Scabies: Causes and control methods

Scab scab affects many varieties of agricultural crops, fruit trees, bushes and vegetables. Crusts and sores form on the surface of leaves, fruits, root crops, then they crack and the infection penetrates through the micro cracks. Although scab damages superficial tissues, the disease is difficult to treat.

Scabies: causes and methods of control

Scab – a description of the disease

Scab and scab rot is a specific pathogen of each fruit and vegetable crop. That is, the disease will not spread from potatoes to beets, or from apples to pears. However,The signs of the disease are similar:

  1. Micro cracks on the surface;

  2. Peeling of the skin;

  3. Fruits, leaves, stems, tubers covered with pustules, warts, spots.

In the neglected stage, the leaves wither and fall off, the fruits take an ugly shape, not to be stored, as they quickly begin to rot.

Scabies: causes of formation

Despite the fact that each plant species has its own pathogen scab, the disease can form on all crops at the same time, since the causes of the disease are the same for all:

  1. Excessive soil moisture.A man can not always control the moisture of the soil, because in addition to artificial irrigation, there is also a natural factor: melting snow, precipitation.

  2. Overgrowth of plantings.When fruit trees, bushes or vegetables are overcrowded, the soil quickly becomes poor and plants cannot get enough nutrients. Due to this, crops quickly become exhausted, weaken, and the disease seizes more and more territory.

  3. Variety instability.When buying, it is worth choosing varieties of vegetable and fruit crops that are resistant to scab.

  4. Lack of variety. The more monotonous the planting, the faster the disease can progress. In a garden with the presence of different varieties will be observed a positive trend.

Therefore, in order to avoid the spread of the disease, it is recommended to observe crop rotation, plant fruit tree seedlings at an optimal distance, conduct preventive treatment of the garden.

How plants are affected by scab?

The fungus develops quickly in conditions of high humidity of over 70%, temperatures between +15°C and +20°C, and soil acidity levels of 7 pH.

Plant leaves, fruits, stems are covered with black or olive-brown spots. Vegetables, root crops, fruits, affected by scab, rot quickly. With severe damage, all leaves fall off the tree, there is low growth and no fruiting.

Microorganisms and bacteria causing the disease are found in dry, loose soils. Spends the winter near the tree, huddling in the fallen leaves. As long as there is no favorable weather, the pathogens do not manifest themselves. As soon as the humidity of the soil and air increases, the microorganisms intensify their activity.

It is a shame that scab can not be considered in its early stages – it does not manifest itself in any way. Only when the disease passes to the late stage, spots, tubercles and pustules appear on the leaves and fruits, and the degree of infection of celery and potatoes can be determined only after harvesting. Not infrequently, scab leads to the death of the entire crop.

Scab by itself does not lead to death. Plants die as another infection enters the wounds.

Potato scab

Scabies: causes and control methods

Potato plants suffer most from potato scab. In favorable conditions the disease can destroy up to 90% of the crop.

Types of potato scab:

  1. Ordinary. As a result of the disease, irregularly shaped spots first appear on the tubers, then shallow ulcers. As they progress, the spots proliferate and coalesce. Eventually cork inclusions form in their place. The first sign of the disease can be detected when digging tubers – their surface is covered with a plaque in the form of spider webs, which disappears after the tubers dry out.

  2. Lumpy scab.Potato scabies attack the crop during its growth. But the disease itself manifests itself during the storage of the crop. Round pustules colored in the tone of tubers, different in shape – protruding, depressed, flat. No rot under the rind.

  3. Black or rhizoctoniosis. Variety reduces yields by 20%. The affected plant has twisted leaves, the roots are covered with mold, the plant dies.

  4. Silver.It appears as tiny spots of light brown color. Potato scab reaches its peak of development in the spring. Pressed spots with a metallic sheen form on the affected areas. Tubers lose moisture and become wrinkled.

  5. Scabby.The tubers are infected through soil and poor quality material. The pathogens penetrate through the wounds into the stolons and roots. The root system is covered with galls – white outgrowths, gradually darkening. Pustules that look like warts form on the surface of the potato. At the stage of maturity, the wart formations dust a powdery mass colored brown. During storage, tubers are affected by dry rot and phytophthora.

After scab infestation the site becomes unsuitable for growing solanaceous crops within 4 years.

