Although moisture, feeding and insect control are important for our landscaping plants, bushes and trees, they also need to be protected from other threats. One of these threats is a condition known as sun scald.
What is Sun Scald?
Often, during the winter, there will be a few days of pleasantly warm weather where the temperatures will rise above freezing and the sun shines very warmly. These conditions usually affect the southwestern side of the tree trunk or bush, although it can occur on any side if snow cover compounds the affect by reflecting the sun back onto the tree.
As the sun’s warmth strikes the tree for a few days, the affected areas lose the protection of their dormancy. When the warm period succumbs to the cold of winter again, the sun-warmed parts of the tree cannot become dormant fast enough to avoid damage from freezing.
While most sun scald damage on trees occurs during the winter, other plants, fruits and foliage can experience sun scald during the growing season. This type of sun scald usually appears when protective shade or neighboring plants are removed, exposing areas of the vegetation to direct sunlight for the first time.
Recognizing Damage From Sun Scald
- On trees, sun scald often appears as dead or dying bark on a tree, or an area that appears sunken. This usually occurs on the south side of the tree and can also be complicated by the shedding of the bark and increased insect activity in the area.
- Foliage that has been scalded by the sun may appear to be wilting, or dying and may become bronzed in color.
- Sun scalded fruit can appear as damaged or discolored areas and often have increased insect activity.
Preventing Sun Scald
Preventing sun scald is done by taking steps to block the rays of the sun, or reduce their intensity. For trees, this can be accomplished by wrapping the trunks with white paper to reflect the sun’s rays during the dormant period. Painting the tree trunk with white paint can also be effective, however this cannot be removed and can alter the aesthetic value of the tree.
Shading can be the best option for smaller plants, trees and bushes by planting additional vegetation capable of providing shade and insulation value to the susceptible plants. For temporary protection, low growing plants can be covered with straw for a short time to prevent damage.
Careful attention to the pruning and placement of plants, trees and bushes can also be an effective way to prevent this unattractive problem and keep landscaping as healthy and vibrant as possible.
Sources:
http://www.colostate.edu/Depts/CoopExt/4DMG/Trees/sunscald.htm, http://www.gardeningknowhow.com/plant-problems/environmental/sunscald-on-plants.htm
