Dieback is a process of decline which causes trees to give a portion of their leaves. It usually occurs as a result of some severe stress to the tree’s root system. There’s a delicate balance between a tree’s roots and the number of leaves it can support. If a tree loses part of its root system, it must also give up some of its leaves. However, this process doesn’t happen overnight.
Visible dieback of a tree takes time – often quite a long time from the date the roots system was injured. The larger the tree, the longer it takes for this stress sign to show up. With older trees, it could easily be a year or more before dieback is observed. Also the larger the tree is, the less disturbance it can tolerate to its root system.
A small tree will adapt to almost any growing condition that it has to. On the other hand, a mature tree is “set in its ways,” as the saying goes, and can’t respond favorable to changes in its environment. What can be done to prevent dieback in old trees?
Probably the first thing we need to realize is that trees, like all living things, have a natural life expectancy. Sometimes, no matter how careful you are not to disturb a tree’s environment, dieback will occur. Each year, trees grow new bark. But, this becomes more difficult as the tree get older. At some point, the tree won’t be able to grow enough replacement parts for those it’s losing. Once a tree begins this period of decline, there’s nothing you can do for it.
However, it is possible to extend a tree’s natural life expectancy and delay this inevitable period of decline. The most important thing you can do to extend a tree’s life is to protect its roots. Give a tree the space it needs. As I have said, a small tree can and will adapt to a limited space. A mature tree that’s forced to occupy a small space will not adapt.
Protect a tree’s bark as much as possible. Bark is a tree’s only protection. A wound that goes deep into a tree will expose the interior to all sorts of wood rotting fungi and boring insects. Treat all wounds with a wound dressing as soon as damage is noticed. When pruning, make clean cuts that are flush with the adjoining trunk or branch. Never leave jagged edges that won’t heal well.
Also be sure you keep your trees pruned away from utility lines. If you don’t do the pruning, the company probably will, and you may not be very happy with the results. However, always be cautious concerning the danger of electrical shock. If in doubt, hire a competent expert to remove limbs near power lines.
Be very careful when you use weed killers in your landscape. Some herbicides can hurt your trees, even if you apply them as much as 20 feet away from where a tree is growing. If you must use a herbicide anywhere near a tree’s trunk or root’s make sure the product is designed to kill green growth only.
One of the worst things you can do is start excessively fertilizing an old tree. You may think this will stimulate a tree and extend its life. For young trees, this may be true. But, for a mature tree, in its declining years, excessive fertilization will only cause problems. An old tree doesn’t need an overabundant crown. It doesn’t have the root system to support this excessive growth, and the tree will become top heavy.
For more information on Tree dieback contact the Gulf County Extension Service @ 639-3200, 229-2909 or visit our website: http://gulf.ifas.ufl.edu.