When a thuja turns black, there can only be two reasons for this:
1 Exposure of needles to animal feces, both cats and dogs.
2 Fungal diseases
The photo on the left shows the result of exposure to animal feces, as the contact zone is clearly visible. In differentiating the two named causes of blackening of the thuja, it is important to experimentally observe the duration and progression of the process, the presence of visible fungal spores or fungal plaque, and the presence of neighboring areas of damage to the needles of different nature, the presence of animals in your or a neighboring yard (believe me, you will not see when they mark your favorite thuja). It also happens that the blackening of the thuja is associated with both of the above reasons.
Thuja has turned black - what to do. Before the exact reasons for the blackening of the needles are clarified, time may pass, during which the condition of the thuja may worsen. Therefore, in any case, spray the thuja once or twice with fungicides against fungal diseases, as this will not harm the plant if you have not done this procedure for a long time.
The first reason is from animal feces Thuja leaves turn black where the needles come into contact with urine (see photo). The extent of blackening depends on the duration of exposure to the damaging factor. If you look at individual branches, the areas of blackening on them at first are scattered, that is, they are located in a chaotic order, like splashes of watercolor paint (see photo under the next paragraph). Unlike, for example, fungal diseases, in which the infection spreads gradually along the shoot. As urine is exposed, the thuja develops a large area pronounced blackening as if painted over with black paint. These areas will not be restored in the future. In the photo below you can see typical example, which raises no doubt that the thuja has turned black from animal excrement (photo clickable).
The affected thujas, which we see in the top photos, are close to death due to the extensive area of the lesion. In general, the area of affected areas largely depends on the height of the animals that “mark” the plant and on their number in the yard. Moreover, the urine of not only dogs, but also cats, as well as all other animals, is destructive for thuja. Below, see my photos of some twigs and plants, how the needles of a thuja turn black from animal feces (the reason was correctly established with the personal presence of a professional):
In the photo, individual needles have turned black at the points of contact. What then happens to them? They begin to gradually dry out, lose their shine, then die and crumble. If you have a short thuja and a large dog in the yard “looked” at it, then the plant will inevitably die if you do not take action. Unfortunately, the needles damaged by feces will not recover and such areas on the thuja will remain “bald” in the future. It happens when animals begin to mark a tall thuja from below, so only its lower parts suffer.
What to do if the thuja turns black from animal feces. To begin with, you can try to wash off the remaining feces with plain water. In any case, this will not harm the thuja. Then you need to create a fence that would prevent dogs and cats from marking the plant. You can also use repellent aerosols, which are sold in veterinary pharmacies. Of the natural repellents, I can only recommend ground pepper, the smell of which is not liked by either dogs or cats. You should first try to comb out the blackened needles with your hands, because if the branch is alive, it is possible that some of the needles may be restored. For this purpose, it will not be superfluous to use resuscitating solutions. For example, to stimulate the growth of new shoots, the crown of the thuja needs to be sprayed with growth stimulants, such as Zircon, Epin, etc. These preparations can be sprayed 2 - 3 times with an interval of 1 - 2 weeks. Completely dried branches will have to be cut off.
The second reason for the blackening of thuja - from fungal diseases. It should be noted that the vital activity of microorganisms such as fungi is associated not only with different changes in the color of thuja needles, but also with the characteristic appearance of fungal sporulation on its surface. Fungi are perhaps the most common problem for gardeners, causing various manifestations of disease in plants.
Of course, fungal diseases do not immediately cause blackening of needles, and not all of them lead to this result. There are many causative agents of fungal diseases, but they also have something in common. For example, the needles first turn red-brown, brown or red, and then may darken. Upon closer examination of the affected areas, you can see fungal spores in the form of black dots or streaks. There are fungi that cause needles to rot and also cause early spring dense mycelial films or plaque from white, white-gray to dark brown. The presence of the thickest and darkest plaque in the spring is characteristic of a fairly common disease of conifers, called brown chute. It was during this period that the presence of a dark coating makes us wonder why the thuja turned black after winter (see photo). In summer, when infected with brown schutte, you can see the black fruiting bodies of the fungus.
In the first photo on the left, yellowed areas of the needles are visible, and inside there are areas of blackening, which, due to the nature of their localization, cannot be the result of exposure to animal feces. Apparently this is a fungal disease. In the second photo from above, areas of blackening are adjacent to areas of browning and yellowing of varying degrees of severity, allowing us to make a preliminary conclusion that the blackening was the result of the aggravation of a single progressive process, more likely, fungal disease.
