Amur Corktree
(Phellodendron amurense)
Biological Category
Plants
NY Legal Status
Prohibited
Species Type
Tree
DESCRIPTION
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.
Note: Research for these pages was generated from citations listed. References for specific statements available upon request.
Leaves: 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.
Flowers: Creamy yellow to white flowers in June are arranged in large, terminal clusters.
Fruit/Seed: Amur corktree fruits are round, grape-like clusters of drupes up to half an inch wide which ripen to black in early fall.
Amur corktree was introduced to North America from its native China in the 1850s. The extremely hardy, drought-, cold-, and pollution-tolerant species was commonly sold as a street tree, favored for planting in urban areas. The species is now present in at least 14 states.
Amur cork tree colonizes roadsides, old fields, woodland edges and other waste spaces. Although the species prefers moist, well-drained soil in full sun, it is a good competitor on depauperate, dry sites and can adapt to both alkaline and acid soils.
Female Amurcork trees are capable of producing thousands of seeds a year once mature. Each drupe contains five seeds which require no stratification prior to germination. Light and fire appear to increase germination rates of Amur corktree seedlings. Although no studies have been conducted expressly on the longevity of Amur corktree seeds in the seedbank, the species has a moderately hard endocarp, suggesting seeds may persist as viable propagules for at least several years. Vectors include birds and water.
Established stands of this invasive tree can outcompete native species and change the composition and density of the surrounding vegetation, particularly in early successional habitats. The species has been shown to exhibit allelopathic properties and can inhibit the germination and growth of other vegetation.
There is currently no single optimal biological control agent in use against this species.
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.
Mowing: Mowing, weed whacking or cutting will cause larger individuals to re-sprout. This tactic is more effective when followed up with chemical treatment.
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.
Prescribed Fire: Controlled burns will eliminate seedlings and top kill larger trees.
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.
Cut Stump: A 50% solution of glyphosate applied immediately to cut stems is effective in controlling this species.
Basal Bark: A 25% solution of triclopyr is effective when applied from early fall through winter.
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.
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.
Disposal Methods: Mowed, cut, or pulled Amur cork tree can be composted or chipped so long as management occurred prior to fruiting.
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