Bark cracks

Bark cracks can have several causes.

Recognize damage to the bark of a tree
Bark cracks, photo: Saundra Winokur

Bark cracks may have several causes:
Frost crack: at night, water freezes in the bark, with the pressure of the frozen water (ice takes up more space than water) causing the bark to burst open. A second possibility is that if the bark alternately shrinks during frost and expands on hot days, cracks appear. A tree with a frost crack is in no danger and may live for several years.
Torsion: this is especially common in fruit trees (apples, pears, plums) whose branches are full of fruit. The branches can become so heavy that the branch cracks from the trunk or vertical (torsion) cracks in the trunk.
Lightning strike: often then, not only is there a crack, but the trunk (usually of large, mature trees) is completely cleaved.
Sun: some trees (lime tree, beech) are sensitive to sunburn, causing the bark to crack. Sunburn is caused by a combination of strong sun, high temperature and drought stress of the tree, causing the temperature of the bark rising too much (> 40°C) and tissue damage occurs.

Trees with thin bark are susceptible to cracking.

Where to find

  • Fruit trees
  • Lime tree
  • Beech

Remedy

Not all cracks need to be treated: growth cracks are generally harmless. Really open cracked bark may be treated with wound balm. Cracks due to sunburn should be scratched clean and treated with wound balm.

Prevention

Sunburn at a lime tree and beech may be prevented by wrapping the trunk with burlap at planting. This should also be done if pruning suddenly exposed part of the trunk to the summer sun.