With brown chute, the needles of the thuja first turn yellow, then, as the disease develops, they acquire a darker and even black-brown color. In mid-summer, the fruiting bodies of the fungus that causes this disease are visible to the eye, they are oval in shape and black in color.
In any case, only a professional can distinguish fungal diseases, but it is enough for us to know only them general signs and be able to treat the plant. More details about thuja diseases are written in another article: what does thuja suffer from and how to treat it.
Treatment of fungal diseases. The needles are sprayed with any of the known fungicides: foundationazole, copper oxycholoride, Hom, etc. Usually spraying is carried out twice, sometimes three times (depending on) with an interval of 1 - 2 weeks. It should be remembered that excess copper leads to slower growth. Then the yellowed needles from living branches are raked out by hand, followed by spraying with a growth stimulant, since new leaves may appear on them, although this is not a fact. As a stimulant, you can use Zircon in a concentration of 4 drops per 1 liter; you can spray it several times at intervals of a week. If the plant is weakened, then the crown can also be sprayed with Epin mixed with Cytovit 3 times with an interval of 1-2 weeks. Completely dried diseased branches should be removed and burned, the same should be done with dead plants, since they are a source of infection.
Along with services for pruning thujas, cutting thujas and scheduled annual maintenance, we at Garden Academy Moscow treat thujas against pests. For example, if your thujas turn yellow outside or inside, turn brown, turn black, or have manifestations of other thuja diseases or thuja pests, or if you decide in advance to protect yourself from the manifestation of diseases in thujas by protective treatment tui - call us. Our specialists will find out the causes of diseases, draw up a treatment plan and solve this problem. Usually one, two or three treatments are required at intervals of 7 days.
Why do thujas turn yellow and what to do?
There are many reasons for the yellowing of thuja needles. This may be due to various fungal infections, as well as other reasons completely unrelated to diseases. For example, in winter a burn can occur from cold, and in spring from sun.
Pests of thuja and other causes of yellowing of thuja will be discussed in this article. We will look at how to prevent yellowing of thuja needles and how to deal with pests.
Why do thuja needles turn yellow? What ails thuja. About pests of thuja.
Yellowing of thuja is not associated with diseases and pests. It should be remembered that during the winter, thuja produces a special protective red pigment in its needles, which changes the color of the plant from slightly brownish to intensely brown and even pinkish-bronze (depending on the type and variety of thuja).
Yellowing of the top of the thuja indicates that it is not getting enough nutrients due to damage to the root system. This may be due to two reasons. The first reason is an excess of moisture at the level of the root system. This happens in conditions of stagnant water or high level groundwater. The second reason is damage to the roots by fungal diseases (read on the page: thuja diseases).
Observational experience shows that most often thujas turn yellow due to excess moisture in the soil. For example, it is dangerous to plant thuja in low places where water often stands and accumulates there after melting snow or heavy rainfall. If you know in advance that the soil is prone to waterlogging and stagnation of moisture, you need to either immediately choose another place for planting, or do it in such soil in advance. good drainage for water drainage. In conditions of waterlogging, the needles of the thuja turn yellow, as the roots become soaked and rot. The rotting process spreads to the bases of the skeletal branches and the plant inevitably dies.
If the thuja begins to turn yellow in waterlogged conditions, it is better to immediately transplant it to another place. According to one of the experts, thuja Smaragd is capable of withstanding spring stagnation of moisture in a layer of water of about 10 cm for a week. However, under such conditions, about 5 - 10% of thuja Smaragd die. However, surviving plants still suffer in the future and are characterized by slow growth. Root soaking is often accompanied by a fungal soil infection that causes fusarium or root rot. As a preventative measure on stagnant soils, site drainage is used or selected right place for landing. Diseased plants are replanted and treated Bordeaux mixture or special drugs with a similar effect. In professional nurseries, spraying with a 0.2% solution of foundationazole is used against root rot.
The next reason for the yellowing of needles is their damping off. We are talking about damping off of needles in cases where thuja needles turn yellow and die due to poor air permeability and lack of light in places where closely growing plants come into contact with each other or with a massive fence (solid wall or fence). In some cases, damping off of pine needles is also associated with removing the winter shelter too late. When covered with lutrasil, the thuja will also rot. The needles in such places turn yellow, dry out and easily fall off. As preventive measures, it is recommended to plant plants on time, observe the correct interval when planting them in advance, and monitor the condition of covered plants as spring warms.
You should not plant thuja too close to cast supports, walls or fences that do not have free spaces and thus create continuous shadow and drafts. The crowns of plants on the side of such supports turn yellow from exposure to winter drafts and lack of light.
