Should You Remove a Norway Maple in Pennsylvania?
You do not have to remove a healthy Norway maple, but a declining one is a strong candidate for replacement, and you should not plant new ones. The Pennsylvania Department of Conservation and Natural Resources (DCNR) includes Norway maple in its invasive plant fact sheets, noting that it spreads from yards into nearby forests, where its extreme shade tolerance lets it grow under an intact canopy, and forests it invades have less wildflower diversity. University of Illinois Extension adds that girdling roots are almost expected on an ailing Norway maple and that verticillium wilt is very often fatal for the species.
The root problem has been measured. In a study published in 1981 in the Journal of Arboriculture, Robert Tate examined 410 street-side Norway maples in Ann Arbor, Michigan, and found that 336 of them, about 82%, had one or more girdling roots, although most were not severely girdled, and he found no clear effect on the crowns at the time. This guide covers how to identify a Norway maple, why it is considered invasive, the problems it brings to a yard, and when removal makes sense.
How Do You Know If It Is a Norway Maple?
Snap a leaf stem. DCNR says the leaves and twigs of Norway maple ooze milky sap when cut or torn, which makes it the only maple in our region with that trait. A native sugar maple will not show that milky sap.
Other features from DCNR's fact sheet:
A large tree with a broad, rounded crown, up to 65 feet tall
Dark green leaves about six inches wide and five inches long, with five to seven lobes
Winged seeds produced in large amounts and spread by wind
Norway maple is a species of maple from Europe that was planted widely as a street and shade tree. DCNR notes it was first introduced to North America by John Bartram of Philadelphia, who received seedlings from London in 1756.
Why Is Norway Maple Considered Invasive?
The problem is less the tree in your yard than its offspring. DCNR explains that Norway maple is usually planted in urban and suburban settings but commonly invades deciduous forests next to suburban areas. Its seeds germinate readily, even in dense shade, and its shade tolerance lets young trees grow deep within an intact forest canopy.
That matters for any property that borders woods. DCNR notes that forests invaded by Norway maple have less wildflower diversity than those dominated by native sugar maple. If you see young maples with milky sap coming up in the woods behind your house, a parent tree nearby is the likely source.
What Problems Do Norway Maples Cause in Yards?
Several issues show up again and again with this species.
Girdling roots
A girdling root is a root that wraps around the trunk or other roots and slowly constricts them. Tate's Ann Arbor study, which followed street trees 54 to 57 years old from 1977 to 1979, found them on 82% of the Norway maples examined, and Illinois Extension's Christopher Enroth writes that when he inspects an ailing Norway maple, circling roots that slowly strangle the trunk are almost expected. If you can see a root wrapping across the base of the trunk, have it looked at before it tightens further.
Surface roots and bare lawns
Enroth notes that maples are notorious for surface roots that create bumpy lawns and break patios. Our posts on whether tree roots can damage driveways or sidewalks and how root systems can damage your foundation cover the risk to hardscape and structures.
Disease
Enroth lists anthracnose, a leaf disease that shows up on Norway maple almost every year, and verticillium wilt, a disease that infects the entire tree and is very often fatal for Norway maple. He also notes the species is native to northern Europe and struggles with scorched leaves in hot, dry weather.
When Does Removing a Norway Maple Make Sense?
Removal is worth considering in these situations:
The tree is declining. Thinning leaves, dead branches or dieback on one side can point to girdling roots or wilt, and a declining tree near the house becomes a hazard.
Roots are damaging something. Lifted sidewalks, cracked patios or roots pressing on a foundation.
It is seeding into woods you care about. DCNR's concern is spread into forests, and removing the seed source stops new seedlings.
You are replanting anyway. If a yard project is already planned, replacing a Norway maple with a native tree is a practical upgrade.
A healthy, well-placed Norway maple that provides shade can stay. In that case, pull seedlings as they appear and keep an eye on the base of the trunk. Our guide to root problems that cause trees to die in PA explains what girdling does over time.
How Do You Control Norway Maple Seedlings?
DCNR recommends pulling seedlings when the soil is moist and digging out larger young plants. For bigger stems, it lists glyphosate or triclopyr applied to the bark or to freshly cut stumps. Follow the product label or hire a licensed applicator for herbicide work.
Removing a mature tree and grinding its stump clears the spot for replanting. Norway maple is not the only popular yard tree now considered a problem in Pennsylvania, and why Bradford pear trees are being removed across PA is another.
What Should You Plant Instead?
DCNR suggests native alternatives including sugar maple, red maple, American basswood, red oak, and tuliptree. It also lists white ash, but the USDA Forest Service reports that emerald ash borer is now in every Pennsylvania county, so ash is a poor choice for new planting.
Give any new tree room. Planting well away from the house, driveway, and overhead lines prevents many of the problems that lead to removal later.
FAQ
Is Norway maple illegal to plant in Pennsylvania?
DCNR includes it in its invasive plant fact sheets, but that listing is not the same as a legal ban. Check with the Pennsylvania Department of Agriculture's noxious weed list for regulated plants, and choose a native maple either way.
How can I tell a Norway maple from a sugar maple?
Break a leaf stem. DCNR says Norway maple oozes milky sap and is the only maple in our region that does.
Are Norway maple roots bad for foundations?
Maples are known for surface roots that lift lawns and patios, according to Illinois Extension. Distance from the house matters most, and a tree growing close to a foundation should be evaluated.
Can a Norway maple with girdling roots be saved?
It depends on how much of the trunk the root encircles. Tate's study found most girdled trees were not severely girdled, and only 5% had more than half of the trunk encircled. Have the root and trunk evaluated before cutting anything.
Why are there so many maple seedlings in my yard?
DCNR says Norway maple produces winged seeds in large amounts that spread by wind and germinate readily, even in dense shade.
When did Norway maple arrive in Pennsylvania?
DCNR credits John Bartram of Philadelphia with introducing it to North America, from seedlings he received from London in 1756.
Norway Maple Removal and Stump Grinding From Brinko Tree Service
Brinko Tree Service, based at 1010 Sunset Blvd in Harrison City, has nearly 20 years of experience serving Westmoreland and Allegheny Counties. When a Norway maple is declining, damaging hardscape, or simply in the way of a new plan, the team provides tree removal and stump grinding so the space is ready for a replacement tree, plus brush chipping and cleanup. Brinko is fully licensed and insured, follows OSHA and ANSI safety regulations with an OSHA safety site supervisor on every job site, and offers free estimates.
Visit Brinko Tree Service or call 412-373-7450 today. Contact us for more information.
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