Gardening: Thinning trees is better than topping

Pealing bark is natural for a river birch tree.
Pealing bark is natural for a river birch tree.

Q. We have a hard maple tree in the front yard. The tree looks healthy except the green leaves on the new growth are falling off. Late last fall, we had it shaped up taking about 4 feet off all around. This is the first year we have had this problem. The tree is about 30 years old.

— G. P.

A. Whenever a tree is pruned by removing a large amount of leaves, it sets up an imbalance between roots and stems. In the following year, there are latent leaf buds which ordinarily do not open and set forth leaves. But with extra nutrients and water available, these buds break out and grow very quickly. With any type of spring winds at all, the slender branches break off and tender leaves are torn off.

Your photos show a large number of fast-growing branches that need to be thinned out to allow more wind to pass through the canopy of the tree. Most of these newly developed branches are growing straight up and will become very weak over time. The larger they grow, the more damage they will do to the structure and support of the tree.

This is the danger of topping trees compared to thinning out selective branches and/or thinning branches back. Mother Nature will do this but will not select the best and healthy branches to remain. A qualified arborist knows how to thin trees, but you will have to paya little more for his knowledge rather than just having someone cut all branches down to a certain level. This person will remove whole limbs when he notices disease or insect damage or finds there are many competing limbs trying to use the same space.

All your newer branches about 1/2 of an inch in diameter or smaller will continue to lose leaves throughout this growing season and some of these smaller branches will break off.

Q. I am sending pictured of a birch tree. I would like to know what is wrong with it. The bark seems to be peeling off badly all up and down the tree. This tree is a river birch. There are pieces of the bark in the yard all around it. Could it be a lightning strike? There does not appear to be any damage in the tree or at the base. Any help would be appreciated.

— L. H. of Worden

A. A river birch (Betula nigra) naturally has light reddish-brown to cinnamon-colored peeling bark. This peeling takes place almost every year. As this birch ages. the bark will also become deeply furrowed and form irregular plate-like scales. This is an ordinary growing condition of river birch.

Since there is no damage to the trunk or the base of the tree, there is no lightning strike damage. Sometimes with wet weather in the spring, the river birch can grow faster than ordinary and the bark may peel a little more. This tree usually grows by the banks of streams, so it can withstand flooded conditions. This is also one tree that should be pruned in the middle of summer because sap runoff can be a problem in the spring for these big “bleeders.” This sap can attract insects, diseases and even woodpeckers.

Charles Giedeman is a local contributing writer. Send your gardening questions to Lifestyle Editor Patrick Kuhl, Belleville News-Democrat, P.O. Box 427, 120 S. Illinois St., Belleville, IL 62222-0427, or email them to

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