For landscape design, arborvitae are often used. Beautiful evergreens can transform the site and delight with their appearance for many years. Tui are resistant to many diseases and pests, but, unfortunately, troubles happen to them. For example, they may turn yellow.
There are many reasons why yellowness appears, however, this condition of the tree does not always require treatment. First of all, you should know that in some cases you should not worry, since unpleasant phenomena are caused by natural processes.
Sometimes inexperienced gardeners acquire seedlings of varieties for which yellow shades of needles are the norm. This shade can be red, golden, bronze, lemon is found. This applies to the varieties "Golden Globe", "Sankist", "Miriam", "Yellow Ribbon", "Ellwanger Golden". It is advisable to use them along with green varieties to create accents in the garden or park ensembles.
The needles are updated periodically. Depending on the variety, it can occur every 3-5 years, and even every year. Sprigs grow old and die off, the needles dry up and fall off. But in its place a new one will grow. In this situation, you just need to remove the dead elements ..
This should be done manually, without using sharp tools, so as not to damage the tree. In the fall, when the plant is preparing for the cold, cleaning is not necessary. The best time to manipulate is spring
In addition, in some varieties, the color of the needles changes before the onset of cold weather. Although thuja is a frost-resistant plant, surviving even in very harsh conditions, its crown still turns yellow, sometimes it becomes brown. This is characteristic of folded thuja or western thuja. With the onset of heat and the resumption of sap flow, the green color will restore. The return of the attractive appearance will happen on its own, you just need to help the tree with light sanitary pruning. However, there are varieties that do not change color all year round. For example, Smaragd will be distinguished by emerald greenery even in the most unfavorable winter weather conditions.
Quite often it happens that thuja turned yellow after winter. This is often due to sunburn. The bright spring sun, whose rays reflect the snow, is very intense. A plant weakened over a long winter suffers from a lack of nutrients, its protective reserves are depleted, and the tree gets burned. But in this case, the restoration will occur rather quickly, with proper care.
Negative phenomena are caused by improper landing, choosing the wrong place. Beginning gardeners often do not have enough experience to observe all the necessary conditions, as a result, the thuja dries, and in the first year it may completely turn yellow. There are several factors that provoke the problem.
- Groundwater is very close to the surface. The root system rots, and, as a result, the branches dry out.
- Unsuitable soil. It should be neither clay nor sand. In the first, moisture stagnates, in the second there is not enough moisture. And also the presence of a large amount of peat is not suitable.
- The root neck was too deep or bare during planting. The growth of the tree is inhibited; stem rot may appear.
- Thickened landing. Thuja growing up interfere with each other, their root systems become crowded. The branches are in close contact, the air circulation is disturbed, which causes a whitewash, yellowing and discharge of needles.
- The abundance of sunlight. Thuja planted in an open area will inevitably turn yellow if the number of clear days is large. In addition, in open space, the negative effect will be amplified by drafts that the thuja does not tolerate.
Errors in care may also lead to yellowness.
- Excessive or insufficient watering. If the plant does not have enough moisture, especially in the dry period, then the ends of the needles will acquire a brown hue.
- Not enough fertilizer applied. Iron deficiency will affect the condition of individual sites and young shoots: they will lose pigmentation and become pale. If there is not enough phosphorus, then a reddish-purple hue will appear. However, an excessive amount of fertilizer will have a bad effect on the decorative qualities of thuja.
Unfortunately, diseases can affect tuyu. In early spring, when snow melts, in some cases traces of parasitic fungi and mold are found. If you do not start treatment in time, they will spread and cause not only a changed color of the needles, but also the death of young plants. And also the tree can suffer from the invasion of insect pests.
It happens that in a healthy and well-groomed plant the lower part of the crown suddenly turns yellow. See if your pets are the culprits: dogs and cats. Their marks can cause a similar effect.
Another factor contributing to the appearance of yellowness may be the proximity of large highways and busy streets, where reagents are used to quickly melt snow. Despite the persistence of thuja, meltwater, containing reagents and aggressive substances from car exhaust, sometimes affects the root system.
How to treat?
