Landscape - Winter Leaf Burn

With winter fast approaching, landscape plants can be exposed to winter injury. One such injury is foliage "burn". The following is more information.

Foliage on broad-leaved evergreen species, like rhododendrons and boxwood, as well as with narrowleaved evergreen species, like yews, arborvitae, and hemlock, may suffer desiccation during winter. Drying winds and bright sunlight may dry out the foliage. Even when the ground is frozen, plants, both deciduous and evergreen, require moisture during winter. When the ground is frozen and the root system is insufficient enough to supply water to the tops of the plants, the foliage will dry out resulting in brown, dry leaves that start at the edges or needle tips that later fall off in spring. Foliage on broadleaved evergreens can heat up to 50°F or more during sunny days in winter, causing tissue deacclimation. When the sun sets and temperatures drop sharply, the leaf tissue freezes rapidly causing death. The leaves on the outside of the plant and leaves facing the south, west, or southwest side of the plant will be most affected. The sun, as well as the harsh winter winds, causes the injury.

Information from "Winter Injury and Winter Protection of Woody Ornamental Plants" by Dr. Laura G. Jull, Department of Horticulture, University of Wisconsin–Madison
http://www.waa-isa.org/pdf/NovDec2008/NovDec08-TreeLore.pdf