Can Arborvitae Survive an Ice Storm?

A resounding boom during an ice storm often means that a tree has suffered significant damage and dropped a limb. Many factors -- including branching habit and general tree form -- contribute to ice storm damage in any tree. Arborvitae can survive an ice storm if left alone, but efforts to discourage ice accumulation on its delicate branches will go a long way to ensuring the tree is fully intact come spring.

Prepare for Winter

If you live in an ice-prone area, preparing trees for ice from the time they are planted is critical. Prune for crotch angles of 45 to 90 degrees between the trunk and the base of each branch. Shallow crotch angles tend to be weaker and will split under pressures such as those created by ice accumulation.

When Ice Looms

When icy weather is threatening, you should take precautions to protect small trees. Conical trees such as arborvitae should be bound so that each tree forms a loose upright bundle; this provides additional support to weak crotches. Using carpet, strong cloth or nylon, wrap the trees snugly from one-third of the way up the tree to the top. Be sure to remove coverings whenever possible, as leaving them can cause girdling.

Thawing Out

Leaving ice on trees after a storm is a recipe for disaster. Even though the branches escaped being snapped as ice was accumulating, there is no way to know if the weight of that ice will snap the branch later. Remove heavy ice accumulations as soon as is reasonable, even if temperatures are still below freezing; the weight of so much ice may cause more damage if left until temperatures are above freezing. Start by gently brushing snow up and over bent-over branches. If the ice does not melt on its own after snow removal, apply warm water to the tree limbs using a garden hose until most of the ice is gone.

Repairing Ice Damage

Once the ice is clear, assess the tree's general condition. If ice accumulation revealed significant internal damage such as rot, it may be best to cut the tree down. Severely damaged tops need also to be assessed. However, if the tree is in reasonable repair and is only suffering broken or damaged limbs, it can generally be saved. Remove all broken limbs by cutting them back to the nearest strong branch. For bark damage, cut away any ragged bark edges into the nearest healthy bark. The cut should be football-shaped, with the pointed edges running vertically. Cut parallel to the damage where a vertical cut would be excessive.

References

• Ohio State University: Ice Storms Can Point Out Flaws in Trees
• University of Minnesota Extension; Protecting Trees and Shrubs Against Winter Damage; Bert T. Swanson, et al.; 2009
• University of Illinois Extension; Ice, Snow, and Salt; Jeff Rugg; February 2009
• University of Illinois Extension; How to Care for Ice-Damaged Trees; Ron Wolford; 2011