If you find subtle yellowing from the inside of the trunk, then this is obviously the usual process of dying off old needles. When yellowing is massive, then you need to urgently look for the cause and conduct adequate treatment. If the thuja has suffered from sunburn even in the presence of shelter, then with the onset of heat and the disappearance of snow, dried branches must be removed and the trees plentifully watered. It will not be superfluous to spray them with growth stimulants. Suitable "Epin" or "Zircon", designed for coniferous species.
For thickened plantings, any specific treatment is not required. The situation is saved by planting carried out on time. For their full-fledged growth and development, it is necessary that the distance to the nearest “neighbor” is about 1 m.
Errors discovered during planting and site selection are corrected by establishing drainage, adding the necessary elements to the soil (sand or peat), mulching. A good solution would be to choose a more suitable location for a transplant. And you should also ensure proper care: regularly water and feed.
If during spring inspection fungal and mold lesions are found, treatment should be started immediately. First of all, you need to carry out sanitary pruning, carefully removing all infected branches, and destroy them. The cut sites are disinfected with copper sulfate (5% solution), and then a fungicide with a wide range of effects is used. Well established "Fitosporin", "Skor", "Keeper". Dosage and administration are indicated on the package. However, if the plant is infected with late blight, treatment may be useless. The tree must be dug up and burned.
The invasion of insects greatly reduces the defenses of the thuja, it may turn yellow and die. In this case, it is necessary to treat the plant from yellowness by special means. Their choice depends on the type of pests. For example, aphids can be eliminated using a soap solution. It is used once a week until the complete disappearance of insects.
One of the most common pests of thuja is a false shield. From a small number of individuals, the plant is quite possible to mechanically release. With large quantities, you can fight using "Aktaru" or "Aktellik". The procedure is carried out 2-3 times, the interval is 10 days. In addition to spring, summer processing is carried out to prevent the development of new larvae.
After getting rid of insects, it is required to restore the health of the thuja with the help of mineral top dressing.
To avoid many problems and mistakes during care and planting, during the acquisition of seedlings, you need to carefully familiarize yourself with their varietal features. Each variety has its own characteristics related to frost resistance, shape, favorable growth conditions, and resistance to diseases. And if in some species a change in the color of the needles is a normal natural phenomenon, in others it is an occasion to take urgent measures to save the trees.
It is advisable to purchase seed in specialized nurseries: so you will be sure that you get healthy seedlings, and employees will be able to give competent advice. Be sure to follow all the recommended measures for choosing a site, follow the rules of planting and care. For timely identification of landing problems should be regularly inspected.
An important measure to prevent the appearance of yellowness in the spring is the organization of proper wintering. In early autumn, you should stop feeding, continue watering. To protect the roots, by the beginning of winter, fallen leaves and bark are laid around the trunk with a layer of 10-15 cm. In young thuja, branches are pressed to the trunk and tied. The trees are wrapped using non-woven material.
If the tree is older than 3 years, you can not wrap it. But so that the branches do not break under the weight of the snow or in a strong wind, they are connected. And also during the winter you need to shake the snow from time to time.
To protect thuja from sunburn, additional protection should be organized. For this purpose, until complete thawing occurs, the coniferous plant must be covered with any material: camouflage net, burlap, lutrasil, kraft paper. You can even use a regular sheet. Sometimes it’s enough to protect the tree only from the sunny side. It is not necessary to wrap too tightly to provide air access.
To prevent the appearance and spread of fungal infections in the spring, fungicide plantings need to be sprayed. Bordeaux liquid or other preparations containing copper are suitable. In clay areas where moisture can accumulate, the procedure should be repeated in the summer.
Coniferous species are characterized by such a fungal infection as brown shute. Most often, young plants suffer from it. The disease is detected after snow melts. It is manifested by the appearance of yellow spots on the needles. Soon, a yellow-brown color will appear at the needles, it will be replaced by a bloom of gray-black color. To prevent this, in the spring, thaw from yellowing is saved with the help of Fitosporin.
In addition, in the spring, thuja should be treated with insecticides from yellowing caused by pests. Their appearance is possible to prevent. The earth around the trunk must be periodically carefully loosened, weeds removed and, if necessary, treated from insects.
About why the thuja turns yellow and how to save it, see the next video.