FOR IMMEDIATE RELEASE: THE WEEK OF JANUARY 15, 2006

COMMUNITY FORESTRY ISSUES - WINTER ICE DAMAGE

Winter weather with freezing rain and ice has once again damaged trees in several areas of the state. Ice accumulation on branches and twigs creates massive weight far greater than many trees can support without breakage. Wind, in ice-laden trees, can compound the problem. Every ice storm of significance separates the “hard-wooded” more durable trees from their “soft-wooded” cousins. Trees such as Siberian elm, silver maple and willow may sustain much damage while the oaks, for example, have little or no damage. Oaks that have retained winter leaves have much more surface area on which ice can form, but even with that added load, branches will often recover once the ice weight melts.

A properly pruned tree will suffer less ice damage as will a tree that has wide-angle branch attachment. Narrow-angled branch and scaffold limb crotches are weak and subject to ice or wind breakage. One of the characteristics of “weak-wooded” trees is that they commonly have narrow-angled crotches. Pruning may help correct this problem, but in many cases the characteristics is in the genetics of the tree and cannot be corrected. It is advisable to select a tree in the nursery that displays a wide-angle branch attachment.

Ice-laden trees usually appear to be more damaged than they actually are. Prune only broken limbs at first, allowing time for branches to recover and assume their normal positions in the tree. Branches that exhibit internal breakage or severe enough damage that they do not assume their normal positions after several weeks may be removed later if need be. Don’t do any work on your tree, other than emergency work, until the ice has melted.

A recent study by the Forestry Department at the University of Illinois in Urbana suggests that tree shape and branching pattern have a role to play in its susceptibility to ice damage. Their study suggests that trees that are pyramidal or conical in shape with low branches surface areas that is, short branches such as occur in arborvitae, pine, and cedar are less susceptible to damage than trees with open crowns and extensive branch systems. In my experience, evergreens such as those just mentioned are very susceptible to damage because of extensive amounts of surface area on which ice can form and a weaker wood structure than many deciduous trees. Listed below are some common trees and their degree of susceptibility to ice damage based upon my observations over the years:

Susceptible

Siberian elm

Japanese pagoda tree

Bradford pear

Silver maple

Pine

Arborvitae

Willow

Ash, white and green

Hackberry

Sugar maple

Linden

Red maple

Sweet gun

Ky. coffee tree

Walnut

Red bud

Most small flowering trees

Red cedar

American sycamore

Resistant

Oaks, all species

Honeylocust

Osage orange

In Kansas, ice and wind damage are to be expected. It just sort of goes with living here. Such storms however, serve as good reminders to select and plant trees that exhibit strong tendencies to withstand such weather.