Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001640
11/12/99
Frost cracks
A frost crack is a long, deep, narrow crack (Vis. 1) running
up and down the trunk of a tree. The crack is usually on
the south or southwest side of the trunk but can occur on
any side. Young trees or older trees with smooth bark are
most susceptible.
The crack occurs when the sun warms the trunk in winter,
causing tissues to expand. When clouds or buildings block
the sun or at sunset, the temperature of the trunk drops
abruptly to that of the surrounding air and the trunk
contracts. The outer part of the trunk cools and
contracts faster than the inner tissues. This difference
in contraction rates causes the outer trunk to crack from
the inside to the outside.
Prevent frost cracks by wrapping young trees with paper
tree wrap. The wrap should start at ground level and go
all the way up to the first main branches. Fruit trees
are sometimes painted with white, latex paint, which
reflects the sunlight and prevents the trunk's cracking.
Once a crack occurs, nothing can be done. Fertilizing a
low vigor tree may speed up growth and close the crack
more quickly. Frost cracks can allow rots or canker
diseases to get established in the trunk.
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This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
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