Writing a garden column usually means writing about plants, not people. But occasionally I find someone so connected with certain plants that I simply must share his ideas and experience.
Alex Shigo, a researcher from Durham, N.H., has spent his entire professional career studying trees. He dissected more than 15,000 trees in his work with the U.S. Forest Service. He recently visited Salt Lake City, and I spent several days with him in a workshop learning about trees.While Shigo is one of the world's great authorities on trees, learning in his workshops is not all stuffy academics. His desire is to teach tree care by using all the senses, including touch. His presentations, while scholarly, are flavored by his great love for trees and reverence for the process in which trees grow and develop. His practical agrarian approach, tempered with New England humor, made learning a delight. He shared excellent information I would like to share with you.
Trees are dynamic organisms that can grow and develop for many years. However, those planted in cities often live for only seven to 10 years. What makes the difference?
One important reason is pruning. Poorly planted and pruned trees often develop fatal problems. Each spring gardeners get the urge to prune. Pruning disasters result because of ignorance about how trees grow and defend themselves. We want instantaneous results on everything and want tree pruning reduced to one or two simple rules. I am opposed to such rules, but will state one to help prevent some of the senseless butchering that is done to trees and called pruning.
The basic rule of tree pruning is that trees are organisms of great dignity and deserve our respect. If that rule were followed, it would eliminate many of the horrendous practices currently afflicted on trees.
Topping is a serious problem for trees worldwide. Topping not only destroys the dignity of the tree, but it also weakens the tree and changes it from a strong, healthy specimen to a hazardous tree. Topping is done under the pretense that it makes the trees grow well. Most people erroneously believe that topping will make their trees safer and reduce the height. Unfortunately, neither is true. Topping not only make the trees more hazardous, the new sprouts often grow taller than the original sprouts. These sprouts grow from dormant buds in the tree bark, often from near the same position, and squeeze together at the base, killing and forcing off branches. This weakens the branch attachment even further. Sprouts are particularly dangerous as they grow large but are only weakly attached to the top of the tree.
Another serious problem with topping is the removal of the living, energy-producing parts of the tree. This weakens the tree and opens it up for decay organisms to invade. These do further damage to the tree. They also make the tree even more dangerous as the wood in the top of the tree rots away.
Fortunately, the prohibition against topping does not mean that trees cannot be pruned. Large shade trees may need pruning, but safety is always the first consideration. Never attempt to prune large trees unless you are properly equipped to do so. When choosing an arborist, don't be afraid to ask for references and to view trees they have pruned. A good pruning job on a large shade tree is very much like a good haircut. Butchered, topped trees do not mean the trees are pruned properly. Well-pruned trees still maintain their dignity and natural shape after pruning.
The most important pruning on large shade trees is to correct obvious hazards or defects. These hazards or defects include crossing branches and broken, dead or diseased branches. Suckers (vigorous sprouts growing from the base of tree) or water sprouts (vigorous upright branches) should also be removed.
Shade trees do not need the severe annual pruning that fruit trees need to force production of fruiting wood. The pruning and training the trees receive during the first five years often determines how well they will grow for the rest of their lives.
Each tree has a natural shape that should be preserved. Never attempt to make a weeping tree into an upright tree or vice versa. Such pruning shows no respect for the dignity of the tree and the results are disappointing. Topping is extremely injurious to the tree. Don't be guilty of it yourself, and certainly, never hire anyone who insists on topping trees. Those who insist on such practices do not understand trees or tree care.
Next week we will have more on how to prune and protect your large shade trees.