The color of the needles is influenced by many factors, from natural processes to damage by diseases or pests. If the thuja has turned yellow after winter, you need to figure out the reasons and try to pay due attention to the plant. Let's consider everything in order.
Why did thuja turn yellow after winter and what to do about it
Natural renewal of needles
In evergreen thujas, once every 3-6 years (the interval depends on the variety), a natural change of needles occurs.
At the same time, at the very beginning of spring, the needles lose their elasticity and change color, and subsequently dry and begin to completely fall off, giving way to new ones.
A planned update can be distinguished from negative changes by a number of signs:
- yellowness appears gradually, in the direction from the inner part (trunk and skeletal branches) to the middle and outer surface of the crown, up to the tips;
- the process is subtle and not extensive.
Most varieties of conifers are subject to natural color change, the needles of which become golden, red-copper, bronze or brown.
An exception is the Smaragd variety: it remains green even when grown in the harsh climate of the northern regions.
With the natural yellowing of the tree, no measures are taken. When warmth comes, it will recover.
This process can be accelerated by feeding. It is necessary to fertilize with such mineral complexes, which contain nitrogen.
Sanitary pruning of dry branches and ends helps to save the ephedra from a nondescript look. The goal is to redirect the forces of the plant so that new green needles begin to grow faster.
Landing violations
Spherical or pyramidal thuja can turn yellow immediately after planting, acquiring a brown or golden color in the first spring.
The reason is the violation of the planting technology in the fall.
- The choice of a place close to passing groundwater, which causes rotting of the roots and leads to the drying out of needles and shoots.
- Excessive deepening or, conversely, excessive exposure of the root collar, which leads to the development of stem rot in the part at the base of the trunk.
- Failure to comply with the recommended distance between seedlings, which disrupts the normal growth of branches that do not receive enough sunlight in close contact, in this case the area of contact with a neighboring plant, especially the lower tier, turns yellow.
- Planting in unprepared soil, incl. excessively oversaturated or, conversely, poor in water, excessively dense in structure, without laying drainage.
- The choice of a site in the northern side, poorly lit by the sun, for an ephedra (including indoor) is more suitable for the southeast or southwest direction.
If the thuja began to turn yellow due to a violation of the planting technology, it is necessary to transplant to a new place in compliance with all basic rules: organization of drainage, preparation of a substrate from turf, sand and peat, calculation of the distance between seedlings from 1.0 m or more.
During the procedure, they are examined for the presence of rot, if detected, the damaged areas are removed and treated with Kornevin to accelerate the rooting time and activate the growth of the root system.
Improper care
If the thuja has turned yellow, and its branches after winter have acquired a depressed appearance, the needles have dried up, having lost their density and elasticity, this may indicate inadequate care.
Burns... Most common reason. Covering with non-woven fabric helps to prevent the negative effects of active rays of the sun.
When yellowness appears only on the upper part of the crown inside, there are chances that the tree will regain its original color on its own, without human intervention.
Improper watering. Without added moisture, the plant remains unprepared for the upcoming cold weather, and when the heat comes, it cannot cope with the beginning of the growing season.
Damaged branches must be cut
You can help the ephedra to recover faster if you establish an irrigation regime, additionally cut off damaged shoots and feed them with nitrogen-containing compounds.
The reason for the yellow needles is often insufficient watering in the fall, before shelter for the winter, and in the spring, when the protection is removed.
Poor quality food. The needles turn yellow due to a lack of fertilizers. So, a lack of iron leads to the appearance of yellowness and white spots, nitrogen starvation - to brown, yellow and whitish spots, phosphorus deficiency - to a red-violet shade of needles.
Too tight planting causes insufficient supply of nutrients to neighboring conifers, each of which is trying to pull as much as possible.
Freezing. In the northern regions, it is necessary to create frost protection for the winter.
The shelter helps prevent damage to the bark of the trunk and skeletal branches from frost cracks, and protect the needles from drying out.
Damage by pests
Like other horticultural crops, decorative conifers become the target of pests.
Insects are activated in the spring, when warmth comes, and the risk of injury persists throughout the season.
Aphid
The appearance of aphids is accompanied by a yellowing of the crown, drying out and falling off. Without taking timely measures, the plant dies.
Mole
The primary signs of moth dispersal are the appearance of passages gnawed by the pest in the shoots, the death of the upper tier of the crown.
Spider mite
The defeat of a tick begins with the covering of a thuja with a small cobweb, after which the needles from the inside and outside, at the ends, turn yellow, dry and fall off.
Basic methods of struggle
The main measures for pest control are insecticide treatments, including Actellik, Commander, and others.
Disease affection
It is possible to detect the primary signs of fungal diseases immediately after winter, when the snow melts.
The fungus causes a change in the color of the needles, leading to the drying of the shoots. Common diseases include rust, late blight, shute.
If the crown has turned yellow sharply, the needles die off in a large area, and not only in the area of the apex, it is worth starting treatment as soon as possible in order to save the tree.
Treatment methods
They are treated with antifungal drugs of a fungicidal spectrum of action - Fundazol, Hom, Topsin, by spraying with aqueous solutions.
When late blight is detected, the chances of curing thuja are minimal. The diseased tree is uprooted.
Additionally, dried ephedra is sprayed daily (at the stage of treatment) and once every 7 days (with further prevention) with Epin, which increases resistance to disease.
Why does thuja dry in spring? What to do in this case?
Why does thuja turn yellow and dry
How to recover after winter. Thuya Smaragd. Thuya Brabant.
Preventive measures
In order to avoid the appearance of fungal diseases, preventive measures are effective by spraying the crown with preparations containing copper. Such means include Bordeaux liquid.
Treatments are carried out in early spring, and in unfavorable regions, the procedure is repeated in summer.
Sprayed:
- cracks, frost holes and other mechanical damage on the bark that appeared during the winter;
- branch cuts formed after sanitary pruning.
Massively damaged specimens are removed, followed by uprooting and burning the stumps. The place of growth of the infected conifers is watered with Bordeaux liquid.
In order to prevent phytophthora, which does not respond to treatment, watering the near-stem circle with a solution of foundationol with a concentration of 0.2% is carried out. Additionally, it is recommended to process foliage.