Verticillium wilt often deadly to Crimson King maples

Q. My Crimson King maple is 20 years old. Last year, it dropped its leaves early in August. This year, only one-third of it leafed out. What is wrong? Can I save it?

Dale from Canfield

A. A Crimson King maple is actually a cultivar of Norway maple (Acer platanoides). This tree is native to Europe. It prefers cooler climates. At most, it gets to 40 feet here in the Mahoning Valley. Some people have great luck with it; others have many challenges. It depends on the location, the soil and much more.

This tree has a shallow root system. Thus, landscaping around it can harm the roots and rob them of oxygen. It provides dense shade, so not much grass grows around it. If limbs have been cut to reduce the canopy, grass competes with it for nutrients and water during a drought. So don’t try to grow plants around it, and mulch it versus letting grass grow up to the trunk.

Heat stress is a major problem of this tree. That’s why you don’t see it growing in the southern states. When it’s stressed, it’s susceptible to disease. But heat stress would have different symptoms than we saw on Dale’s tree.

To get a better idea of what was happening, he brought in a 1-inch caliper branch. It had just a few leaves, which were much smaller than usual and had several fruits (helicopters). The tree is trying to reproduce because of the stress it is under. These are typical signs of verticillium wilt, a soil-borne disease. It will persist in the soil almost indefinitely.

The disease can kill a tree quickly due to its ability to spread through the plant’s internal system. It invades the xylem where water flows up and down the tree, just below the bark. Other signs of this disease are wilted leaves on just one side of the tree and discolored areas under the bark. These areas will have green to black streaks. Many times, the outer margins of the leaves will turn brown first in July or August. Some trees can get this disease and survive for years. Others go quickly.

There is no cure, just management. Fungicides do not work. A few trees can recover with time, so don’t remove the tree immediately. Contact a certified arborist for an analysis of the tree’s health.

To learn more about verticillium wilt and for a list of replant trees that are resistant or immune to the disease, go to http://go.osu.edu/vwilt.

To learn more about Norway maples, go to go.osu.edu/norwaymaple.

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hot line at 330-533-5538 to submit your questions. Regular clinic hours are Mondays and Wednesdays from 9 a.m.-noon.