Thursday, July 1, 2010

I would sure hate to lose that tree!

If I have heard this declaration once, I have heard it a hundred times. Often, it is prefaced by the words, “I have this 250 year old oak and...” Of course, there is not always anything we can do to save a tree that has lived out its lifespan and is being called back to the soil by Mother Nature.

Most trees die gradually over a long period of time. Remember that trees must continue to grow every year of their lives. As they get older, the growth rate slows way down but they must still expand in girth. We can see this because they produce an annual ring in their wood for each year of their life.

As trees reach their mature size in our landscapes, their root zones often become limited by buildings, sidewalks, streets, driveways and other trees. If they cannot compete for the needed water, nutrients and sunlight, they begin to decline. Soils become compacted and do not allow water and oxygen to penetrate to the roots.

At first, the tree will produce fewer and smaller leaves and small branches begin to die. Then, insects such as borers can sense the tree is in trouble and they attack, further weakening it. Diseases such as leaf spots which are normally no more harmful than the common cold is to people, become more serious.

In the final stages of this downward spiral, the tree may begin to rot while it is still alive. Shelf mushrooms may emerge through the bark near the base of the main trunk. Mushrooms may begin popping through the soil in the root zone of the tree. Wet, weeping cracks may appear in the bark of the tree. These are all signs that the tree is beginning to rot.

Once these symptoms appear, it is for sure that the tree is losing some of its structural strength. It is more likely to fall over in a wind or ice storm than a tree that is not rotting. The difficulty is that you cannot predict when this will happen. The tree may stand for several decades or it may topple on a nice, calm day in June. All that can be said for certain is that it is not as strong as it would be without the rot.