Daniel Gill, Bogren, Richard C. | 7/28/2008 8:24:50 PM
By Dan Gill
LSU AgCenter Horticulturist
You must be careful with several things you may do in your yard or garden to avoid damaging your plants. Here are a few things to be aware of.
Avoid mower and string-trimmer damage
String trimmers that use a monofilament line for cutting down weeds and grass can be very damaging to young trees, which have relatively thin bark. If the line is allowed to hit the trunk, part of the bark will be removed with each swipe of the line. If you’re not careful, you might even remove an entire ring of bark all the way around the trunk, girdling the tree. Mowers pushed hard or dragged around the base of a young tree can be almost as damaging.
Just under the bark lies the part of a tree’s circulatory system that carries food manufactured by the leaves to the roots (which can make no food for themselves). Damage that occurs when mowers or string trimmers remove patches of bark interferes with the tree’s ability to send food to its roots. As the roots are deprived of food, they become stunted and function poorly. This leads to a stunted, unhealthy tree. Remove a complete ring of bark, and you may cut off food to the roots altogether, leading to the plant’s death.
In addition to interfering with food movement, open wounds created by mowers and trimmers can provide entry points for disease organisms that can cause decay. Many sickly, stunted trees that have been planted for years but don’t grow well have been damaged in this way. Look at the base of their trunks and you will often see scars and callus growth from repeated injury to the base of the tree.
To prevent these problems, don’t allow grass to grow close to the base of young trees for the first three to five years after planting. Keep an area at least a foot out from the trunk grass-free. A mulch 2 or 3 inches thick spread evenly over the area – but pulled back slightly from the trunk – will help a lot. Any stray weeds can be pulled or killed with a quick spray of herbicide if necessary.
Shrubs are generally planted in beds, so they’re less at risk. But I have seen this problem occasionally when ground covers, such as Asiatic jasmine, are trimmed away from the base of shrubs with string trimmers. Whether you maintain your landscape yourself or pay someone to do it for you, don’t let this kind of needless damage happen to your trees and shrubs.
Don’t damage roots
Trees also are vulnerable to root damage from construction and filling. If you plan on doing construction – whether building a new home, adding on to an existing one or even putting in a patio or repairing driveways or sidewalks – tree roots will likely be an issue.
Tree roots extend well beyond the reach of the branches, and the majority of the feeder roots (those that absorb the water and minerals from the soil) are located in the upper 8 to 12 inches of the soil. This makes them much more vulnerable to damage than most people appreciate. If you will be doing construction or filling around valuable existing trees, consider consulting with a licensed arborist before the work is done to make sure the trees are damaged as little as possible.
Be careful with pesticides and fertilizers
Another way gardeners damage landscape plants is by improperly using pesticides and fertilizers. These products are useful and sometimes necessary to maintain a healthy attractive landscape. But if they’re misused, they can do more harm than good.
Pesticides commonly used in the landscape include insecticides (to control bugs), fungicides (to control diseases caused by fungus organisms) and herbicides (to control weeds). Landscape plants can be damaged by all three, but most damage occurs from insecticides because we use them more often than other types, and herbicides, because they are designed to kill plants.
You can avoid damaging plants with pesticides by carefully reading and following label directions. I know the print can be very fine, but do like I do and get out the magnifying glass if you need to. Without complete information on how to use a product, your efforts may be wasted because applying the pesticide incorrectly does not control the pest and even may injure the plants you were trying to help.
Insecticides will list on their label which plants may be damaged by them and any temperature limitations. (Some insecticides will damage plants if applied during hot weather.) And many insecticides will burn or damage plants if you mix them too strong. You can see how important it is to know of these potential problems. Avoid them by following label directions.
Since herbicides are designed to kill plants, we must be particularly careful when using them around desirable ornamentals. Again, read the label to make sure the herbicide will do the job you need it to and to understand how to use it properly.
Many people also damage plants with fertilizers or plant food. Gardeners often think if a little is good, more is even better. Fertilizers should never be applied stronger than label recommendations. You may apply less than is recommended, but mixing fertilizer stronger or applying more than is recommended on the label can lead to serious damage to your plants.
Contact: Dan Gill at (225) 578-2222 or firstname.lastname@example.org
Editor: Rick Bogren at (225) 578-2263 or email@example.com