Ask Mr. Smarty Plants

Here's a bit of the information that we have on our website about Silver maple (Acer saccharinum), a soft maple. Large tree with short, stout trunk, few large forks, spreading, open, irregular crown of long, curving branches, and graceful cut-leaves. A large canopy tree, 75-100 ft. tall, silver maple’s massive, ascending limbs form a graceful, oval or rounded crown. Plump, red flower buds are visible in winter and the first to bloom in spring. Deeply-cut, deciduous leaves are silvery underneath. Fall color ranges from yellow-brown to yellow tinged with bright red. Its rapid growth makes Silver Maple a popular shade tree; however, its form is not generally pleasing, its brittle branches are easily broken in windstorms, and the abundant fruit produces litter. Sugar can be obtained from the sweetish sap, but yield is low. Landscape value should be tempered as it becomes a liability with age. Silver maple sap is only half as sweet as that of sugar maple (Acer saccharum), but with patient boiling it yields a delicious pale syrup. Will cause sidewalks to buckle and drain tiles to clog. Should be considered in areas of poor soils where few other species will survive.

Texas AgriLife Extension has some good information on their website about Tree Wounds by Wayne K. Clatterbuck. He says... Tree wounds are common and the causes include: broken branches; impacts, abrasions and scrapes; animal damage; insect attack; fire; etc. Wounds usually break the bark and damage the food and water conducting tissues. Wounds also expose the inside of the tree to organisms, primarily bacteria and fungi that may infect and cause discoloration and decay of the wood. Decay can result in structurally weakened tree stems and can shorten the life of a tree. Decay cannot be cured. However, proper tree care can limit the progress of decay in an injured tree.

Proper care of tree wounds encourages callus growth and wound closure. Research indicates that wound dressings (materials such as tar or paint) do not prevent decay and may even interfere with wound closure. Wound dressings can have the following detrimental effects:

• Prevent drying and encourage fungal growth
• Interfere with formation of wound wood or callus tissue
• Inhibit compartmentalization
• Possibly serve as a food source for pathogens

For these reasons, applying wound dressings is not recommended. Trees, like many organisms, have their own mechanisms to deter the spread of decay organisms, insects and disease.

Filling large holes or hollows in the tree is generally done for cosmetic reasons. There is little data to indicate that a filled tree has better mechanical stability. However, fillings may give the callus tissue a place to seat, thus stopping the in-roll (folding) of the callus. Almost any filling can be used as long as it does not abrade the inside of the tree.

Filling a tree cavity is generally expensive and not recommended. Filling does not stop decay and often during the cleaning of the cavity, the boundary that separates the sound wood or the callus growth from the decayed wood is ruptured. Thus, this cleaning for cavity filling can have more detrimental effects on the tree than if it were left alone. Care must be taken not to damage the new callus tissue that has formed in response to the tree damage and subsequent decay.

Proper pruning should be used to remove dead, dying and broken branches; to remove low, crossing or hazardous branches; and to control the size of the tree. However, pruning of any kind places some stress on the tree by removing food-producing leaves (if the branch is alive), creating wounds that require energy to seal, and providing possible entry points for disease.

Pruning cuts should be made to maximize the tree’s ability to close its wound and defend itself from infection. When pruning, make clean, smooth cuts. Do not leave branch stubs. Leave a small collar of wood at the base of the branch. The branch collar is a slightly swollen area where the branch attaches to the trunk. Cutting the limb flush with the trunk will leave a larger area to callus over and a greater chance of decay organisms entering the wound. The optimal pruning time is in the winter (dormant season) when temperatures and infection rates are lower and when trees are not actively growing.

In conclusion, healthy trees usually recover from wounding quickly. Try to keep wounded trees growing vigorously by watering them during droughts and providing proper fertilization. This will increase the rate of wound closure, enhance callus growth and improve the resistance to decay mechanisms.