Cover your losses with ice storm-resistant trees

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.

Name(s)

Abies sp.

Fir (many species and cultivars)

Acer circinatum

Vine Maple

Acer griseum

Paperbark Maple

Arbutus menziesii

Madrone

Calocedrus decurrens

Incense Cedar

Carpinus caroliniana

Blue Beech, Carolina Beech

Carya sp.

Hickory

Chamaecyparis sp.

Cypress (many species and cultivars)

Chrysolepis chrysophylla

Chinquapin

Ginkgo biloba

Ginkgo, Maidenhair tree

Juglans nigra

Black Walnut

Ostrya virginiana

Ironwood

Picea sp.

Spruces (many species and cultivars)

Pseudotsuga menziesii

Douglas-fir (many cultivars)

Quercus alba

White Oak

Quercus bicolor

Swamp White Oak

Quercus garryana

Garry Oak

Taxus sp.

Yews

Thuja plicata

Western Red Cedar, Arborvitae

Tilia cordata

Littleleaf Linden

Tsuga sp.

Hemlocks

Umbellularia californica

Oregon Myrtle