Summer is an excellent time to prune many ornamental trees. Among the more popular species are the numerous varieties of Japanese maples that grace many Puget Sound landscapes.
Below are a few tips on how to enhance the beauty of your Japanese maples. Some of the common environmental and disease problems will also be discussed.
Pruning Tips: If your maples were not pruned during the fall or winter, now is a good time to start since most of the new growth has occurred. The best tools are good quality pruners, a small folding-type saw and some grubbies.
The secret to pruning the low-growing lace leaf varieties is to work from the inside out until the tree’s foliage is thin enough to display the intricate branch structure that forms the character of these trees. This may require assuming strange, undignified and uncomfortable positions beneath a tree.
The initial targets are dead twigs and branches. This dead material is normal and usually snaps off easily using your fingers. Larger dead branches should be cut or sawed off. Next, trim out live branches and twigs growing in strange directions that interrupt the natural “flow” of the foliage. Then concentrate on thinning out crowded small twigs and branches.
When shortening a branch, try to make a cut near a live twig that is pointing the direction you wish the new growth to follow. If removing an entire branch, make the cut were it joins a larger diameter branch or the trunk. Try not to leave stubs because they will die back, become unsightly and may become entry points for decay.
Removal of around one-third of the live foliage should be the goal. Do not count the dead wood.
Common Problems: Perhaps the most common problem is that many maples are planted too close to buildings or walkways. They look innocent when young and small, so be aware of how large a particular variety is expected to grow. Do note that some varieties do better in partial or full shade, so read labels and plant a tree where it will best thrive.
Environmental problems often cause some type of leaf scorch and leaf drop during the summer. This is usually due to lack of moisture during hot weather. Usually the trees will recover the following year. Watering the trees during the hot summer months will prevent or reduce this problem.
Japanese maples are generally insect- and disease-free. However, they are very susceptible to the verticillium wilt fungus. The signs are wilting leaves followed by twigs and branches beginning to die.
This fungus generally progresses throughout a tree over a few to several months, depending upon the variety. There is no cure. Cutting out the dead branches will not stop the spread of the disease. If a tree becomes unsightly or dies, remove it and as much of the root system as possible. Do not plant a maple species back into the same area because the fungus can persist in the soil for years.
Use caution when hiring tree trimmers: I have talked to homeowners who were horrified at the results of a pruning job – or should have been! Unless you desire a sculpted appearance of your trees and shrubs, beware of the “pruner” that is stalking your ornamental plants with hedge trimmers in hand.
Ask the pruning crew to explain or demonstrate what they plan to do. Do not take his or her word that they know how to prune a particular tree. Have a full and complete understanding of what you expect the results to look like. Be certain that language differences do not hinder this understanding.
Even if you do not know how a tree should be pruned, still ask for an explanation or demonstration. If you suspect a butcher job is a possibility, then consider hiring someone else. Qualified professional arborists are available that specialize in pruning landscape plants.
Taking the above precautions will decrease the chances of having to painfully write a check after discovering your favorite tree has been reduced to stubs. Remember that a homeowner often gets what he or she pays for.
Dennis Tompkins of Bonney Lake is a certified arborist and tree risk assessor.