Tree wraps and guards are often sold for use on young trees. These materials provide protection from harsh environmental conditions, such as “southwest injury”. This type of injury, also sometimes called “trunk scald”, occurs on the lower portion of the trunk during winter. Sunlight (at a low angle in the winter) elevates trunk tissue temperatures during the day but they rapidly cool during the evening when the air temperature drops. Trunk cracking or splitting on the south or southwest side of the tree are common symptoms as well as sunken areas in the bark. Often, insects like flatheaded appletree borer take advantage of southwest injury to gain access to the trunk, where they intensify the injury. Tree wraps on ornamental trees with thin bark, such as red maple and ornamental cherry, may protect trunks during the winter months. Alternatively, white latex paint may be applied to the lower portion of trunks to protect from southwest injury. This type of treatment is commonly used on newly-planted peach trees to protect the trunks.
Wraps composed of waterproof crinkled kraft paper or vinyl tree guards are commonly available. Tree wraps may be applied before the first hard freeze, which occurs in late November or early December in central Missouri. When you wrap a trunk, begin at the soil line and spiral the paper around the trunk up to the first branches. Overlap the edges of each layer of the material to provide adequate trunk protection. Wraps should be removed in early April.
Vinyl guards generally have a higher initial cost, but they can be re-used for several years. They also provide protection from southwest injury and should be used as described for wraps. Guards and wraps should always be removed in early spring. While these materials can protect the trunk from lawn trimmers and mowers, they also provide a protected environment for insects and disease organisms. Moisture can collect underneath the guards during the evening and prolong the wetting period, which favors the development of trunk diseases. Also, wraps prevent the penetration of spray materials and guards limit coverage of pest control products. Dogwood borers and lesser peach tree borers can cause significant trunk damage when tree guards are left on during the growing season. Additionally, materials left on too long can restrict tree growth. While wraps and guards are inexpensive and easy to use, they can detrimental to long-term tree health when not removed after a few months. Often, ornamental trees have abnormally thin bark due to bark shading in the nursery fields where they are grown. If landscape trees are planted in spring it is a good idea to leave the trunk unwrapped until fall to allow the bark to thicken. Then, remove the wrap when growth begins the following spring.
REVISED: August 1, 2012