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Sunscald 

 
Fig. 267 
Coppery red bark of an immature Douglas-fir affected by sunscald.		 Fig. 268  
Necrotic lesion caused by sunscald. 		Fig. 269 
Sunscald-killed Douglas-fir. Damage may be more frequent along perimeter of dry, exposed sites.

Distribution:  Throughout B.C. wherever temperatures from insolation reach levels high enough to kill the cambium in young trees.

Tree Species Affected: Young trees of any species are susceptible, particularly Douglas-fir.

Signs & Symptoms: The southwest side of the main stem of young trees is generally most affected. The outer bark on the stems of recently damaged trees is coppery to bright red. Older damage is a darker red to brown colour. This discolouration fades by the end of summer. Dead bark shrinks, becomes loose, and sloughs off. Sunscald cankers may vary from small patches to large areas extending almost the entire length of the exposed stem. Injured areas are confined to smooth, unfissured sections of the bark. Damaged trees are commonly seen in summer on droughty sites or in areas where thinning or pruning has been carried out, since these conditions expose shade-grown trees to the effects of intense direct sunlight. Rapidly growing trees may also be affected. Sunscald incidence is often greater along the open or southern-exposure edges of a stand.

Damage: Areas of dead bark may allow the entry of decay-causing fungi. Significant growth loss or mortality is seldom directly attributable to sunscald. Damaged trees may be more susceptible to root diseases like armillaria and black stain.

Similar Damage: Dermea and phomopsis cankers may be confused with sunscald damage. However, no fruiting bodies are present, and sunscald damage is generally confined to the southwest side of the stem.

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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