Often we are faced with the fact that the thuja turns yellow inside, only around the trunk. The outside color of the shoots is normal. The yellowing of these areas is associated with insufficient light supply to them, as well as with the limited life cycle of the needles (they live up to 3 - 5 years). The yellowing of the thuja on the inside has virtually no effect on its appearance, since on the outside this defect is hidden by densely located healthy shoots. The process of yellowing of the thuja inside is natural and is not associated with any diseases.
We can often observe that our thuja has turned yellow under the rays of the spring sun. Then we can talk about sunburn of pine needles. Burns on thuja are observed in early spring, with the beginning of the growing season, when the plant has already woken up and started to grow, but the developing needles have not received enough moisture due to the fact that frosts are still present and the ground has not had time to thaw. To prevent spring burns, it is recommended to shade species that are sensitive to them in the fall, especially on the south side, and also to do good watering before winter so that the needles absorb enough moisture. In addition to the above, it should be noted that different types Arborvitae are susceptible to sunburn to varying degrees. The most resistant in this regard is the western thuja, and the least resistant is the eastern thuja. If burns have already appeared, it would be a good idea to apply shading before the ground thaws. You can also water with warm water and spray the needles in the absence sun rays. Spraying with zircon gives a good effect.
Increasing the dose of fertilizer recommended by the manufacturer leads to oversaturation of the plant with microelements and also causes yellowing of thuja needles and root burns. Don't overdo it with fertilizing! Use only special fertilizers for conifers. When planting thuja in spring,
Insufficient iron content in the soil also leads to yellowing, sometimes whitening, of thuja needles on various independent shoots. Similarly, the red-violet color of the needles can signal a lack of phosphorus in the soil, and chlorotic needles and slow growth of thuja can indicate a lack of nitrogen in the soil.
Frost damage and winter drafts can also lead to damage to thuja branches and yellowing of the needles. Frost cracks are cracks in the bark that appear on the branches or trunk during simultaneous exposure to frost and sun. Depending on the location and depth of the lesion, the needles of the thuja may turn yellow or may remain green. Frost cracks are treated with 3% solution copper sulfate, then covered with wood balsam and garden varnish. Winter drafts lead to frostbite of parts of the plant, damaged branches turn yellow and die. Plants growing near solid walls or fences are susceptible to winter drafts.
If your thuja grows along the road and in winter the tips of its needles turn yellow or brown, and this mainly happened on the lower parts of the plant, then it is reasonable to assume that it was affected by special mixtures that road workers sprinkle during this period in order to eliminate ice.
Mechanical damage to branches can be caused by the weight of snow or ice adhering to them, when branches bent to the ground not only deform the crown, but also break. Happens, big trees They lose entire branches. This happens after heavy precipitation in the form of sleet or freezing rain. Adhered snow must be carefully shaken off with a long wooden stick. Broken and broken thuja branches will turn yellow.
The next reason why thuja needles turn yellow is a lack of moisture in the soil. During a long dry period, all thujas need watering. Young and recently planted plants are especially sensitive to soil drying out. First, the thuja fades due to loss of moisture, and then begins to turn yellow and dry (read below).
If the thujas turn yellow after planting.
1. Insufficient watering. Thuja at any age loves moderately moist soils and does not tolerate excess water. Ideally, the soil for it should always be moderately moist. This way the thuja develops better and grows faster. However, according to experts, thujas require mandatory watering after transplantation, during prolonged drought and at a young age. This suggests that young and recently transplanted plants have a lower drought tolerance threshold. As a matter of fact, that’s how it is. By the way, successfully established plants after spring planting, may not survive a dry summer and require closer attention. It is enough to assess the soil moisture status by touch and prevent it from overdrying.
2. Violation of planting technology. If there is insufficient depth, the roots will suffer from drought and this can cause not only yellowing of the thuja, but also the death of the plant. During the planting procedure, the plant needs abundant watering. Not only the planting hole is generously filled, but containers with plants are spilled through. The lump of earth is also watered until it is moist and does not fall apart. Some sources write that excessive deepening can lead to yellowing of the lower branches of the thuja, poor growth or plant freezing and even root rotting. Such problems do not always occur, but the situation can be corrected by freeing the root collar in a circle from the excess layer of soil.
3. Broken branches during transportation. Damaged thuja branches will soon turn yellow and will have to be removed. The thinned areas of the crown will overgrow on their own over time, but they can also be covered with neighboring branches, securing them with wire in the desired direction. To prevent such damage, plants must be properly positioned in vehicle. Also, the crown of the plant can be tied before transportation, although for many varieties of thuja this is not mandatory and depends on a number of factors.
