Amur Cork Tree

Amur Cork Tree
Phellodendron amurense
Height and form: 30-45’ tall; short trunk and broad branches.
Leaves & stems: Older trunks have distinct thick corky or spongy outer bark; cutting
into the bark reveals bright yellow inner bark. Large, opposite pinnately compound
leaves with 5-11 leaflets, smell somewhat of citrus or disinfectant when crushed.
Leaflets are entire and dark green, turning yellow in fall. Can resprout from
cut-stumps.
Flowers: Both male and female flowers are greenish-yellow, inconspicuous in size,
and found in clusters. June blooming.
Fruits & seeds: Trees are dioecious, producing fruit only on female plants. Fruits are
drupes (fleshy fruit with a single stone), green in color from mid to late summer,
turning black in fall. Fruits remain on trees into winter and may be dispersed by birds.
Legal Classification in Wisconsin: Prohibited Invasive Species
Male cultivars are exempt and are allowed
Identification
•Suppresses and displaces native plant populations.
•Adaptable to different soil types, but preferring moist, well-drained soils.
•Grows in both full sun and under dense shade.
•Reproduces by both seed and by resprouting from stumps.
•Alters soil microorganisms and surrounding vegetation.
•Planted throughout the United States; tolerant of urban areas.
Ecological Threat
Amur Cork Tree
Phellodendron amurense
Height and form: 30-45’ tall; short trunk and broad branches.
Leaves & stems: Older trunks have distinct thick corky or spongy outer bark; cutting
into the bark reveals bright yellow inner bark. Large, opposite pinnately compound
leaves with 5-11 leaflets, smell somewhat of citrus or disinfectant when crushed.
Leaflets are entire and dark green, turning yellow in fall. Can resprout from
cut-stumps.
Flowers: Both male and female flowers are greenish-yellow, inconspicuous in size,
and found in clusters. June blooming.
Fruits & seeds: Trees are dioecious, producing fruit only on female plants. Fruits are
drupes (fleshy fruit with a single stone), green in color from mid to late summer,
turning black in fall. Fruits remain on trees into winter and may be dispersed by birds.
Legal Classification in Wisconsin: Prohibited Invasive Species
Male cultivars are exempt and are allowed
Identification
•Suppresses and displaces native plant populations.
•Adaptable to different soil types, but preferring moist, well-drained soils.
•Grows in both full sun and under dense shade.
•Reproduces by both seed and by resprouting from stumps.
•Alters soil microorganisms and surrounding vegetation.
•Planted throughout the United States; tolerant of urban areas.
Ecological Threat
•Control should prioritize removal of female (fruiting) trees first by girdling
combined with herbicide application.
•Cork tree resprouts vigorously if not treated after cutting.
•Follow up with replanting of desirable species appropriate for the site.
Some control options include:
•All trees larger than 3” can be treated with cut stump, basal bark, girdle, or hack and
squirt methods using systemic herbicides such as triclopyr, glyphosphate, or 2,4-D +
triclopyr and horticultural oil.
•Seedlings can be controlled with a targetted foliar spray of clopyralid (1 oz/gal) or
2,4-D + triclopyr (3-4%) in mid-summer.
To report an invasive species, please visit
http://dnr.wi.gov/topic/Invasives/report.html and follow the reporting instructions.
Control Techniques
Basal Bark: Apply triclopyr (dilute to 12.5% with horticultural oil, or more dilute for
trees with base less than 2” diameter) in a 6-15” wide band around the entire trunk
of the tree and at the root collar at the base of the stem. Only suitable for smaller
trees that don’t yet have corky bark. Avoid this treatment when temperatures are
above 80°F.
Cut Stump: Using loppers, chainsaw, or other suitable tool, cut down the tree. Apply
2,4-D + triclopyr diluted to 12.5% in horticultural oil to the entire cambium (area
just inside the bark) using a sponge or handheld sprayer. Avoid this treatment when
temperatures are above 80°F.
Girdling: Carefully cut a band of bark around the entire tree (1-2” wide for smaller
trees, 6-8” wide for larger trees). This disrupts the flow of sap between the roots and
the crown of the tree. Follow with herbicide application as outlined in the cut stump
treatment to prevent resprouting.
Hack + Squirt: Similar to girdling. Using a hatchet, chainsaw, or other suitable tool,
cut a continuous ring of overlapping notches through the bark around the tree
trunk within 12” of the base. Follow with herbicide application as outlined in the cut
stump treatment.
•Control should prioritize removal of female (fruiting) trees first by girdling
combined with herbicide application.
•Cork tree resprouts vigorously if not treated after cutting.
•Follow up with replanting of desirable species appropriate for the site.
Some control options include:
•All trees larger than 3” can be treated with cut stump, basal bark, girdle, or hack and
squirt methods using systemic herbicides such as triclopyr, glyphosphate, or 2,4-D +
triclopyr and horticultural oil.
•Seedlings can be controlled with a targetted foliar spray of clopyralid (1 oz/gal) or
2,4-D + triclopyr (3-4%) in mid-summer.
To report an invasive species, please visit
http://dnr.wi.gov/topic/Invasives/report.html and follow the reporting instructions.
Control
Basal Bark: Apply triclopyr (dilute to 12.5% with horticultural oil, or more dilute for
trees with base less than 2” diameter) in a 6-15” wide band around the entire trunk
of the tree and at the root collar at the base of the stem. Only suitable for smaller
trees that don’t yet have corky bark. Avoid this treatment when temperatures are
above 80°F.
Cut Stump: Using loppers, chainsaw, or other suitable tool, cut down the tree. Apply
2,4-D + triclopyr diluted to 12.5% in horticultural oil to the entire cambium (area
just inside the bark) using a sponge or handheld sprayer. Avoid this treatment when
temperatures are above 80°F.
Girdling: Carefully cut a band of bark around the entire tree (1-2” wide for smaller
trees, 6-8” wide for larger trees). This disrupts the flow of sap between the roots and
the crown of the tree. Follow with herbicide application as outlined in the cut stump
treatment to prevent resprouting.
Hack + Squirt: Similar to girdling. Using a hatchet, chainsaw, or other suitable tool,
cut a continuous ring of overlapping notches through the bark around the tree
trunk within 12” of the base. Follow with herbicide application as outlined in the cut
stump treatment.
Techniques
Chris Gaetzke
Co-Chair
Lower Chippewa Invasives Partnership
800 Wilson Ave, Room 330
lcinvasives@gmail.com
https://lcinvasives.org/
https://www.facebook.com/pages/Lower-Chippewa-Invasives-Partnership
/228645437257275?fref=ts
715-231-6540
Chris Gaetzke
Co-Chair
Lower Chippewa Invasives Partnership
800 Wilson Ave, Room 330
lcinvasives@gmail.com
https://lcinvasives.org/
https://www.facebook.com/pages/Lower-Chippewa-Invasives-Partnership
/228645437257275?fref=ts
715-231-6540

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