Abstract

Abstract

HAMILTON, W.D. 1987. Tree wounds: their cause and treatment. Arbor Age 6(10):36-39.

Tree wounds are natural in the life of every tree. Scars left by fallen leaves, stubs left by fallen dead branches, and holes made by wildlife are part of tree life. A tree wound is any injury which damages living bark; cambium and wood may also be involved. Bacteria and non-decay fungi are the first to colonize the wood surface. Few of these can grow into wood: usually they are not wound invaders. Organisms that do grow into the wood are faced with chemical protective barriers (phenolic compounds) formed by the tree. Some surmount the barrier: most cannot. Upon examination of decay in tree wounds, it is evident that the whole cross section of a branch or trunk is rarely involved. Usually, there are limits to decay from a particular wound. The size of the wound may be large if pruning cuts are made flush with the trunk, and small but slow to heal if a long stub is left. So a compromise is made. The cut is made on the outside edge of the shoulder tissue, slightly away from the larger limb. Normally, this will be just outside the protective barrier formed by the tree. Late fall and early winter may be the worst time for wounding, due to the abundance of fungal spores. At present there is no proven means of increasing the rate of wound closure other than increasing tree vigor.