Fast-Growing Trees may Have Faults

One of the conditions a home owner often specifies when selecting a tree is, “I want something that grows fast.” Fast growth, however, may sacrifice other qualities. A look at some of the fastest growing trees may uncover some structural problems, or indications of future problems. If we are willing to accept the faults, or take care of the problems, we can use fastgrowing trees as a source of quick shade. If we do, it may be better to consider them a temporary planting. We should plant more durable, slower growing trees at the same time, so the fastgrowing trees can be cut out as the permanent trees reach a functional size.

One of the fastest growing large shade trees is the silver, or soft, maple. The leaves have a silvery-gray underside, which is attractive as the wind blows. The wood is quite soft, and when limbs become fairly large, they break easily during strong winds or ice storms. It becomes an extremely large tree, so it may become dangerous if planted close to buildings. Because the tree grows rapidly, it has a high water requirement and is notorious for plugging sewer lines. It has large shallow roots that lift sidewalks and make growing grass beneath it very difficult. Limbs also grow with narrow angles that make them even weaker. Nevertheless it is an attractive, large, fast growing tree for a few locations where these faults do not create problems.

Another fast-growing tree is the Siberian elm, also often called incorrectly a Chinese elm. It becomes a smaller tree than the silver maple, and therefore may be better used in more limited space. It also grows extremely rapidly, and its wood is weak and easily broken by storms. Another serious fault of this tree is the damage done by an insect known as the elm leaf beetle, which skeletonizes the leaves, turning them brown in mid-summer. The black larvae and the adult beetles cause damage. The pest often must be controlled by sprays or entire trees may be defoliated.

Green ash is a fast-growing tree, especially when young. It eventually develops into a broadheaded tree with a round crown. Ash trees exist as both male and female trees. In the landscape, male trees are most desirable, because they do not produce seeds and are less messy. Female flowers are also subject to an insect that causes galls on them. Borers may sometimes attack a tree, but when the tree is vigorous and fast growing, it is able to recover from borer damage. Ash trees are one of the more desirable of the fastgrowing group.

Sycamore, or plane tree, is a native tree that is also fast growing. For many home landscapes, however, the tree becomes too large. In the lawn it is considered a rather dirty tree, because it is constantly dropping bark, leaves or seed balls. It is also susceptible to a disease that may kill twigs or disfigure leaves during wet springs. The London plane tree and the Oriental plane trees are more resistant to this disease than the American species, and do not grow quite as large.

Red maple and Bradford pear are two other fastgrowing smaller trees. Both have few problems, but like so many fast-growing trees, their wood is somewhat weak.

Slower growing trees can become fairly fastgrowing trees if given excellent care during the summer. Keep the trees well watered but not overwatered. Fill around the roots with good soil when planting. Do not fertilize at planting, but once a tree is established, fertilize it yearly in fall. Keep pests under control. Wrap trunks to prevent sunscald. With regular care, even a fairly slow-growing tree can produce shade more quickly than might have been expected.

• © 1988, International Society of Arboriculture. All rights reserved.