4. Waiting too long for planting from the moment the thuja is dug out of the ground. During such a pause, in the absence of watering, the roots may dry out. When the roots dry out, the result will not be long in coming: planted after a long water-free pause, your thuja will turn yellow partially or completely. The plant may not die, but it will be much more difficult for it to take root. There is only one conclusion: the lump of earth should not dry out before planting, therefore it requires watering and proper storage. If the branches are still alive and only the needles are damaged, remove the yellowed needles with your hands. Such branches may eventually become covered with new shoots.
The thuja has turned yellow from pests.
Pests of thuja. The activity of thuja pests greatly weakens the plants and often causes their death. Pests of thuja are thuja aphids, which are bred by ants, spider mite, gray larch leaf roller, moth, click beetles, bark beetles, thuja false scale, thuja pine beetle (trunk pest).
The thuja aphid is gray-brown in color and covered with a silvery coating. Upon closer inspection, this aphid on thuja can be seen on the underside of the shoots. Aphids are plant sap-sucking insects that live in numerous colonies, so over time their activity causes the needles to turn yellow and fall off.
You can treat thuja against pests using a soap solution. Treatment with this solution is repeated at least twice - three times every 7 - 10 days. If aphids are too numerous, insecticides should be used to control them. Be sure to destroy the anthills on the site, as the ants are busy colonizing aphids.
Moth larvae - moths - gnaw through the tissue of the tips of thuja shoots, making passages in them. Upon careful examination, you can see entrance and exit holes, as well as tiny caterpillars, on the affected parts of the plant. The butterfly itself is also very small (up to 4 mm) and flies out at the end of May. The moth - moth - is a mining moth; it lays its eggs in the apical shoots of the thuja, from which larvae emerge again in the spring. So annual life cycle the pest is repeated again. The thuja needles turn yellow and die.
If butterflies or larvae are detected, they must be mechanically removed and the plant parts damaged by them. Chemical insecticides are also used to control insects. To prevent the spread of the pest, in July, two treatments should be carried out with special products containing pyrethroids. The interval between treatments should be 8 days.
The gray larch leaf roller is a small, dark caterpillar. Affected shoots are characteristically entwined with cobwebs. In some places, a cobweb connects the needles into a cocoon; inside each cocoon there is a caterpillar. Caterpillars emerge from eggs and after 3 - 4 weeks turn into pupae and then into butterflies. The wingspan of the butterfly is 20 - 22 mm. Pine, spruce, and larch are most often affected. If there are a large number of insects, the plant may die.
For prevention, plants are sprayed with insecticides in May - early June. If there were too many caterpillars, re-treat in the summer.
Beetles are click beetles, or rather their larvae are root pests found in the ground. By eating the roots, they cause general weakness in the thuja, stunting of growth, then the thuja turns yellow and dies. The larvae of click beetles are popularly called wireworms. Having grown from larvae, the click beetle differs from others in its ability to turn over from its back to its legs, making a characteristic sound when jumping. The larvae develop in the ground for 3 - 5 years, grow up to 2.5 cm and, as they mature, begin to eat the thicker parts of the roots.
To destroy the larvae, the ground is watered with products containing diazinon. The appearance of click beetle larvae is facilitated by soil acidification and waterlogging, so these factors should be eliminated. It is useful to carry out preventive digging of the soil in the fall.
Spider mites can be easily differentiated from other pests by the presence of a thin web covering, which over time covers a large area of the crown. This pest is most often found on Canadian spruce trees. Insecticides help in the fight against spider mites.
Bark beetle - very dangerous pest plants, affecting not only thujas. The pests themselves and their larvae eat the wood, gnawing many holes in it. Plants affected by bark beetles die within a month. The size of the bark beetle is 0.8 - 9 mm and it has many varieties.
When a thuja beetle appears, the plant must be treated with special insecticides. If they are of little use, it is better to destroy the plant by burning it. This pest is somewhat similar in appearance to a bark beetle and makes small holes in the trunk. Sometimes you can see curved passages in the bark and small wood shavings fall off the tree.
If your thuja has been affected by a false scale insect, then when examining the shoots of the plant you will find rounded dark or light brown growths on them, very similar to buds. These are adult pests and their larvae. Adult pseudoscale insects spend the winter in the litter, and their larvae overwinter in the bark of young shoots. The size of the false shield is about 3 mm. Thuja does not die immediately, but it always significantly weakens its growth, and its needles at first look dull and lethargic, then turn yellow and dry out.
