Thuja is an evergreen plant that is resistant to low temperatures, droughts and poor growing conditions. Thuja needles are needle-like or scaly, have a green, yellow, golden or blue color. Many gardeners grow decorative thuja in order to separate their plot from the road with a thuja hedge. The plant is planted both singly and in groups, decorating alleys at entrances, parks, rock gardens, etc. In addition to these benefits, thuja is considered a medicinal plant, because it contains phytoncides and essential oils.
Despite being unpretentious in care and resistance, thuja is susceptible to damage by insects and fungal diseases. Some diseases and insects can cause great harm to thuja and even destroy it. With proper care and timely prevention or treatment, the plant can be saved and the possible consequences of the disease can be warned. When growing thuja, you need to remember that the first signals of problems are falling off and unusual yellowness of the needles. The needles often change color and fall off at the end of the growing season. Such features may indicate a disease, but sometimes this only indicates that the thuja is preparing for winter. But extra vigilance and precaution never hurts.
Phytophthora
Phytophthora is considered the most famous and dangerous fungal disease of thuja. It is a root disease that destroys the top layer. This is reflected in the appearance of the thuja as follows: it withers, turns gray, the lower part of the trunk becomes soft to the touch. The tissue under the bark changes color to brown, and plaque appears below. The root becomes brittle, with a rotten smell.
Fitovtora thuja - a dangerous fungal disease
Basically, late blight affects the thuja growing on the ground, which is poorly drained, the water here often stagnates.
Treatment
For the prevention of phytophthora, it is often necessary to water it with fungicides. If the disease nevertheless reached it, and the roots fester, it is best to destroy the tree, and replace the earth, since this fungus can live for a long time.
Preventing Disease With Proper Care
Fighting thuja diseases is certainly possible, but it is best not to allow it. Thuja, although not a whimsical plant, needs to be looked after, namely regularly watered, fed, pruned and weeded. Most diseases are manifested due to excessive humidity, so excessive watering for thuja is dangerous. It is enough to water every 6-7 days.
It is not recommended to fertilize thuja with some organic matter, namely manure and chicken droppings. These substances contain many microorganisms, due to which thuja can get sick. It is recommended to regularly remove weeds, which also sometimes cause infectious diseases and attract pests. For the treatment of thuja diseases, effective drugs are fungicides and Bordeaux liquid. Insects are killed using traditional methods and insecticidal preparations. Severely damaged parts of the plant must be cut off and destroyed. The main thing is to track the signs of the disease in time and start fighting it!
Brown shoots
This is a fungal disease that appears in early spring. You can notice it by the yellowed scales. In a late stage of development, the disease affects the entire shoot, and it dies off.
Brown shoots
How to overcome?
To protect the thuja from this disease, it is constantly fed, and also the roots are covered with limestone.In the period July-October until October, every 2 weeks it is advisable to spray the thuja with Fundazol (2% solution). If you see at least one affected shoot, it should be cut out immediately, and then the disease will not spread further.
First of all, determine the reason, there are only two of them:
- faeces of animals;
- fungus.
But until the reason is clarified, it is necessary to spray the plant with fungicides 1-2 times against fungal diseases as a preventive measure.
Blackening of the needles occurs when exposed to urine, these areas will be located at a certain height and have a chaotic distribution, like splashes.
In this case, you can:
- put fences to protect the plant from animal access;
- wash with water (if minor impact);
- use repelling aerosols;
- sprinkle with ground pepper;
- spray with growth stimulants (zircon, epin) 2-3 times with an interval of 1-2 weeks.
Zircon
If this is a fungal infection, on closer examination, you can notice fungal spores in the form of black dots or dashes. And start medical procedures to eliminate the fungal disease.
Thuya false shield
If the bark is covered with yellow sores that gradually grow and enlarge, your tree has picked up a false shield. Treatment should be started immediately, otherwise this disease will cause the spots to cover the entire trunk and it will die.
Thuya false shield
How to treat?
In order to destroy the false shield, the following means are used: Rogor, Karbofos, Aktellik, Antio.
There are also folk methods. To prevent this disease, you can wrap the trunk with straw or burlap. At the same time, treat the branches with a soapy solution in dinatured alcohol (15 grams of soap, 10 ml of alcohol and 1 liter of warm water). Another way is to apply special glue from the caterpillars to the surface (this will keep pests out of it).
Once you notice very few maggots, try simply brushing them off with a brush or knife without damaging the bark.
Spider mite
This pest is especially dangerous for trees that grow on dry soil. By the end of summer, the amount of damage increases, since the tick can produce about six generations during this period.
A spider mite wraps around branches so that they cannot receive moisture and sunlight
You can recognize it by the fact that the needles of the thuja are entangled in cobwebs and covered with yellow spots, as a result - they crumble.
How to fight?
At the first manifestation of a spider mite on your thuja, spray it with infusions of dandelion, garlic or colloidal sulfur. With a large lesion, acaricides will help. To prevent the disease, you can spray the tree with cold water. This will increase the humidity and repel the tick.
Schütte and rust
Fungal diseases, manifested by darkening and falling of the needles. They begin in the spring and spread throughout the year. Mostly young trees get sick.
