Why thuja needles turn yellow: experts named six reasons - and one very unexpected one
When this happens, there seems to be no adequate reason why. However, experts say that there are as many as six reasons why thuja needles turn yellow. This was reported by SSPDaily.
Seasonal color change
Certain varieties of thuja change their color depending on the season. For example, the western thuja and the folded thuja can turn yellow in the fall and winter. Such varieties as Holstrup, Columna, and Brabant also change color. But their needles turn brown. So before you panic, make sure you don't have one of these varieties.
Mistakes during care
First of all, thuja can turn yellow due to an incorrectly chosen planting site. If you plant the tree at a great depth, it will develop at first, but after six months the needles will gradually begin to turn yellow. A similar story happens if the neck of the tree is too exposed. Take into account the properties and wishes of each individual variety when planting.
A lack of nutrients can also cause yellowing. Often, thuja is planted on a site and forgotten about. But if the tree lacks minerals and other components, it begins to turn yellow. Fertilizing is done once a season.
Thuja also likes moist soil, and when it dries out too much in summer, the needles can turn yellow. Be sure to water the tree on dry days.
Sunburn
One of the main reasons why thuja turns yellow. It is in spring that the tree receives the most severe burns, because in May the sun can already shine quite brightly. A similar story can happen even in winter. Although the air temperature is low, the sun's rays are still active and can leave their mark on the tree.
It is difficult to protect yourself from sunburn. But you shouldn't worry too much, because thuja always regains its color. However, you will have to increase watering and fertilize to recover.
Pests
The main pests of thuja are:
- weevils - they attack almost all plants and trees;
- mites - these pests can be seen only during a thorough inspection;
- caterpillars - although the damage is insignificant, it is worth fighting;
- aphids - rarely attack, but can be found on needles;
- larvae of the deciduous leaf beetle - they can "kill" a tree in a few months.
To avoid the effects of pests, you need to spray the thuja once a season for prevention purposes.
Diseases
Although thuja is considered a fairly resistant plant, it can also be attacked by certain diseases, in particular fungal diseases. The only option for protection is preventive treatment of the branches. Most often, thuja becomes infected from other trees or shrubs. If you notice that the fungus is already developing, you will have to use more powerful drugs.
The influence of animals
Although this is a rather unexpected reason, thuja can turn yellow because of animals. If there are cats or dogs on the property, they can get into the habit of going to the bathroom under the tree. At first, the needles will turn yellow and the bark will turn black. And then the damage can be quite serious.