There are a lot of myths and fallacies regarding tree care that have developed over time. Many of these are the remnants of out-dated practices that can actually do more harm to your tree than good. Here are a few common misconceptions about trees:
Myth #1: Tree root systems resemble a mirror image of their canopy.
When people see the beautiful, towering canopy of a bur oak tree or the plentiful understory layers of a pagoda dogwood shrub, they often envision them having a root system underground that looks similar in both height and spread.The growth of tree roots is commonly misunderstood, and while a few roots may extend several feet deep, it is actually rare for many to exist at such significant depths. Trees and shrubs often have a larger supporting root system closer to the the base of the trunk which then tapers off quite rapidly into a series of very fine feeder roots, with the vast majority of them located in the top 50cm of soil. This shallow system of roots often extend up to 2-3 times the width of the overhead canopy - which is very different from what you see above ground.
Myth #2: Topping large trees is a cost-effective way to prune and can reduce overall growth.
Homeowners sometimes top their trees in order to reduce the overall size and growth; however, pruning a tree this way can actually create the opposite effect. When a tree is topped, numerous weak and elongated shoots grow in the place of what was removed and the tree quickly returns to its original height with a much denser crown. Proper pruning practices dictate removing no more than 20% of a tree’s crown (leaves) at one time. Removing more than 20% can severely limit the tree’s ability to photosynthesize and produce the sugars it needs to sustain itself. Not to mention, the burden of long term costs. Topping may seem like a cost effective method in the short run, however, the fast-growing, weak branches that sprout after topping can present greater risk and cost more to maintain in the long run.
Tree that was staked for too long and with improper materials.
Myth #3: All young trees must be securely staked after planting.
If you are planting a tree that has a good root to canopy ratio (in other words the tree is fairly small on top and has a fairly large root ball), staking is not likely necessary. In fact there are benefits to NOT staking. Newly planted trees put most of their energy into growing a well-established root system. This root growth is actually stimulated by the gentle movement of the tree in the breeze. Trees that are staked tightly cannot move and those signals are not transmitted.
If your tree has a lot of top growth already and not a very large root ball (meaning it may be at risk of falling over before it can anchor itself by growing a good root system), or if you are in a windy or high foot traffic area, staking may be necessary. Using soft, flexible staking materials is very important. The days of metal posts and wire ties are over (or should be!) Always remember to loosen or remove all staking materials after one year. Never leave them in place for more than two years or you risk girdling your tree.
Myth #4: Wound dressings or wound paint will help heal tree wounds, prevent insects/disease from entering the tree and reduce decay.
Trees recover best from pruning or other wounds by using their natural defense mechanisms to carry out a process called compartmentalization. During this process,the tree grows special cells that isolate the damaged area from the rest of the tree, reducing the risk of damage from disease, insects and decay. Wound dressings and wound paint were once thought to be a quick fix; however, research has shown that they actually cause more harm than good. Not only do they inhibit the natural compartmentalization process, they also seal in moisture which can lead to decay and sometimes provide a food source for pathogens.
Brenna Anstett is Field Operations Coordinator for LEAF.