FARGO -- Tree wraps are important for protecting young trees against winter damage, but they shouldn’t be left on all year. Be kind to your young trees and remove wraps each spring.
When they’re applied in the fall, tree wraps shelter tender young bark from animals and sunscald.
Sunscald damages bark when the winter sunshine reflects off of snow, causing a thawing/freezing injury similar to the way skiers can get sunburn from winter snow.
Tree wraps shade and protect bark from the winter sun. This is especially important when trees are young, and the bark is smooth and thin.
As trees age, the bark becomes thicker with raised ridges. This makes trees less susceptible to winter bark injury as they get older, and tree wraps are less important then.
Some tree types continue to have thinner bark even as they age.
Fruit trees, maples and lindens have thinner, smoother bark that benefits from wrapping for more years.
As beneficial as tree wraps are for protection, they need to be removed each spring. If tree wraps are left on during the spring and summer, they can damage trees.
Tree wrap left on too long caused constriction and indentations in the trunk.
Damage can be caused in several ways.
If the wrap is in close contact with the tree, the wrap can exert pressure on the tree trunk, as the tree is trying to grow and expand with spring’s growth.
The pressure of contact can cause the tree to be choked and girdled, causing severe damage.
There are many trees especially on commercial properties where tree wraps have been left on for too many years, and the constriction is causing tree decline.
Trees can also be damaged by tree wraps that remain all summer, even if the wraps are loose with space between the wrap and the trunk.
Wraps, even if loose, can cause the tree trunk to remain overly moist, which encourages insects and disease. Removing even loose wraps allows the trunk to breathe with good air circulation and exposure to sunshine.
In summary, tree wraps are best applied each fall (November) and removed each spring (April).
This will keep our young trees perky and healthy.
Kinzler is a lifelong gardener who worked as an NDSU Extension horticulturist and owned Kinzler's Greenhouse in Fargo. Read more at growingtogether.areavoices.com.