Sunscald

Problem type: Environmental

Name of problem: Sunscald

Plant name(s): Young, thin-barked deciduous and coniferous trees, including fruit plants

Symptoms / Characteristics:
Affected trees and branches typically show symptoms on the south or southwest side of the main stem. Damaged bark appears reddish in early spring and fades to dark red or brown later in the summer. Sunscald may also cause a vertical split in the bark on the exposed side of the tree. During late winter or early spring, the low-angle sun causes a substantial increase in the bark temperature during the day relative to the air around it. At night, the temperature drops dramatically, causing damage to the bark cells. The bark may shrink, weaken and fall off. Dead bark cells inhibit water conduction within the tree, which may result in top dieback. Damaged bark also renders the tree vulnerable to secondary disease or insect attacks.

Control / Preventions:
Use nursery recommended wraps to shade the trunk during winter and keep the bark temperature cool. Young or newly planted trees should be protected for at least the first two winters. Wraps must be removed in the spring to prevent girdling and also to reduce the potential for insect and disease pests. Shade can also be achieved by planting low-growing evergreens around the base of the tree. Avoid pruning low-hanging branches as these also provide winter protection. Also avoid planting young, thin-barked trees on the south or west sides of buildings in order to reduce exposure to full sun.