large, terminal clusters. (4)
Amur corktree fruits are round, grape-like clusters of drupes up to half an inch wide which ripen to black in early fall. (1)
Amur corktree is a shade tolerant, prolific seed producer capable of adapting to a variety of soil conditions. Due to its quick growing seedlings, young Amur corktrees can germinate and outcompete understory competition, rapidly converting diverse forests and woodlands to homogeneous stands. Furthermore, Amur corktree is known to be allelopathic, inhibiting the germination of seedlings of other plants and potentially modifying the species dynamics of native forest ecosystems in irreversible ways. (2) One study reports that Amur corktree gains an advantage over native vegetation in areas with high deer concentrations, as these herbivores do not eat this malodorous invasive. (12)
No biological control option is currently available.
Manual or Mechanical Control
Pulling / Digging Up: Hand pulling or digging young plants is effective, though time consuming. Larger plants can re-sprout from root fragments left in soil. (10)
Mowing: Mowing, weed whacking or cutting will cause larger individuals to re-sprout. This tactic is more effective when followed up with chemical treatment. (10)
Girdling: Girdling is an effective method of control if used with a chemical control method such as cut stump application Otherwise, re-sprouting will occur. (10)
Prescribed Fire: Controlled burns will eliminate seedlings and top kill larger trees. (11)
Prescribed Grazing: No information available
Soil Tilling: Not advisable as larger plants can re-sprout from root fragments
Mulching: No information available
Solarization: Not applicable
Hot Foam Spray: No information available
Foliar Spray: A 3-4% solution of glyphosate, triclopyr, or Clopyralid is effective. Always read all instructions on the label. (10)
Cut Stump: A 50% solution of glyphosate applied immediately to cut stems is effective in controlling this species. (11)
Basal Bark: A 25% solution of triclopyr is effective when applied from early fall through winter. (11)
Stem Injection: No information available
Pre-Emergent Spray: No information available
Frill and Spray: Apply a 50% solution of glyphosate or triclopyr to cuts in Amur cork tree’s cambium. (13)
The pesticide application rates and usage herein are recommendations based on research and interviews with land managers. When considering the use of pesticides, it is your responsibility to fully understand the laws, regulations and best practices required to apply pesticides in a responsible manner. At times, the pest you seek to treat may not be listed on a pesticide label, requiring a 2(ee) exemption from NYSDEC. Always thoroughly read the label of any pesticide and consult the NYSDEC or a licensed pesticide applicator.
General management overview and recommendation
As with any other invasive infestation complex, large stands of Amur cork tree are best managed via a combination of mechanical and chemical means. Larger individuals should be treated with a cut stump or basal bark or frill and spray herbicide application, while small individuals can be pulled or sprayed. All managed infestations should be monitored for several years to ensure exhaustion of the seed bank and to monitor for any re-sprouting. Any new seedlings can be hand pulled. New sprouts must be treated with foliar spray or continued re-cut of the new growth.
Post treatment monitoring
Controlled populations should be revisited at least 2 times a season for at least 4 years to ensure exhaustion of the seed bank and to check that no re-sprouting has occurred.
Mowed, cut, or pulled Amur cork tree can be composted or chipped so long as management occurred prior to fruiting.
- Interview with Trillium Invasive Species Management INC