Norway Maple – Invasive Plant in Sheep’s Clothing

Posted: February 13, 2015

Many people like Norway maple, but it has some characteristics that make it problematic for forest landowners.
Forest Technician, Chuck Kauffman proudly posing next to some other Norway maples we found last fall on Sideling Hill.

Forest Technician, Chuck Kauffman proudly posing next to some other Norway maples we found last fall on Sideling Hill.

Norway maple (Acer platanoides) is a European species. It grows not just in southern Norway but also south to the Mediterranean Sea and east to the Caspian Sea and even to Moscow, Russia!

Here in this country, Norway maple may be one of the most common street trees in Pennsylvania. The reasons for its popularity are clear: vigorous early growth rate, tolerance of urban conditions, ease of transplant, and tolerance of many different soil conditions. Also, many people love the “Crimson King” variety for its maroon-colored leaves. This is often erroneously called red maple.

Unfortunately, there are even more reasons that this tree is undesirable. It has trouble walling off and healing over a wound. These areas usually become rot pockets, reducing durability of the tree. Many people complain about not being able to grow grass under Norway maples because of the dense shade and surface roots. The roots damage paving and sewer lines. They frequently have problems like Verticillium wilt, root rot fungus, and sun scald.

However, the biggest problem to those of us who manage natural landscapes is that it can be tremendously invasive. The fact that it can grow in heavy shade makes it a “sneaky” invasive plant. There are places where a Norway maple was planted decades ago and when you look into the nearby woods, you will just see a few of these seedlings getting started. They bide their time for decades or more just waiting for some neighboring trees to die and then start producing countless seeds themselves.

Recently, we had exactly this occur on Buchanan State Forest near Knobsville, Fulton County. We think we have killed all of these devious trees at that location now. Luckily, it is easy to do with a chainsaw and some concentrated herbicide. Either cut and spray the stump; or girdle and spray.

The Bureau of Forestry has recently unveiled a nearly comprehensive list of new invasive plant factsheets.

This resource is intended to give the public more information to identify and control these plants. Even if you think you know a good bit about invasive plants, time spent with these factsheets will provide some little known insights, especially on species not usually considered potential problems.

Contact Information

Dave Scamardella
  • Forester, PA DCNR Bureau of Forestry