Trees, shrubs and winter: an arborist’s take on all things snow

PHOTOS PROVIDED Damage on a young tree, left, caused by rabbits chewing the bark on the lower stem.

Heavy snows, wind, ice and rain. That’s winter. It’s not uncommon to see a lot of limbs down on properties after serious winter storms. Cleanup takes care of the debris, but an arborist should make a careful inspection of the trees and shrubs on their client’s property to ensure that the damage they have sustained during the harsh weather will not cause problems later.

Heavy snows may have injured the trunks and branches of trees. Splits may occur in multi-stemmed plants that may need cabling and bracing or pruning to eliminate the weakened branches. Leaning trees, trees that are subject to high wind loading (top heavy) or trees on sloping ground could be susceptible to root failure. The buttress roots should be inspected carefully.

Winter drying generally affects evergreens, usually broadleaf evergreens such as mountain laurel, rhododendron, azalea and holly. Yew, arborvitae and chamaecyparis also are commonly affected. This injury results from transpirational moisture loss during the warm days in the winter when the soil is frozen. Water lost through the foliage is not replaced from the frozen soil, which results in desiccation of the foliage.

Frost cracks generally occur on young thin-barked trees such as maple, sycamore, zelkova and linden. This injury generally results from sudden drop in temperatures from a sunny, daytime high to very low, nighttime temperatures. It is believed that this sudden shrinkage results from water moving out of cells and freezing during sudden drops in temperature. The wood closest to the surface shrinks as water is lost quickly while the inner wood is not affected. The sudden change creates pressure between those two zones resulting in wood cracking.

The salt (sodium chloride) commonly used as a de-icing agent on roads and walkways in winter can cause serious injury to plants. High levels of salt in the soil from pavement runoff can desiccate and kill plant roots. Sodium can be toxic to plants and can also destroy soil structure, leading to compaction and elevated soil pH. Salt spray can desiccate foliage and buds on plants adjacent to roadways. Symptoms of salt injury are visible as a progressive decline in plant vigor. Leaves become dwarfed and chlorotic or brown, shoot growth is reduced, leaves become tufted on branch tips and the crown appears thin. In some cases, twig and branch dieback occurs and plants eventually die.

PHOTO PROVIDED Winter damage on a rhododendron can be seen as dieback of the leaf margin all the way up to full leaf necrosis. Winter damage can be more prevalent when root rot is present, especially on rhododendron.

Deer browse can cause severe injury to foliage and twigs of landscape plants, especially in snowy winters. Exposed stems of small-diameter trees can be damaged or destroyed by “buck rub,” the scraping of antlers against the trunk.

The lower stem and root collar of plants can be damaged and even girdled by rabbits and rodents that eat the bark tissues. Plants that have stems girdled by animals often wilt and die suddenly in late spring or early summer after new growth begins.

It’s worthwhile to protect your investment in your landscape with inspections to avoid expensive tree and shrub replacements later on. A program of managed health care for trees and shrubs involves regular inspections throughout the year by a professional arborist — to identify and correct conditions before they reach the “crisis” stage.

Cody Kouneski is an arborist representative with Penn State Mont Alto Forestry and an International Society of Arboriculture Certified Arborist.


Today's breaking news and more in your inbox

I'm interested in (please check all that apply)
Are you a paying subscriber to the newspaper? *

Starting at $4.62/week.

Subscribe Today