CORVALLIS - Winter ice storms can wreck havoc on landscape trees. The weight of accumulating ice can bend and break limbs, especially on susceptible trees that are weakened or poorly pruned to begin with.
Many factors influence the response of trees to ice storms, according to Sven Svenson, assistant professor of horticulture at Oregon State University's North Willamette Research and Extension Center. Some species or cultivars are generally more resistant than others to damage during ice storms.
Generally, conifers are more resistant to ice damage than deciduous trees, according to Svenson, and spruces and firs are typically more resistant than pines. Deciduous tree species with strong wood and well-attached branches, such as most oaks, hickories and ginkgos, are able to weather ice storms better than those with soft wood and narrow crotch angles, such as European birches, Bradford pears and many maples. Cultivars of some species are available with strongly upright, columnar growth habits. Such trees, with good branching habit, can be quite resistant to ice storm damage.
However, a properly pruned maple may resist damage better than a poorly pruned oak.
"Remember that selection of an ice damage-resistant tree does not guarantee a tree will not be damaged by ice," warns Svenson. "Proper site selection and timely tree care must be practiced to maximize the tree's resistant characteristics."
To begin your search for ice-storm resistant trees, Svenson recommends the following list for the Willamette Valley. This list is under continuous review and will be regularly modified based on new information. Ask nurserymen about improved selections with known resistance to ice-damage.
Fir (many species and cultivars)
Blue Beech, Carolina Beech
Cypress (many species and cultivars)
Ginkgo, Maidenhair tree
Spruces (many species and cultivars)
Douglas-fir (many cultivars)
Swamp White Oak
Western Red Cedar, Arborvitae