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If the branches of an apple tree turn black, this indicates the appearance of black cancer. The disease is caused by fungi and can lead to irreversible consequences, including the death of the tree. Therefore, treatment begins as early as possible. All affected parts of the black bark are cleaned with a wooden scraper, after which they proceed to treatment with a fungicide. For these purposes, copper or iron sulfate is used. Then they coat the wounds with garden varnish and leave to dry.
Why does the trunk and branches of an apple tree turn black?
Blackness on the trunk of an apple tree indicates the development of black cancer (it is often called “Antonov fire”). Pathology can affect any part of the tree, but it poses a particular danger to the trunk. If the trunk is affected, such a plant can only be helped at the initial stage. Very often a tree has to be cut down because treatment is no longer possible or is extremely problematic and costly.
The causative agent of the disease is a dangerous marsupial fungus, which belongs to the Botrispherae family.It penetrates through damage to the bark that occurs due to age-related reasons, as well as due to unfavorable weather conditions and improper care.
The reasons for the appearance of black spots on the bark of an apple tree can be different, the most common are:
- Rare feeding, unbalanced fertilizers.
- Irregular watering. This factor has a negative impact after a bountiful harvest, when the tree is exhausted and requires special care.
- Sunburn and frost damage lead to peeling of the bark, and it is in these places that infection can penetrate. If the stem is not whitened, it becomes very hot, which can lead to peeling of the surface layer.
- Sudden temperature changes also lead to similar consequences. For example, if during the day the heat reached +30 °C, and at night the temperature dropped to 8-10 degrees, the bark may also crack.
- Too late spring or early autumn pruning, when dangerous fungi can penetrate into the resulting wounds.
With age, trees weaken and are poorly resistant to diseases, infections and adverse weather conditions.
The main cause of black cancer is pathogenic fungi that penetrate the tree bark
Blackness at the core
If not only the surface, but also the core of a branch or trunk turns black, this is the most dangerous phenomenon. The disease is already advanced, and there is little chance of recovery. But you can try to cure even such an apple tree. The dead part is cut out, slightly including healthy tissue. Then they are treated with a powerful fungicide.
The trunk of the apple tree has turned black from below
If a young or old apple tree has a blackened trunk at the bottom, this also indicates the development of black cancer.Treatment must be radical. The affected part should be cut out and treated. Next, a bridge graft is made in order to save the upper part (crown). But if the lesion is severe, this method is ineffective.
Black bark on an apple tree
Black bark on apple tree branches is a less dangerous option. If the cancer has affected only the superficial layers, it is quite possible to cope with it. The treatment method is the same - the affected part is cleaned off, after which it is treated with a solution of copper sulfate or other strong fungicide.
Main signs of the disease
Cancer infection can be determined not only by black spots on the bark of the trunk and branches, but also by a number of other signs:
- Spots on leaves - they appear in early spring, literally immediately after blooming. Moreover, the spots are dark, violet in color, and round in shape. Appear only on the outer side of the leaf plate. Gradually increase in size and become brown, while the edges remain purple. Then rings and black formations - pycnidia - form on them. This is the name given to the fruiting body of the fungus, which is the source of the disease.
- Then the foliage dies quite quickly and falls off prematurely. An apple tree may lose a significant part of its leaves as early as June-July. This has a bad effect on productivity. Some of the ovaries will fall off, and few fruits will be formed.
- Brownish spots appear on apples en masse. At first they are small, then they increase in size, covering almost the entire surface. Black pycnidia appear on the fruits, which appear in the form of circles.
- Some apples mummify, harden, and they hang even in the fall after the leaves fall. They acquire a pure black color, like bark (without a blue tint). May also be brown.The surface is rough.
An apple tree trunk affected by black cancer can be identified visually
Features of blackening of the trunk of an apple tree
The symptoms of the disease are the same - the bark of the apple tree turns black, and in advanced cases, the underlying, deep plant tissues also suffer. In many cases, additional symptoms may be added to the standard ones. For example, the bark of an apple tree may become wet or, conversely, dry out. Often black spots or white growths appear on the surface.
Drying
Since the fungi that cause black canker are parasitic on the apple tree, this can lead to drying out of the surface of the bark. This phenomenon is especially often observed during drought, as well as with insufficient watering. Treatment is standard - cut out the affected areas, process and treat with garden varnish or a mixture of clay and manure (1:1).