How to treat and prevent. To prevent infection, in early spring, as soon as the ground has thawed, special caterpillar glue is applied to the base of the trunks, blocking the insects’ path to the top. For the same purpose, you can wrap burlap around the trunks, since it acts as a trap. If there are few insects, it is enough to clear the shoots from them by any mechanical means. In case of extensive infestation, insect pests are destroyed with insecticides. Aktara solution gives a good result, which needs to be treated twice with an interval of 10 days. You can use Actellik according to the same scheme. Treatment must be repeated in the summer (in mid-July and August) to prevent the development of a new generation of larvae. There is no need to list all the names of insecticides, since in any garden center They will help you choose the right one.
Now the thuja requires resuscitation measures to restore its health - this mineral supplements, regular watering, as well as spraying and watering with growth regulators (zircon, epin give good results).
*The exact price is determined by photo or video. *Note - the cost of pruning thujas depends on the height and depth of the crown (width), on the diameters of the trunks and on the number of trimming edges that the client orders.
Specialists in this service
My husband and I planted a beautiful thuja as a hedge in our summer cottage. We thought that there would be no worries with her - I planted her and that was it. But winter passed and we noticed that this evergreen thuja suddenly turned yellow, and in some places even turned brown! Not immediately, but we were able to not only identify the cause of the disease, but also cure our thuja.
Now she again pleases us with her healthy and well-groomed appearance! In this article I want to tell you what can make a thuja sick after winter, how to cure it, and how to protect it from diseases and pests in the future. Then your thuja will be all year round delight with its evergreen beauty!
First you need to find out whether annual yellowing is normal for your thuja variety. There is a variety of thuja whose needles darken before the onset of the winter season, thus preparing for winter in order to more easily endure the cold. With the onset of spring, it returns to its green color again.
If you notice that the thuja periodically turns yellow at the bottom of the crown, then do not be alarmed, this is a natural process for it. In this case, it will be enough to remove the yellow processes.
If you frequently water a thuja that has recently been planted, and also move the pot with it around summer cottage or place it under the scorching rays of the sun, it will turn yellow very soon.
Pets can also damage it by digging into its roots or gnawing on its needles. Therefore, it is not advisable to allow animals near the young thuja.
Spring sun rays
One of the main reasons for the yellowing of thuja needles may be the spring sun, whose rays are reflected from the snow that has not yet melted, thereby increasing their intensity. It is not surprising that thuja, having just woken up from the winter cold, often gets sunburned in the spring.
It can only be saved with the help of a covering material that will protect it from the sun's rays. You can use any burlap, spruce branches or craft paper as a covering material.
It is advisable to cover it at the end of winter; if there is not enough covering material to cover the entire bush, then the thuja can only be covered with sunny side. But do not close it completely, it must have access to air.
If she has already received a burn, then in this case she needs to be hidden in the shade and watered more often. Over time, it will definitely grow needles and return its original green color.
Fungal diseases
Like many plants, conifers are also susceptible to fungal diseases, which can cause their needles to turn yellow and fall off. Therefore, first of all, after planting the thuja in the soil, it needs to be treated with an antifungal solution from the foundation.
Pour ten grams of the drug into a ten-liter bucket of water and mix thoroughly. It is advisable to water the thuya with this solution periodically. But it can be replaced with Bordeaux mixture.
Brown shoots
This is the name of the fungus that causes brown shoots. When a thuja is affected by this fungus, it very quickly turns brown. In this case, it is important to notice the disease in time and immediately remove the infected branches.
Then add fertilizer under the root and sprinkle limestone on top. Then, every two weeks from June to November, the entire crown of the thuja needs to be sprayed with 0.2% Fundazol.
Rust
It often affects young needles that have only recently been planted. The needles acquire dark brown color and everything is covered with red dots. In this case, the affected branches should be cut off and burned. And treat the plant with copper-containing preparations.
To prevent rust from affecting thuja in the future, it is advisable to periodically treat it with this drug. Additional watering under the roots with Fundazol will not hurt.
Late blight
This is the most dangerous fungus that completely destroys a coniferous plant. During this disease, the needles become gray and noticeably wither, and the trunk, which is most affected, becomes soft to the touch and covered with plaque.
If it came from a bush bad smell, then this is a signal that the fungus has already penetrated the roots. In this case, the plant must be pulled out and destroyed. After this, the soil must be thoroughly treated to remove fungal spores so that neighboring plants do not get sick.
Therefore, when planting thuja, there must be drainage at the bottom of the hole, which does not allow moisture to stagnate in the soil. To prevent the thuja from being affected by this fungus, it must be periodically sprayed with Fundazol.
Pests
In addition to fungal diseases, thuja, if not taken care of, can be attacked by insect pests, from which it can die.
In this case, you need to carefully examine the branches and needles of the thuja using a magnifying glass, since the insects are often very small and difficult to notice with the naked eye.
