Trees can be expensive and are valuable plants we need to avoid injuring. Wounds are openings for decay organisms and trees expend energy for wound sealing, setting them up for other issues. During winter, protect young trees from excess mulch, staking materials, temperature extremes, and wildlife.
If you have a tree with mulch piled against the base, pull the mulch six inches away from the trunk. Mulch piled against a tree can become winter cover for rodents, like voles and mice, who gnaw on trees during winter and girdle stems.
Mulch piled against trunks increases moisture near the root flare enhancing the risk of decay. Moisture and wood are attractive environments to carpenter ants who could establish nests in a tree, especially if there is a wound and decay has set in. Carpenter ants do not eat wood, but can spread decay.
If trees are surrounded by landscape fabric and rock mulch, check the trunk base. Both can constrict and girdle trunks leading to chronic stress or dieback. As a tree grows, rock mulch needs to be moved away from the trunk and landscape fabric cut away so these are not touching the tree.
If young trees have stakes and guying materials, check to see these are not rubbing against the trunk or branches and causing wounds. Ideally, only stake trees for one year after planting.
While tree wraps are recommended to reduce frost cracks, research shows avoiding trunk wounds can be as or more helpful than wraps. Vertical frost cracks often start at the site of a wound. While these rarely kill a tree, they’re openings for decay organisms. Follow previous recommendations to avoid wounds.
Young or thin barked trees are wrapped during winter to reduce frost cracks and sunscald. Use a light-colored wrap to reflect light and reduce trunk warming. Starting near the base, wrap upward overlapping the wrap. Tree wraps need to be removed each spring to avoid damaging the trunk as it expands in size.
Voles are small, mouse-like rodents that do not hibernate. The most economic damage they do is feeding on and girdling young trees. While not harmful to lawns, they will nibble on turfgrass beneath snow creating surface runs that recover with spring growth. Tree damage is a much larger concern.
Along with keeping mulch away from tree trunks, also keep weedy areas mowed and tall grass away from trees. Don’t damage the trunk with mowers or weed trimmers. Voles are often attracted to spilled bird seed. Removing or limiting this food source can help reduce vole populations.
To protect trees from vole and rabbit feeding, exclusion works best. Wrap tree trunks with a cylinder of one-fourth inch hardware cloth. Insert the cylinder a few inches into the soil to avoid voles accessing trees from underneath. Use at least two-foot tall cylinders to protect tree trunks from rabbits.
Deer are difficult to exclude. Taste or smell repellants can be applied to trees to deter feeding. Use those labeled for such use and follow directions. Repellants need to be reapplied since they wear off. The label will provide the reapplication period to follow and conditions under which the product can be applied.
Trees are wounded when ice or snow leads to branch breakage. If heavy snow builds up on branches, carefully sweep it off rather than hitting the branch to knock it off. Let ice melt naturally. If a branch breaks, remove it where it is attached to the trunk or another branch. Do not leave a stub. This is a wound a tree cannot seal and decay will develop in the stub and enter the trunk.
If you have a specimen evergreen in a key location, the branches can be carefully tied up to avoid snow building up on the limbs and weighing them down.
By: Kelly Feehan, Extension Educator
Release: Week of December 9, 2024