The appearance of wet areas
If the affected black areas of the bark become wet, this indicates the development of putrefactive bacteria that decompose dead wood. Treatment also involves stripping and treating with copper sulfate. This drug effectively destroys not only fungi that cause black cancer, but also bacterial colonies.
The appearance of white growths
White growths indicate the birth of the mycelium of tinder fungi. They only grow on dead wood because they cannot feed on healthy living tissue. Therefore, the appearance of the tinder fungus itself indicates an advanced stage of the disease. You can try to clear it of black bark and treat it. But it is not always possible to cure.
Bark cracking
Cracking of the bark is one of the characteristic symptoms of cancer not only of apple trees, but also of other fruit trees (pear, apricot, peaches).In this case, all affected areas are cleaned to healthy areas, after which they are treated with copper sulfate and garden pitch. But if the trunk is affected by black spots by more than 50%, the tree will have to be uprooted and burned.
Appearance of black spots
If black spots appear on the trunk, they should be removed as quickly as possible. Clean and disinfect with copper or iron sulfate. Otherwise, the black spots will quickly turn into cracks and deep wounds. Such branches remain to be cut down to a healthy place, and the cuts are sprinkled with crushed charcoal powder.
First of all, it is necessary to carry out a thorough cleaning
What to do if the branches and trunk of an apple tree have turned black
Regardless of where exactly the bark has turned black, the treatment looks the same:
- First you need to clean the affected areas. For this, use a wooden scraper, since metal objects will not work. Stripping is done to a healthy part of the bark or wood with a slight grip to protect against the possible spread of infection.
- The diseased bark is removed with a margin of 1-2 cm, branches - by 10-15 cm. In the case of the trunk, it is advisable to remove it with a large margin of up to 15 cm.
- Treat with a solution of copper or iron sulfate of a sufficiently high concentration of 3-5%. Other fungicides are less effective because not all drugs act simultaneously on fungi and bacteria.
- Cover the cuts where there used to be black bark. To do this, use garden pitch (you can buy it or make it yourself) or a mixture of clay and manure in equal quantities. You can also take an ordinary clay mash.
Along with vitriol, gardeners recommend using the Vitaros contact-systemic fungicide.It contains two active components at once - carboxyl and thiram. It has a gentle effect on the apple tree, without burning the plant tissue. Consumption rate – 20 ml per 10 l. The resulting solution is used to treat areas where there was previously black bark and healthy trees.
Another suitable remedy is the Strobi fungicide. It contains kresoxim-methyl. The drug has a universal effect and copes well with most fungal diseases. It suppresses the growth of mycelium and inhibits the processes of spore formation. Effective even when used in cool weather (1-5 degrees Celsius). Consumption rate – 2 g per 10 l.
Damaged areas are treated with garden varnish
Prevention measures
Black cancer is a dangerous disease that in advanced stages cannot be treated and leads to the death of even young apple trees. To prevent such consequences, it is very important to follow basic preventive measures. Experienced gardeners recommend following the following rules:
- Even if the garden is healthy, the bark needs to be inspected regularly, which is especially important for old apple trees. When black spots appear, complete cleaning and treatment with fungicides must be carried out.
- Every spring they plan sanitary pruning - dry, old, withered and obviously diseased branches are removed. If necessary, this can be done even during the season.
- Select varieties of apple trees that are adapted to growing in a particular region. These must be frost-resistant and drought-resistant varieties.
- It is necessary to observe the timing of pruning, carrying out it in cool weather (up to 5-7 degrees Celsius). In this case, you should always treat the blades of tools with a weak solution of potassium permanganate, and sprinkle the wounds with crushed charcoal or lubricate them with garden varnish.
- Maintain proper watering and do not overfeed with nitrogen fertilizers. This leads to cracking of the bark, as a result, through the resulting wounds, the infection quickly penetrates into the deeper layers of tissue.
- Treat for pests every spring. In summer, if necessary, use chemical or folk remedies. Many insects carry spores of dangerous fungi, so it is important to combat pests in a timely manner.
- Regularly whitewash the trunk to a height of at least 30 cm from ground level.
Conclusion
When the branches of an apple tree turn black, this is the main sign of the development of black cancer. The pathology is infectious, but there is practically no threat to healthy trees, since the pest penetrates through damaged bark. To prevent black cancer, it is recommended to regularly prune, inspect trees, and ensure normal watering and care.
