Wrapping the trunks of small trees in your yard (PDF) - University of ...

Greenwald 2013
Red maples are susceptible to winter frost cracking and sunscald
t is a common sight to see red maples along a walking path or sidewalk in an urban setting with one side of
the bark damaged and cracked. When I was going to school at Missouri State University in Springfield,
Missouri, there was one maple in particular which I passed every morning that seemed to be eaten away on
one side; with only a thin section of the trunk and bark remaining. The cause of this ailment was not a living
disease, but actually the environment. The winter is a harsh time of year and can put a great deal of stress on
sapling trees with thin bark. This week’s article is on protecting trees from the harsh effects of fluctuating
winter temperatures.
Has a the bark of a young red maple, fruit tree, or other thin bark tree in your yard appeared to crack and split
on the southwest side during the winter leaving it gashed and callused? Just like the tree I passed in
Springfield, this damage to the southwestern side of thin barked trees is called sunscald injury and is caused by
warm winter sunlight and temperature fluctuations.
The problem is that during the late winter, in the Missouri Ozarks
we tend to have drastic temperature swings all within a few hours
of time, it can be sunny and 63 degrees one afternoon, and 28 the
next with temperatures dropping to 16 degrees at night. These
changes in temperature place stress on the cells under the bark of
the trees, especially thin barked trees like red maple. This stress is
often is too much for even cold hardy native tree species to
endure without damage. According to Colorado State Extension,
sunscald injury is most prevalent on the southwestern side of
trees because that is the side of the tree which receives the most
sunlight and when it warms that side of the tree is tricked into
breaking dormancy, only to be devastated when temperatures
plummets and its bark cools to actually normal frigid
temperatures.
Stressed trees whose cells have been damaged by the warm to
cold temperature changes can appear as if their bark has been
Cracked and pealing bark is a
symptom of winter sunscald
damage.

Greenwald 2013
gashed, and cut as other necrotic callused tissue forms. Trees which do not succumb to disease pressure from
these open wounds, survive for years to come in this damage state.
Utah State University Extension recommends wrapping trees in the fall with white tree wrap to prevent the
bark of the trees facing southwest from warming too much in the late winter; helping to keep the bark cool,
dormant, and free of cracks and dead damage tissue. When wrapping a young southern magnolia back home, I
tucked the corner of the warp securely under itself to hold it in place. Since our last frost is around April 15 th -
20 th , wait to remove the warp till after this date.
If the proper step is taken to limit winter cold injury to small trees, southwest injury and frost cracks can be
avoided. 12
1 http://extension.usu.edu/files/publications/factsheet/nr_ff_021pr.pdf
2 http://www.ext.colostate.edu/ptlk/2111.html