Why is the trunk painted white in winter?

The trunk is usually painted white, which looks neat and beautiful from a distance. However, people paint it white, mainly because they don't care about looking good.

This white thing is limewater, which is made by adding 20 kg to 40 kg of quicklime to 100 kg of water.

Brushing trees with limewater has several advantages:

First, lime has a certain bactericidal and insecticidal effect, which can kill some overwintering fungi, bacteria and pests parasitic on tree trunks.

Second, because pests generally prefer black and dirty places to white and clean places. The trunk is coated with snow-white limewater, and the pests wrapped in soil dare not climb up the tree along the trunk to make trouble.

Third, in winter, the temperature is very low at night; During the day, due to sunlight, the temperature rises, the trunk is dark brown, which is easy to absorb heat, and the temperature of the trunk also rises rapidly. This makes the trunk easy to freeze and crack. Especially for big trees, the trunk is thick, the color is dark, the tissue toughness is poor, and it is easier to crack. After limewater is applied, because lime is white, it can reflect 40%-70% of sunlight, so the temperature of the trunk has little difference between day and night, and it is not easy to crack.

In agriculture, lime is often mixed with other things and used as an insecticide. The famous pesticide Bordeaux mixture is made of lime and copper sulfate. The main chemical component of Bordeaux mixture is basic copper sulfate, which is a pesticide with strong bactericidal ability.