Fast-growing Trees to Avoidcomments (48) July 17th, 2012 in blogs
Many trees take decades to reach full size, and in this fast-paced world, not everyone has the patience to wait that long. Fortunately for the eager gardener, there are species that mature relatively quickly, and in the September/October 2012 issue of Fine Gardening (#147), North Carolina Master Gardener Linda Brandon shares 11 of her favorite fast-growing trees for impatient gardeners.
Some trees that grow quickly should be avoided, however, because of weak wood, numerous pests and diseases, invasive roots, a short life span, or other undesirable qualities. Here is her "dirty dozen":
Leyland Cypress (x Cupressocyparis leylandii)
Zone 6 to 10
This tree has so many negative characteristics, its success is truly a testament to the nursery industry's marketing efforts. Granted, it grows very rapidly, eventually reaching a height of 70 feet or so. However, with a life expectancy of only 25-35 years, it essentially starts to decline just as it's reaching its full height, and it is susceptible to a host of insect and disease problems. Bagworms are a major issue, requiring either hand-picking or spraying with an insecticide-and either hand-picking or spraying a 50-foot tall tree is a major (and expensive!) undertaking.
Diseases affecting Leyland cypress includ seiridium canker, botryosphaeria canker, cercospora needle blight, and a variety of root diseases. And think about it: Does your home landscape really need a hedge the height of a five-story office building? Compounding the problem is the fact that people often plant large numbers of these trees as monoculture screens, which means that whatever affects one plant will likely affect all of them. To add insult to injury, some salespeople cheerfully suggest planting these trees twice as close together as they should be planted, saying, "You can always take out every other tree when they get crowded," and you have a recipe for disaster. This is the source of the largest number of tree problem calls to our Extension Master Gardener Volunteer office Information Line.
Bradford Pear (Pyrus calleryana 'Bradford')
Zone 5 to 9
Bradford bear is the source of the second largest number of problem calls. This is a lovely tree: the spring bloom display is breathtaking, the overall shape is exceptionally symmetrical, and the fall color is glorious. It grows rapidly to 30-50 feet, with a spread of 20-35 feet, and it tolerates a range of soil conditions. Unfortunately, its branching structure leads to large branches or whole sections of the tree simply splitting away from the trunk during winds or ice/snow events. At that point, its highly symmetrical profile is no longer even remotely symmetrical; since they're often planted in matched sets lining a driveway, the beauty of the entire planting is irrevocably damaged. They are also, unfortunately, an invasive plant in many areas of the country. To top things off, Bradford pears have a fifteen-year life expectancy-essentially making them "disposable" trees. Avoid at all costs.
Walnut (Juglans nigra)
Zone 4 to 9
Black walnut is a beautiful tree, reaching a height of 75-100 feet, with a spread to match. It tolerates drought and rabbits, provides edible fruit, and makes a lovely shade tree. Unfortunately, its roots produce chemicals called juglones, which are highly toxic to a wide range of desirable landscape plants (azaleas, rhododendrons, blueberries, peonies. tomatoes, peppers, and potatoes). Additionally, the husks of the nuts can stain clothing and sidewalks, so unless you have a really large landscape that will allow you to give this tree its own space, you'd do well to stay away from black walnut.
White Mulberry and Red Mulberry (Morus alba, Morus rubra)
Zone 4 to 8
Growing to 35-50 feet, with a spread of 35-40 feet, these are attractive, easily grown trees with interesting foliage and edible fruit. Their fruit is very attractive to birds, they tolerate a variety of growing conditions, and they naturalize well (and are, in fact, native to much of the country). However, both of these trees have weak wood and very weedy seedlings; white mulberry is invasive through much of the country, while the fruit of the red mulberry is very messy and will stain clothing and patios. Borers, whiteflies, bacterial blight, coral spot canker, bacterial leaf scorch, powdery mildew, root rot, and witches broom are a few of the other problems that can affect the trees, along with scale, mites, and mealy bugs. All in all, best to give this one a wide berth.
Sycamore (Platanus occidentalis)
Zone 4 to 9
Sycamore can be a magnificent specimen, growing 75-100 feet tall and wide, with a trunk diameter easily reaching 8 feet, characterized by mottled, exfoliating bark. Sadly, it is prey to sycamore anthracnose, a significant disease that can severely damage the tree. Canker, leaf spot, powdery mildew, borers, scale, Japanese beetles, caterpillars, and mites all afflict sycamores. More important to homeowners, though, is the fact that litter from the leaves, twigs, bark, and fruiting balls pose significant problems in terms of maintaining a neat landscape. With so many marvelous trees available that don't have these problems, why invest in this one?
White Pine (Pinus strobus)
Zone 3 to 8
White pine is a moderate-sized tree, reaching a height of 30 to 40 feet and a spread of 7-10 feet. Unfortunately, it is affected by white pine decline, which causes needle discoloration and browning, shriveled bark, oozing sap, and, in some cases, death. It's also vulnerable to injury from salt spray, ice damage, and winter burn, and it's susceptible to ozone damage, an increasing threat in urban/suburban areas. White pine is also much loved by bagworms and yellow-bellied sapsuckers. Again, why plant a tree that you know is prone to this many problems?
Birch (Betula spp.)
Zone 4 to 9
Several varieties of birch are lovely landscape plants; a few sport dramatic exfoliating bark. In addition, many thrive in wet environments; avoid planting in a hot, dry location, and aim for afternoon shade. Generally reaching 40-50 feet, occasionally available as a clumping tree with 3-5 stems, birches, particularly river birch (Betula nigra), are popular landscape plants. Many birch varieties are susceptible, though, to the bronze birch borer, a tree killer, and they have a very shallow root system that can be easily damaged by soil disturbance. Birch leaf miner is another significant problem, and control requires spraying, which is time-consuming and costly. Not a tree to be avoided at all costs, but think carefully before planting.
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