The first warm days of the year can be a source of concern for gardeners. In late winter and early spring, the trunks and branches of fruit and ornamental trees can get sunburn. Bleaching the trunk beforehand is a reliable solution to this problem.
The dangers of the first thaws
The Sunburn on tree trunks most often appears in the second half of winter or early spring, when the snow cover has not yet melted and the sun is already beginning to warm up. During the day, the sun’s rays heat the bark of the tree and the reflection of light from the snow enhances this effect.
Bark cells that have been heated on the south and south-west sides of the tree come to life and begin to generate movement in these areas of the trunk. However, at night, when the temperature drops sharply, awake cells die and a burn forms.
In the damaged area, the bark turns red, yellow or reddish, it may begin to peel or crack, exposing dead tissue. In addition to the bark, the cambium, the layer of dividing cells that forms the tree’s vascular tissues, can be damaged.
Sunburn interferes with plant growth
The damage from sunburn can severely stunt growth of the tree and, in case of extensive burns, can cause the death of the plant. In addition, the cracks formed in the bark often become “bait” for pests or pathogenic fungi and bacteria.
Sunburn is especially dangerous for young trees, the bark of which has not yet matured. Trees older than 4 years are usually less susceptible to this condition, however the risk still remains, especially for fruit trees and thin-barked speciessuch as lime, rowan, etc.
The solution to the problem: The bleaching of trees
There are two main ways to deal with tree sunburn: bleaching and wrapping. However, experts note that the second method is often unable to fully protect the tree from sudden changes in temperature, which cause burns. Also, insect pests can settle under the layer of wrapping material, which also does not benefit the plant.
Whitewashing the trunk and branches is an easier and more reliable way to protect the tree from the early spring sun. A coat of white paint is not dangerous for the tree and the reflective effect prevents the trunk from heating up during the day and protects the tree from temperature fluctuations and therefore burns.
A barrier against insects
In addition, the layer of lime creates a kind of barrier against insects, making it difficult for borers and other pests to access the bark of the tree. Also, insects are much easier to spot on the white surface of the trunk.
But not all bleaching methods are equally safe and effective. The most popular remedy is a bleach based on lime diluted in a saline solution. However, this composition creates an alkaline environment, which alters the natural acidity of the tree’s bark. In addition, it is not the most harmless substance for human skin: many gardeners are faced with the fact that lime-based whitewash “corrodes” the skin of the hands.
Another less recommended alternative: #latex paint
Another popular whitewash solution is latex paint-based solutions. However, the use of such paints is not always safe; in any case, it is not recommended to use them to whiten fruit trees. In addition, the latex included in the paint has a rather dense structure, which disrupts the natural gas exchange of wood.