Shute and rust are the most dangerous diseases of thuja
How to remove rust and shute? 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 conifers. But that 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 spring (in May) and in summer with a re-manifestation of the disease. Since both shute and rust are inherent in all conifers, it is worth carrying out preventive treatment for 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, it is necessary to shed the trunks of the affected trees with Fundazol. The consumption rate of the drug is 20g / 10 l of water - a solution (0.2%) will be obtained, with which the near-trunk circle of the affected tree is shed once during the growing season.You do not need to spray them with trees, only the soil to destroy the infection in it.
Topsin-M is also used from the shute: the consumption rate of the drug is 15 g / 10 l of water, this solution is consumed per 1 adult plant. Spraying is carried out once in the spring after the threat of night frosts has passed.
Instead of HOM, you can purchase Bordeaux mixture. It is an old, but very effective and proven remedy, suitable for many cultures. You don't have to buy it.
Homemade Bordeaux mix recipe
It's easy to cook it yourself. The purchased bag contains lime and copper sulfate. This means that to prepare ten liters of a one percent solution, you need 100 g of lime and 100 g of vitriol.
Prepare it like this:
- Vitriol (copper sulfate) is diluted in glass or wooden dishes (in no case iron or plastic!). Add up to five liters of water, in another container the same thing with lime;
- The diluted vitriol is carefully poured into the slaked lime;
- Shuffled. You should get a light blue liquid;
- To understand whether we have poured 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 bloom means overkill;
- The fix is easy by adding lime. It is necessary to check, otherwise the plants may be burned.
This working solution can be used for preventive spraying every spring (during the period of growing new needles) at the rate of 10 l / 100 m².
The most common thuja diseases and their treatment
Thuja pests
Most thuja pests are oligophagous and can develop on plant species from the cypress family: junipers, thuja and cypress trees. They occur and harm mainly in the southern regions of the European part of Russia, in the Crimea and the Caucasus.
A few pests of thuja belong to three ecological groups:
- sucking
- minerals,
- xylophages.
Sucking pests
Sucking pests of thuja suck the juices from needles, shoots and immature cones. These include two species of coccids and one species of aphids.
Thuya false shield
The most harmful to thuja are Juniper Scale (Carulaspis juniperus) and Thuya false shield (Parthenolecanium fletcheri)... In the juniper scale, the scutellum of the female is brown, elongated-oval, 1.9–2.0 mm long. This species is found in the southern regions of the European part of Russia, in the Caucasus and Central Asia. In thuja false scutellum, the body of the female is strongly convex, almost spherical, 3–3.5 mm long, yellowish-brown and brown in color. This false shield is found and damages in the parks of the European part of Russia, forests and parks of the Crimea, the Caucasus and Central Asia.
Much less often on thujas can be found thuja aphid (Cinara juniperina)... This species belongs to monoecious non-migratory aphids. The integument of the body of the pest is grayish-brown, with a light waxy coating. Aphids feed on small colonies on the underside of 2-3-year-old shoots. The needles on the shoots damaged by aphids gradually turn yellow and eventually fall off. Thuja aphids are found everywhere.
Miner insects
Miners are insects whose larvae feed on the tissue of leaves or needles, making passages in the thickness of leaf blades or a growing shoot.
Thuja's scaly leaves gnaw through tiny caterpillars tuyeva miner moth (Argyresthia thuiella)... The tracks of the caterpillars are clearly visible when looking at the needles into the light. The damaged needles turn brown (turn yellow), and the tops of its shoots die off. After the caterpillar emerges, well-visible small holes remain in the yellowed needles. The harm is insignificant. The thuja mining moth is found everywhere.
Damage from thuja miner moth
Stem pests
Stem pests, or xylophagous insects, feed on the bark, bast and wood of branches and trunks.Most of them settle on strongly weakened and dying plants. Three types of bark beetles are known on thujas: thuja beetle (Phloeosinus thujae), juniper bark beetle (Phloeosinus aubei), which can be found only in the forests and parks of the Crimea and the Caucasus.
Thuja bark beetle
How to strengthen tree immunity with top dressing
The appearance and condition of most trees depend on the balance of nutrients and their supply. With a lack of iron in the ground, the needles turn white and yellow on individual shoots, and with a lack of phosphorus, they acquire a red-violet color. If there is little nitrogen in the soil, then the plants begin to grow worse.
That is why foliar and root feeding is necessary. For these purposes, special fertilizers for conifers are used. Plant resistance to errors in care and negative factors is increased by biologically active drugs and growth regulators. Many gardeners use the following remedies to strengthen the immunity to water or temperature stress, improve the survival rate of seedlings and the intake of nutrients:
- Nikfan;
- Zircon;
- Humisol;
- Immunocytophyte;
- Epin-extra.
The appearance and condition of the plant depends on nutrients. If there is not enough iron in the soil, then the tree gets sick and turns yellow in some areas. And if there is not enough phosphorus, then the thuja becomes red-purple in color. Plant growth is affected by the amount of nitrogen in the soil.
For this, you need to feed the plant. Use special fertilizers for conifers.
