It’s a beautiful spring day. The maple that you planted ten years ago is beginning to leaf out nicely. The eucalyptus that your family planted for a wind screen now blocks the wind at 90 feet. You look your trees and wonder how they got so tall so fast! And you think to yourself, boy are they getting tall. What should I do? Should I cut them in half? Should I remove them? But I like the trees! How will I be able to pay for them?
If you asked an arborist these questions, you may be surprised at the answers. He or she may first respond by explaining that it is never appropriate to top your trees. Much literature is available on the topic of tree topping. See the ISA’s article on tree topping. But this doesn’t fly with many homeowners. Tall equates to hazardous for most people. But is this really the case?
Fast growing trees are not a problem in themselves. Increases in height of trees does not necessarily equate to increasing hazard. Trees respond to vertical growth by increasing the surface area of their root system. Redwoods are a great example of this. Redwoods often grow to massive heights rather quickly (in 50 years they can obtain heights of 150ft+). Yet redwoods are some of the sturdiest trees to the elements, and complete failures of redwoods are rarely seen, especially when compared to other fast growing trees. Their shallow root systems expand to cover large areas, often grafting with other redwoods and other tree species. Basically, the trees respond to their height horizontally to stabilize themselves.
The problem with fast growing trees usually lies in the type of tree and the corresponding lack of maintenance. First, identify what type of trees you have. The Internet is a great resource if you have some information already about the tree. The National Audubon Society’s “Field Guide to trees, Western Region” is an excellent identification guide.
Fast growing species occur locally as native trees, weeds, and as landscape/planted specimens. Fast growers found locally: natives= alder, big leaf maple, box elder, cottonwood, ceanothus tree, Douglas fir, madrone, Monterey pine, sycamore, redwood, and willow species; invasive weeds= ailanthus, blue gum eucalyptus, ceanothus (in some areas), acacia dealbata (yellow flowers) and black acacia (both are common weeds seen all over Santa Cruz county), locust; some of the many planted/landscape trees = black walnut, birch, catalpa, elms (American and others), Eugenia, Hawthorne, Italian cypress, fruitless mulberry,ironwood, liquid ambar, Modesto ash, myoporum laetum, poplar, silver maple, and weeping willow.
Of the above trees, none of the invasives should ever be planted. Santa Cruz County is already plagued by these trees. If a homeowner is worried about the height of any of these invasive trees, in most cases an arborist would recommend full removal. The invasive trees are all prone to routine failures and removal is almost always the only option. Fortunately these invasive trees do not grow very tall, with the exception of blue gum eucalyptus, which under optimal conditions can grow 12-15ft a year to a mature height of over 200ft. Eucalyptus are known to drop entire branches as they grow. Eucalyptus forests are littered with dead branches, some very large. It is said that campers in Australia never set up camp underneath Eucalyptus branches. The same could be said about planting your house under eucalyptus branches….
The native trees in the area should not be topped either, as they reach substantial heights with the exception of ceanothus and willow. Moreover, these trees are quite safe at mature heights when maintained properly. Have an arborist inspect your mature trees for any signs of disease, decay, or structural deformity. Madrones have a short lifespan (up to 85 years), so watch these trees carefully. Douglas fir when topped forms severe bark inclusions, and can be very dangerous when the new tops grow to large sizes.
Landscape trees are most often topped for aesthetic purposes, not for safety. The fast spindly growth of these trees are often not preferred. If they were topped for safety, the procedure of topping would make them more hazardous.
There are certain species of fast-growing landscape trees in Santa Cruz County that need to be topped for maintainence (small yards/growing area, overhead voltage concerns). Mulberry is one of these species. Ironwood is an example of a tree that grows faster than its structure can handle. They are know for dropping large limbs. When this tree reaches mature height, removal is the preferred practice. Birch is a very brittle tree, and the tops often sag making their appearance aesthetically unpleasing. These trees are routinely topped, and birch is one of the better trees to top if topping is selected. It is one of the rare exceptions to the topping rule. Fruit trees are also topped to control the amount of fruit and to make harvesting easier.
Topping has its consequences, however. Some trees never regrow from topping. Many trees respond to topping by shooting water sprouts that exceed the natural growth rate of the trees. After hard dormant (winter) pruning of fruit trees, long water sprouts appear in the spring with heavy fruit that makes branches break under their own weight. Furthermore, topping leads to weak attachments for the new growth at the point of the cut, leading to bark inclusion and failure of these new tops. It increases the potential for rot, and stresses the trees natural defenses to ward off disease vectors and fungal rots. It can be very expensive also, as the following paragraph explains.
Fast growers are often not pruned correctly, and when they are, not followed with a maintenance schedule. When trees are not pruned correctly potentially hazardous branches are not removed or are formed by improper cuts. Tree services that top trees often use climbing spikes to perform the work, leading to more problems for the tree. The customer is left with trees that are prone to an increased stress by the external environment. To make matters worse, trees are often overlooked by busy schedules and tight finances. The rate in which fast growers grow demands continual attention by homeowners. Trimming these trees only once is almost always not feasible. Eucalyptus near houses, for example, should be maintained yearly, or at least every 3 to 5 years. When a tree such as a eucalyptus is neglected and becomes hazardous, the customer could be looking at thousands of dollars for removal.
If your fast-grower has already been topped, what should you do?
1) If the tree has been growing quickly above the topped cut, it is quite likely that a hazard is present. Have an arborist evaluate the tree/trees. This may include the arborist climbing the tree to look for cavities, defects, inclusions, etc.
2) Consider having the tree removed altogether and replaced with a tree that is easier and less costly to maintain.
3) If budget is a concern, consider having the tree topped again and then removed when more funds are available. Sometimes moving trailers, cars, or even structures is more economical than tree removal.
4) Don’t ignore it unless it is a tree in the forest that if it falls and no one heard it, did it really fall?
Craig Erickson
Certified Arborist WE 6869A
Owner- Koala Tree Care