Released July 3, 2008

LAWRENCE, Kan. – Trees are amazingly resilient and can outlive humans. But, landscape trees tend to need help, said Jennifer Smith, Kansas State University Research and Extension horticulturist.

“In most cases, you’re too late once decline becomes evident in a mature tree,” Smith said.

Trees signal when they’re going downhill. They produce heavy seed crops and exhibit some branch dieback. Their leaves change color earlier in fall. With some trees, their leaves become smaller than average and may decline in number, too, making their canopy look sparse, the horticulturist said.

“These symptoms don’t appear in any particular order, and they usually develop over a period of years. They can be easy to overlook for quite a while if you’re taking your trees for granted,” she said.

Established trees almost always decline and die as a result of a combination of factors. All of the factors cause plant stress. Some, such as harsh weather, are not preventable. Yet, all are observable, Smith said, and the following can help trees avoid or survive stress better:

• Ensure your trees get enough moisture to make and store food, rather than draw on and perhaps deplete their food reserves. Irrigate slowly and deeply during extended dry weather – summer or winter.

• Mulch to reduce moisture fluctuations, but leave inches of mulch-free zone around the trunk.

• Do not pile additional soil over a tree’s root system – which can extend beyond its drip line.

• Avoid cutting into roots for any reason, and be careful with lawn equipment. String trimmer and lawn mower damage injures a tree’s vascular system. The wounds don’t heal completely and can kill.

• If you have a young tree that was planted too deeply, pull soil and mulch away from its base. A tree is at the proper depth if you can see the top of a horizontal root(s) emerging at the base of the trunk. Combined with any needed pruning, done correctly, these steps also will make trees less vulnerable to insects and diseases, Smith said, because “it’s always easier to keep a healthy tree healthy.”

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http://isis.oznet.ksu.edu/KSRENews/story/briefs070308.aspx

Contact: Mary Lou Peter-Blecha, mlpeter@ksu.edu