Winter’s icy hand has wrapped its bony fingers around your trees, and with its cold grip comes a host of new concerns.
Whether it’s bitter cold, like the 2014 Polar Vortex, or more unsuspecting threats, like liability trees, you can watch for signs of damage from these winter issues and take curative steps to keep your trees healthy until warmer temperatures return.
Extended below freezing and sub-zero temperatures, like those from the polar vortex, can have a number of effects on tree health. Effects range from frozen soil, lack of moisture and damage to thin bark.
Winter burn, or desiccation injury, happens when roots cannot absorb sufficient water to keep up with the amount of moisture leaves lose. This problem most frequently affects evergreen trees and shrubs because they continue to evaporate existing moisture in the wind—water that cannot be replaced from the frozen soil below.
Frost cracks happen when the temperature differential between sun-warmed bark and super cold air is magnified. This typically affects thin-barked trees.
Soil heaving happens when the soil alternates between freezing and thawing and pushes shallow plant roots out above the ground surface. This exposes them to cold, dry winds.
R.J. Laverne, an ISA board-certified master arborist with The Davey Tree Expert Company, said a late spring frost can actually cause more damage than an extended period of freezing temperatures.
"Trees are already dormant, so (a) polar freeze will have a little long-term effect," Laverne said. "All the prep work, such as mulching and good watering, needed to be done in the fall, so as long as (property) owners did that their trees should suffer little damage from frigid temperatures."
Pruning is the cornerstone of any successful tree care program. Tree managers should prune for shape, structure and health, in addition to removing dead, diseased or unsafe branches.
"Many people think that trees need to be pruned in the middle of the growing season so they can tell which branches are dead or alive, but that isn't so," Greg Mazur, Davey Tree’s tech advisor, said. "A trained arborist can tell in winter which branches are dead or alive and can remove the right branches in order to properly shape a tree and get it away from a roofline."
In winter you may have to remove critical risk trees. What you need to do is determine if a tree has transformed from an asset to a liability. A certified arborist can help you conduct a tree risk assessment to make that determination.