Sun blister is freezing stem skin after high temperatures in winter, resulting in permanent damage to bark. Fruits can also be damaged. In the northern hemisphere, it's also called southwestern injury .
Video Sun scald
Cause
The reason the sun can cause much damage to trees is due to dormancy. When a tree is off in winter it can be reactivated by warm weather. In the northern forest trees are exposed to the most sunlight and heat on the southwest facing side, so this side is heated during the sunny winter days to the point that can awaken from dormancy. The temperature required to build a tree depends on the plant species and the length of the day, but usually just above freezing. Once active, cells on the southwestern side of the plant can not return to dormancy at night, when the temperature returns to levels capable of killing the active cells. Fluctuating winter temperatures can also cause ice cracks, resulting from the expansion and shrinking of tree trunks.
Maps Sun scald
Tree
When sun scald appears in the trees, it is most often the result of light reflection from the snow during winter. Damage in this case will look like a concave or dead skin on a tree trunk, then at the age of the tree, the bark will fall and show dead tissue in the cambium layer of the tree. This damage will usually be found on the south west side facing the tree trunk. This can be found on the other side of the tree if there is a reflection of light from other sources, such as man-made structures or bouncing stone faces. Once the tree is exposed to sunlight, it becomes much more susceptible to decomposing organisms. The plant will make a wall around the affected area, but sometimes not enough to block the infection. The leaves of the tree are also affected by sunlight, especially on a sunny day after a period of warm cloudy humidity. Damage to the leaves will begin as bronzing from the epidermis between the leaf veins, and if the sunny conditions persist the leaf tissue will die.
Fruits
Sun blistering on the fruit appears when the fruit is exposed to direct sunlight after being in the shade for a long period of time. Fruit damage will often lead to the death of the fruit by the consumption of insects, animals, bacteria, or fungi. This is the case if the defense of the fruit becomes useless, which is the case when the outer shell is damaged to the point that the cell wall is lost, or so thin that the plant enemies get through it. Several times the boiling sun is more internal damage and, though it destroys the fruit in a productive sense, it is able to fend off attacks and recover if placed back into the ideal setting.
Treatment
The treatment of boiling sun is basically simple: reduce the intensity of the sun, or block the sun completely.
Wrapping
The most common method used to prevent the sun's heat on a tree trunk is by wrapping the tree into the first branch with a white paper that overlaps about thirty-three percent each time around the tree. White paper is effective in reflecting the sun's heat from the tree. The paper should be applied after the tree is inactive during winter and removed before it becomes active again. If the paper is left too long it can interfere with tree growth and protect insects that can damage trees.
Painting
Painting white trees has the same effect as wrapping, even though it is a permanent change in tree color. These color changes can be aesthetically unpleasant, so this method is widely used in gardens and rarely in the landscape.
Shading
The amount of light the tree receives on the southwest side correlates with the amount of sun that coats the tree. Reducing the amount of light exposed by trees by strategically planting shrubs or shrubs to the shade of the southwest side can be less effective than wrapping or painting, but can have better aesthetic qualities for landscaping.
Fruits
For fruit, the most important part of avoiding sunlight is to realize where the fruit is during its growth. If the fruit grows in the shade then exposes it to the sun it will tend to produce damage to the product. Because of the importance of keeping fruits shaded from the sun, the leaves of fruit plants should be monitored for withering and disease. If the leaves that shade the fruit die, the fruit will open and threatened by the sun. Another measure that can be taken to avoid damage is to cover the fruit with straw or a screen to block out the sun.
See also
- Ice crep
References
External links
- Video footage and comments about Sun Scald and Frost Crack
- Clemson University Cooperative Extension Service, Tomato Disease.
- Colorado State University Extension Services website. Sun Scald of Trees
- The Michigan State University website
- The North Carolina State University website. Tree Anatomy.
- Purdue Plant and Diagnostic Laboratory.
- Research and Expansion of Kansas Sunscald State University, Crack in Baggage, Sun Scald,
- University of Saskatchewan, Dormancy In Plants: A Process To Survive,
Source of the article : Wikipedia
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