Q. I have a few questions about a large silver maple in my front yard that I was hoping you could answer. A former owner had it topped 8-10 years ago. Many of the smaller branches are dead. I have had three different companies come to look at the tree, make recommendations and give me an estimate on trimming it back and removing the dead branches.
All three companies agree that a silver maple should be pruned rather than topped and two of the companies have said that even though it shouldn’t have been topped, now that it has, I have no choice but to continue topping it. The third company disagreed and said that it certainly could be pruned and that it should be pruned rather than topped again. They mentioned crown restoration and fertilizing the tree. I am not sure who is correct and whether the tree really needs to be fertilized. Do you have any suggestions?
A. Topping is the practice of radically cutting back large branches on mature trees to short stubs. In trees that grow with a single main trunk, it is literally cutting the top off the tree. Topping is generally employed when a tree has outgrown its space and is interfering with utility lines, hanging over rooftops, or making the neighbors complain.
Topping is a poor substitute for proper plant selection (I realize that many people inherit problem trees when they purchase property). There are many lovely trees that provide shade and shelter without getting so big that they pose a threat to property and utility lines. While many homeowners think that they are protecting their property by having large trees topped, it actually increases the likelihood that the tree will become a hazard in the future. Topping injures a tree in a number of ways, making it more susceptible to infestation by insects and disease-causing organisms.
Topping removes a large area of leaf surface very suddenly, thus limiting the amount of food reserves it can produce through photosynthesis. There is a balance between the crown (top growth) and root system of a healthy tree. Topping removes so much of the tree’s crown that this balance is thrown out of whack, and the tree is unable to provide sufficient nutrients to its root system.
Also, topping is a shock, because a tree’s crown protects much of the tree from direct sun. Just as a person who has not been out in the sun can be severely sunburned when they go out on a sunny day, so can the interior portions of a tree when that protection is removed suddenly. In trees this is called sunscald, and it injures and kills portions of the bark. These areas are prime targets for infestation by insects and disease-causing organisms, as are the big wounds left behind when large branches are removed.
Although people have trees topped to reduce their overall size, trees respond to such drastic pruning with rapid re-growth. Often known as watersprouts, the vertical, rampant growth that results from topping elongates much quicker than normal growth. The tree returns to its original height in a short time, defeating the purpose of topping the tree in the first place. These watersprouts are also much more numerous than normal growth, resulting in a crown that is much more dense. They tend to be attached more weakly than true limbs, so a topped tree winds up with a far more dense and dangerous crown. The numerous sprouts tend to catch the wind rather than allowing it to pass through the crown of the tree, making it more likely that these large sprouts will come down on a windy day.
Finally, a tree that has been topped is an ugly tree. Topping makes a mockery of the loveliest tree, and it will never regain its true character afterwards. Topped trees actually reduce the value of a property, while mature trees that maintain their true form add value to a property. It may seem cheaper initially, since it takes less skill and time than proper pruning, and generally does not cost as much. However, topping costs more in the long run. If the tree dies as a result, there is the cost of removal and replacement. There is also an increased liability from the dense crown, weakened branches and damage from insects and disease.
I have to agree with the third company that gave you an estimate. Although the tree should not have been topped, it is possible to thin out the water sprouts, leaving the strongest and best placed and removing the rest in order to restore the crown to some semblance of health. Continuing to top this tree just adds insult to injury.
Fertilization should be based on the results of a soil test. Mature trees have less need for fertilizer than other plants. If you have not done so already, the tree would be best served by removing the grass under it and replacing it with coarsely shredded hardwood mulch.
Grass is a ferocious competitor for water and nutrients, so getting rid of it reduces potential drought stress for the tree. Also, the mulch contributes organic matter and nutrients to the soil as it breaks down. Ideally the mulch should be two inches deep and extend from near (but not touching) the trunk out to the drip line (the ends of the branches).