Bark beetle
leaf roller
The presence of a leaf roller on a thuja is evidenced by small cocoons attached to the needles using a web. This very small insect can easily destroy a thuja in a month by feeding on it. To get rid of the leaf roller, you need to treat the affected shrub with insecticides in May, June and July.
False shield
If on the underside of the needles you find yellow-brown small insects, no more than three millimeters in length, then this is a false scale insect, the most dangerous pest that short term can destroy an entire bush.
If there are few of them, then it is simply cleaned off the branches and bark with a brush. And if there are a lot of them, then only spraying with insecticides will help. To prevent the false scale insect from attacking the thuja in early spring, as soon as the snow melts, the trunk is wrapped in burlap.
moth
It is not the moth itself that feeds on thuja, but its larvae, which it lays in the needles. The larvae themselves are very small, not exceeding four millimeters.
Usually she lays eggs in June, so in this month and July the bush must be sprayed with preparations containing pyrethroids so that the moth does not settle on the thuja. But if the thuja has already managed to attack the thuja and damage the top of the bush, then all that remains is to cut it off and treat the rest of the crown with the preparation.
Spider mite
If the needles are entangled in a web, and small red insects are running along the branches and needles, it means that it was attacked by a spider mite, an incredibly prolific pest that is difficult to get rid of.
It appears on plants suffering from drought in the hot summer and sucks out the last juices from them.
Therefore, to prevent spider mites from visiting the thuja, it must be watered in the hot summer. To get rid of mites, the plant needs to be sprayed with garlic tincture. But if the tick has already managed to reproduce a huge offspring, then only acaricides will help.
Wireworm
If you notice that the thuja began to get sick often and stopped growing, its branches began to dry out, look at its roots, there is a high probability that you will see small golden worms there. This is a wireworm that harms the roots of the bush, destroying its immunity.
To get rid of wireworms, in late autumn you need to dig up the soil around the plant, drain and deoxidize the soil. If there are a lot of wireworms, then the soil is mixed with products containing diazinon.
Aphid
If numerous small gray-brown insects are found on the shoots, then these are aphids, which like to feed on the sap of the tree, causing it to dry out.
If there are not very many aphids, then you can get rid of them by washing the needles with soap. This should be done weekly, covering the soil with waterproof film so that soap solution did not penetrate into the roots.
If there are so many pests that even washing does not help, then spraying the bush with any insecticides will help get rid of them.
To prevent any insect pests from wanting to settle on your thuja, at the end of spring, as soon as the snow melts, it is advisable to spray the conifers with Fufanon.
Spraying should be repeated twice a month until late autumn. In hot summers it is better to spray early in the morning or late in the evening. And do not forget to wear a protective suit and cover your face with a protective mask when spraying.
Planting and care
Many novice gardeners make the same mistake when planting thuja, placing its root collar too deep in the ground or leaving it on fresh air. Or they even completely forget about the drainage at the bottom of the pit. Because of this, immunity decreases coniferous bush, and its roots are affected by rot.
It is also undesirable to plant thuja next to groundwater, since its roots will rot, this will lead to the branches drying out and dying. Thuja is not a moisture-loving plant.
It is not recommended to plant thuja too close to each other, as they will touch branches and feel crowded, and therefore can stop their own growth and throw off their needles. The distance between them should be at least a meter.
The soil for planting should not be too dense, acidic, wet, or poor in minerals. The soil should consist of turf land with the addition of peat.
If the above mistakes were made, then it is better to transplant the coniferous plant into a more good place and don't forget about drainage. The first time after transplantation, it is better to protect it from the scorching sun to allow the plant to calmly adapt to the new place.
And you definitely need to mulch the ground around it with sawdust or peat. Water once a week for the first month, and then less often.
Thujas look very impressive in landscape design, but they need to be properly cared for. Very often gardeners are faced with a problem; they ask the question: the thuja has turned yellow after winter, what should I do? Let's figure out what could be the reasons for the yellowing of the thuja crown, and how you can cope with this scourge.
Sometimes the thuja turns yellow inside. If you move the branches of the needles apart, you can see this yellowing. We can say that this is the norm, since the needles change every season. Old branches that are located inside the crown are aging. You should not touch dried branches before winter, and in the spring you need to manually clear the thuja from such branches. It is better not to use a tool, otherwise you may damage the plant. And any microtrauma will lead to infection.
