Green Industry - A Knowledge Portal for Commercial Horticulture in Wisconsin (sponsored by University of Wisconsin-Extension)
Diagnostics - Problem Details
Sunscald -
Damage
Often the first symptom of sunscald is the reddish-brown discoloration of bark. Then, the bark shrinks, appearing sunken, splits and peels back in chunky patches exposing sapwood underneath. Often cankers develop. Severe sunscald may cause the entire trunk to be girdled, or only individual branches. Look for sunscald on the south, southwest or west side of trunks or branches. It most commonly affects trees suffering from water stress or young trees with thin bark. Newly planted or transplanted are most susceptible and container-grown plants are more likely to get sunscald than field-grown ones. Species particularly prone to sunscald include: Liriodendron, Acer, Tilia, Prunus, Pyrus, Malus, Juglans, and Ulmus.
Cultural Controls
Reduce likelihood of sunscald on nursery-grown trees by retaining foliage along the trunk for a few years after planting; making sure plants have a well-developed root system without significant girdling; harden plants off before planting; and provide adequate soil moisture before and after planting. For all other planting situations, avoid sunscald by planting healthy trees suited for our climate; retaining foliage on lower branches for a few years after planting; keeping soil moisture adequate; applying a 4-6" layer of coarse, organic mulch around the bases of sensitive trees (not against the trunk) to retain soil moisture, keep roots cooler and reduce reflected light and heat.
Locations Affected
Plant Environment
Scouting Season:
January - Early , January - Mid , January - Late , February - Early , February - Mid , February - Late , March - Early , March - Mid , March - Late , April - Early , April - Mid , April - Late , May - Early , May - Mid , May - Late , June - Early , June - Mid , June - Late , July - Early , July - Mid , July - Late , August - Early , August - Mid , August - Late , September - Early , September - Mid , September - Late , October - Early , October - Mid , October - Late , November - Early , November - Mid , November - Late , December - Early , December - Mid , December - Late
Plants Affected
Photos
Sunscald is particularly damaging to thin-barked trees.
Extensive sunscald on green ash (Fraxinus)