Red Belt / Winter Kill 

Fig. 260  Crown deformity and branch stripping caused by snow or hail.	Fig. 261   Leader exhibiting winter kill symptoms.	Fig. 262  Affected foliage is discoloured but remains undistorted.

Distribution:  Throughout B.C. mainly along the middle to upper portions of south to southwest slopes, and occasionally in valley bottoms.

Tree Species Affected: All conifer species of all ages are susceptible, particularly lodgepole pine.

Signs & Symptoms: Symptoms usually appear in spring as reddish-brown discolouration of foliage, which when viewed from a distance, appears as a well-defined horizontal band across a slope. Red belt is the result of a combination of climatic conditions. The unseasonable occurrence of warm, dry winds by day, followed by cold air drainage at night, leads to dessication injury. Frozen soils do not allow lost moisture to be replaced quickly enough, and affected needles discolour and are eventually shed. Symptoms are often more pronounced in the upper crown and on the sides of trees facing the prevailing wind. Unopened buds are usually not harmed.

Winter kill is a similar phenomenon that occurs on flat terrain. Symptoms on individual trees are most obvious above an often abrupt line that matches the snow level at the time of injury. 

Damage: Foliage and occasionally open buds are killed. Trees often recover from extensive defoliation but mortality may result from repeated red belt damage or destruction of all buds. Affected trees have a reduction in growth rate. Trees weakened by red belt are more susceptible to insect attack or disease. Large areas of red belt increase the fire hazard for the summer following the event.

Similar Damage: May be confused with other abiotic disorders such as drought. A distinguishing feature of red belt when it occurs on slopes is the distinct elevational banding. Consider the climatic conditions preceding the damage, and the time of year that it becomes noticeable.

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Contact Tim Ebata if you have comments on the presentation of this information.

BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated March 04, 2002