Stop Tree Abuse!
Written for the Davis Enterprise, December 2001
Ok, that's it. I'm starting a new movement. Not underground: this is an aboveground movement to Save the Trees! Stop tree abuse! Our goals: eliminate improper staking, poor training, and inappropriate pruning of trees. Our mottoes: No topping! Ask before you prune! And a chain saw is not a pruning tool--except in the hands of professionals!
Years ago I lived on a street in Dixon that was lined with Modesto ash trees. One Christmas a neighbor got a chain saw, and that day his tree was amputated at the height he could reach from a step ladder. This "chain saw blight" quickly spread down the entire block (the disease is apparently linked to the human y-chromosome), and all of those trees are now disfigured and some have even died. Healthy, well-trained trees improve aesthetics, personal comfort, and property value. Abused trees are unattractive and can become an unsafe liability.
Goals of staking and pruning
Well-meaning humans are the number one pests of young trees! Staking and training of young landscape trees is done to develop a straight, well-tapered trunk, select branches that are well-positioned with respect to each other, and discourage very narrow or wide branch angles that might lead to breakage. (In public areas staking is also done to protect the trees from mowers and traffic). Set your young trees free! Stakes that are left on too long, or that are too tall at the time of installation, can rub against branches and cause wounds. Ties that are not loosened every few months can girdle and actually kill young trees.
How to stake young trees
A young tree usually needs to be staked for only the first 6 - 12 months. Always remove the nursery stake to which the young tree is tightly tied, and don't be surprised if the tree promptly bends over to the ground since the young trunk has very little caliper and no taper. The most common system uses two lodgepole stakes installed 12 - 18" from the trunk on the east and west sides of the tree (our prevailing winds are from the south and north, and you don't want the tree battering into the stakes in the wind). The tree is tied with two figure-8 ties made of soft material (such as rubber, plastic, or old nylons) at the point at which it bends, usually a little more than halfway up the trunk.
It is very important that the ties be tight enough to hold the tree upright, but loose enough to allow for movement of the trunk in the wind. Why? Because movement of the tree releases hormones that cause the formation of reaction wood, which is what thickens the trunk (arborists call this the taper of the trunk). This is why a tree growing alone in the open will be shorter and stouter than the same species growing in a grove.
How long to leave stakes on
Check the stakes and ties every few months, and remove them as soon as the tree can stand on its own. My inspiration for this article came when I was walking through the parking lot of the new Nugget Market Food Experience (it's not just a grocery store!) on Covell Blvd in north Davis. Healthy, vigorous sycamores reaching to 20' or more--with tree stakes hanging from them. Here's a hint: if the tree is more than twice the height of the stakes, they're long overdue for removal!
Wholesale growing techniques affect whether a tree needs staking. Growers often tie the young tree to a single stake, remove the lower branches, and then cut the top of the tree to induce branching. This produces a saleable product more quickly than if the trees were allowed to grow naturally, but it also means they have skinny trunks which can't support the tops. Coast redwoods and European birch trees rarely need to be staked because wholesale growers leave the lower branches on these species, which leads to a thicker trunk on the young tree. Trees that may need longer staking than normal include Crape myrtles, Chinese pistache, and Chinese tallow tree; these are slow to develop taper and may need to be staked for up to two years. Check the ties every couple of months to make sure they aren't too tight.
Training young trees
Nursery grown trees that have been topped have branches too close together, so training is needed. If all of those branches are left, growing thicker and heavier, disastrous splitting will occur (Bradford pears are notorious for this, and there are good examples of bad training all along F Street). Very narrow and very wide branch angles also lead to splitting. The young tree should have branches removed so that those that remain are at least 12" apart up the trunk, at angles of 30 - 45 degrees. (Note: Pruning of fruit trees has very different goals
that's a whole 'nother article!)
Pruning larger trees
Larger trees are only pruned to remove crossing or rubbing branches or that are at unsafe angles. Sometimes larger trees are pruned for size control, but this is usually because the wrong tree was chosen in the first place! Trees planted under power lines WILL be topped to keep them out of the wires. This, not the aesthetics of the resulting pruning, is the only goal of the tree services that work for utilities. Liability for fires caused by downed wires has made PG&E very vigilant about keeping the lines clear. Do them and yourself a favor and plant a small tree or large shrub instead.
When size control is needed a technique called "drop-crotching" can be used. This is where the central leader of the tree is cut down to the point where an existing lateral branch is already growing. That lateral will form a new leader and the basic shape of the tree is preserved.
Topping ("heading" or "pollarding") is rarely appropriate and is disastrous for the tree. Each cut results in a proliferation of vigorous shoots called "panic growth" as the tree responds to what it perceives as a natural disaster: as far as it's concerned it's been struck by lightning! All of these shoots are weakly attached and are likely to break or split in a few years, so a tree that has been topped once needs to be topped annually. This is often done to Fruitless mulberries and London plane trees. Why not just select a smaller tree in the first place?
With guidance from nursery and tree professionals, homeowners can do the staking and training of young trees, but work on larger trees should be done by Certified Arborists. These professionals have a minimum of three years of experience, have passed a rigorous exam in 12 areas of expertise, and must continue their education to maintain certification. Tree work is dangerous (climbing in trees with saws and dropping heavy branches from considerable height!) and requires knowledge and experience--far better to pay a professional to do it right than to injure yourself while doing it wrong!
© 2008 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616
Feel free to copy and distribute this article with attribution to this author.
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