Ask Mr. Answer Person: "What is going on with maple trees in Decorah?"

Photo by C. E. Price [Public domain], via Wikimedia Commons

Susan e-mails: "Dear Mr. Answer Man:  You always seem to know the answer to most questions - or know where to find the answer.   What is going on with the maple trees in Decorah? So many have dead branches in them. Someone working for a tree service told my neighbor it is due to "girdling." I find this hard to believe. It is happening to trees all over town - all at the same time.   In my neighborhood there are three maple trees - one has already been taken down - that have or had dead branches in them."
 
Mr. Answer Person says: "City forester Drew Stevenson has given us an answer to your questions.  He points that "girdling" is used to describe tree roots in this case--not the tree trunk.  Says Drew, "Maple trees have a tendency towards developing girdling roots.  This is due to advantageous root growth from trees that were planted too deep or buttress roots that were damaged, usually during digging from a nursery.  As these new roots grow, they tend to follow the path of least resistance following the hard pack that was caused by digging the hole the tree is being planted in.  As the tree and root grow they come into contact with each other, and the root structure being much stronger than stem tissue, the vascular system of the tree is crushed.  This kind of root growth happens to all trees but is especially prevalent within the Acer species."

He continues, "The majority of trees planted throughout most urban areas are planted at a improper depth.  Stem tissue is not well adapted to surviving under ground, and will decay if it is buried.  This is a problem that can be easily remedied during planting, but unfortunately this issue causes premature decline and death for the tree.  Weather does have an affect on tree health and will compound the severity of the above issues.  Draught, especially in the spring, will amplify the affect that improper planting depth and girdling roots have on a tree, causing terminal twigs to decline and early leaf color change."

Concludes Drew, "Due to improper tree care practices, starting at planting and continuing through out the life of urban trees, unfortunately the average life expectancy for urban trees is drastically diminished.  Most of these maple trees were probably planted when the elm population was removed and are most likely the same age, which would explain why trees through out the city are declining at a similar rate."