In autumn, some types of thuja can change the color of the plant crown to yellow-green, and sometimes brown-green. Therefore, if your thuja has changed color, do not immediately panic. You may have Thuja cuspidum or Thuja occidentalis growing in your garden. In the spring, when the snow melts, the soil thaws, and sap flow begins in the trunk and branches of the tree, the needles will turn green again. Many coniferous trees prefer to change color, it's kind of defensive reaction trees from the spring sun. For pine needles, burns received in the spring can be disastrous.
Can lead to yellowing of needles severe frosts. If the winter has little snow and frosts reach 30 degrees, cracks form on the trunks, and the needles on this side turn yellow. It is difficult to insure against this. In regions with harsh winters, it is better to cover thuja every year, and not just in the first year.
Other causes of yellowing of the crown
Thuja needles may turn yellow for the following reasons:
- Excess or lack of fertilizers.
- Sunburn in spring. Young thuja is very sensitive to the sun and changes in weather.
- There is a lot or little moisture in the soil. At large quantities moisture, the top of the thuja turns yellow.
- Diseases and pests. Yellowing can be caused by false scale insects, as well as Fusarium disease.
Reasons for blackening of thuja after winter
After frosts, sometimes dark, almost black spots can be found on the thuja. There are two reasons for the problem:
- This may be due to a fungal infection. If the spots are few and small, you can limit yourself to treating the fungicide. It is carried out twice, taking a break of two weeks. Areas that the fungus has managed to infect must be removed. If a large part of the thuja is affected, the tree should be removed, otherwise it will infect the rest of the plantings.
- If the black spots are concentrated on the lower level of the tree, pets defecating on the arborvitae are most likely to blame. If large areas of the tree are affected, the thuja will die and must be removed.
How to make thuja look green again
After finding out the reasons for the yellowing of thuja needles, you need to begin resuscitating the plant.
Incorrect landing
Why does thuja turn yellow after planting? Beginning gardeners often make mistakes when planting thuja seedlings. It is necessary not to bury the seedling too deeply; the root collar should remain at soil level. When planting, you need to remember that after a few rains the soil will settle and the tree will sink a little more.
If the thuja suddenly begins to turn yellow, you need to check whether the planting site has been chosen correctly. Perhaps the thuja grows in a damp place, or it is too dry. Drying out, as well as excess moisture, can destroy the plant.
If there is a lack of moisture, you must immediately water the plant, and additionally spray it. If the sun constantly hits the thuja, it needs to be shaded a little. After this you need proper watering, it is recommended to spray with Epin-extra.
What to do if there is stagnant water in the area? Drainage grooves can be dug to allow water to drain away from the planting hole. But this is possible if the slope of the site allows it. If it is not possible to arrange drainage ditches, create raised beds onto which the thujas are transplanted.
Fertilizer shortage
- For the proper development of thuja, you need to maintain a balance of micro and macroelements. Yellowness can be caused by a lack of manganese, copper, potassium or nitrogen. If yellow areas are detected on the needles, it is necessary to analyze all the fertilizers to determine whether all the elements are sufficient in these fertilizers.
- The leaves become pale green, the shoots stop growing, which means that the thuja does not have enough nitrogen. Impaired nitrogen metabolism can cause potassium deficiency. Ammonia accumulates in the crown, which leads to yellowing and further death of the shoots.
- With a lack of copper and iron, the process of photosynthesis is disrupted, and thuja needles lose their green color.
- Leaves may turn yellow due to chlorosis caused by manganese deficiency.
Diseases and pests
Many pests can cause thuja shoots to begin to turn yellow. Thuja aphids and moths are especially annoying to the plant. When the first signs of damage to the thuja are detected, it is necessary to apply insecticides.
Schutte and tracheomycosis wilt sometimes lead to the death of trees. And it all starts with yellowing of the needles. Then it becomes gray and brown. It is necessary to destroy the plant, otherwise the fungal spores will spread to other plants. The soil should be treated with a fungicide.
To prevent fungal diseases, you need to spray with Bordeaux mixture in the spring. If there are signs of disease, the entire garden is sprayed every 15-20 days.
Sunburn
If spring burning occurs, the needles turn brown. Beginning gardeners don’t even always notice this right away. At first, the tops of the shoots simply dry out a little. But in May the seedlings become distinctly brown. It becomes clear that the thuja is burnt. The spring sun is too bright; it begins to shine and warm when the roots of the thuja are still in the frozen soil. The plant does not receive enough nutrient juices, resulting in a burn.
Even covering with spandbond or lutrasil cannot always help. Sometimes such shelter only causes harm, because due to lack of air the shoots begin to rot. As a preventive measure, you should thoroughly water the thuja in the fall. In spring it is recommended to water the plant lightly warm water, no higher than 40°C, this will help awaken the roots of the plant.
Not only pests are dangerous for thujas. If not properly cared for and watered, they can be susceptible to disease. It is worth considering the main ones: how they are characteristic, and how to cure your favorite trees from them.
Late blight
Late blight is considered the most famous and dangerous fungal disease of thuja. This is a root disease that destroys its top layer. This is reflected in the appearance of the thuja as follows: it withers, turns gray, bottom part the trunk becomes soft to the touch. The tissue under the bark will turn brown and a coating will appear underneath. The root becomes brittle and smells rotten.
Basically, late blight affects thujas growing on soil that is poorly drained; the water here often stagnates.
Treatment
To prevent late blight, it is necessary to frequently water the thuja with fungicides. If the disease nevertheless reaches it and the roots fester, it is best to destroy the tree and replace the soil, since this fungus can live for a long time.
This is a fungal disease that appears in early spring. You can notice it by its yellowed scales. At a late stage of development, the disease affects the entire shoot and it dies.
How to overcome it?
To protect the thuja from this disease, it is constantly fed, and the roots are also sprinkled with limestone. During the period July-October until October itself, it is advisable to spray the thuja with Fundazol (2% solution) every 2 weeks. If you see at least one affected shoot, it should be cut out immediately, and then the disease will not spread further.
If the bark is covered with yellow ulcers that gradually grow and increase in size, your tree has contracted the false scale insect. Treatment should be started immediately, otherwise this disease will cause spots to cover the entire trunk and it will die.
How to treat?
In order to destroy the false scale insect, the following means are used: Rogor, Karbofos, Actellik, Antio.
There are also traditional methods. To prevent this disease, you can wrap the trunk with straw or burlap. Treat the branches with a soap solution containing denatured alcohol (15 grams of soap, 10 ml of alcohol and 1 liter warm water). Another way is to apply special caterpillar glue to the surface (this will prevent pests from reaching it).
Once you notice just a few larvae, try simply brushing them off with a brush or knife without damaging the bark.
Schutte and rust
Fungal diseases manifested by darkening and falling of needles. They begin in the spring and spread throughout the year. Mostly young trees are affected.
How to remove rust and shutte? The best drugs for prevention
To stop the development of the disease, it is necessary to cut off all affected branches and burn them to prevent it from spreading to other coniferous trees. But this doesn't always help.
It is best to treat affected trees with HOM. The consumption rate of the drug is 40 g/10 l of water. This solution should be sprayed on the affected trees twice a season: in the spring (May) and in the summer when the disease reappears. Since both schutte and rust are common to all conifers, it is worth carrying out preventive treatment of the rest of the conifers (all, without exception). It is carried out with the same HOM in the same dose, but only once in the spring.
If there is no effect, you need to shed the trunk circles of the affected trees with Fundazol. The consumption rate of the drug is 20 g/10 l of water - a solution (0.2%) is obtained, which is poured onto the trunk circle of the affected tree once per growing season. There is no need to spray the trees with it, only the soil to destroy the infection in it.
Topsin-M is also used for Schutte: the consumption rate of the drug is 15 g/10 l of water, this solution is consumed for 1 adult plant. Spraying is carried out once in the spring after the threat of night frosts has passed.
Instead of HOM, you can buy Bordeaux mixture. This is an old, but very effective and proven remedy, suitable for many cultures. You don't have to buy it.
Homemade Bordeaux mixture recipe
It's easy to prepare it yourself. The purchased bag contains lime and copper sulfate. This means that to prepare ten liters of a one percent solution you will need 100 g of lime and 100 g of vitriol.
It is prepared like this:
- Vitriol (copper sulfate) is diluted in a glass or wooden container (in no case iron or plastic!). Add up to five liters of water, do the same with lime in another container;
- The diluted vitriol is carefully poured into the slaked lime;
- Stirs. You should get a light blue liquid;
- To understand whether we have poured in a sufficient amount of copper sulfate, we need to take an iron object that is not covered with rust (for example, a knife) and lower it to the bottom of our liquid. The appearance of a red coating means too much;
- This can be easily fixed by adding lime. It is necessary to check, otherwise you can burn the plants.
With this working solution, preventive spraying can be carried out every spring (during the growth of new needles) at the rate of 10 l/100 m².
Bottom line
Proper care And timely assistance will protect and cure your thuja from many possible diseases and pests. But it is also important to remember that shedding and yellowing of needles does not necessarily signal the appearance of some kind of disease.
Thuja often changes color and sheds its needles at the end vegetative period. Appearance may indicate that it is dying. But in fact, it is simply preparing for winter, and the change in the color of the needles is just its protective reaction.
You may be interested in the following information:
- pests of thuja and methods of combating them;