Tubers, affected by scab, are used for planting or fed to livestock. In rare cases the disease damages vegetative parts of the crop, as well as the root system.

Potato scab: ways to fight it

For preventive purposes it is recommended to observe crop rotation – it is allowed to grow potatoes in the same area once in 3 years. After mowing green mass will have to be removed and burned further from the site. Do not leave tubers and plant debris in the soil. Other recommended solutions are:

  1. Choose scab-resistant varieties for growing. These include: Charodey, Lasunak, Alena, Filatovsky, Elizaveta.

  2. Before planting the tubers, about a month beforehand review the planting material and put aside diseased tubers and tubers with visible signs of disease. Now you need to let the potatoes warm up in the sun for 21 days at a temperature of +14-15°C. After that another sorting is necessary to remove the damaged tubers.

  3. Immediately before planting, about a day before it will have toProtect the tubers with preparationsPatron or Tubershield. To prepare a working solution in 1 liter of water, you need to dilute 70-85 ml of the agent. It is more convenient to treat tubers with a fine sprayer, so you can guarantee an even distribution of the product over the surface of the tubers.

  4. During the planting season, potatoes are treated with chemical preparations Maxim, Albit, Hom or Ordan. Prepare the working solution according to the instructions.

  5. Optimal environment for tuber growth – slightly acidic. If the soil is strongly acidified, it is recommended to lime the soil by introducing lime, chalk or other substances containing calcium. This procedure should be carried out at least one year before the planned planting.


Scabies can affect 160 kinds of plants, so the disease may affect all plantings on one plot in one year.

Scab of sugar beets

Scabies: causes and control methods

Ordinary scab develops as a result of the vital activity of the fungi of the causative agents:

  1. A. Violacea;

  2. A. Albus;

  3. A. Cretaceus;

  4. Actinomyces scabies.

On the affected surface of the root crops, a rough crust forms, which eventually cracks, peels. Beets rot as a result of microorganisms getting into the microcracks, which cause rot. Near the haulm, the root crop becomes soft, by the leaves you can not pull out the beets, they remain in the ground, and in the hands – the haulm.

If beets grow in a heavy soil with an acidity equal to 7.5 pH, the root crops lose sugar content and their weight. The fungus winters in the ground, resumes its activity in the spring.

Beet scab: ways to combat it

When planting vegetables, it is important to follow the rules of crop rotation – never plant beets in the same place 2 years in a row. Do not grow in an area where potatoes grew last year. Other than that:

  1. Regular soil loosening, Remove weeds, haulm, and rootstock to help avoid scab infestation.

  2. The fungus develops in soil with a high alkalinity index. Do not put large amounts of straw, wood ash, manure in the soil.

For more alkaline soils, apply orthophosphoric acid at a rate of 2 m2 – Dissolve 2 g of the product in a bucket of water.

Apple scab

Venturia inaequa

  • s – the causative agent. The fungus does not attack the branches and shoots, but overwinters under the tree in fallen leaves. As soon as weather conditions become favorable, the pathogen attacks the foliage – a soft olive-colored coating forms on the underside. Over time, it turns a grayish red color. The fruits become tasteless, their nutritional value decreases, the pulp and skin turn black.

    Young fruits suffer from scab. A dense cork forms on the skin, the fruit does not develop, falling to the ground. In rare cases, the disease appears after harvesting. With the development of scab disease covers all parts: shoots, flowers, bark. The apple tree loses strength, gradually withers.

    Apple scab: Ways to fight it

    Plan the planting of apple trees in such a way that each tree has enough space and space. Regular formative and sanitary pruning is recommended to provide access to light in the center of the crown. In addition, the following measures will need to be taken:

    1. Planting varieties with high resistance to scab on the plot. Antonovka, Tsyganochka, Prima have proven to be good. Thanks to the work of breeders, new varieties resistant to cereal scab appear on the market every year. Keep an eye out for novelties.

    2. Remove fallen leaves annually, Burn the damaged shoots, fruits and leaves.

    3. For preventive purposes, the apple tree can be treated with garlic infusion. For its preparation you will need to infuse 2 liters of boiling water for 24 hours with 250 grams of crushed garlic. After a day, strain, dilute with water to a volume of 8 liters and add laundry soap – 30 g.

    To increase the immunity of plants to scab, gardeners spray apple trees with preparations containing silicon. Remedies perfectly heal the plantings and increase resistance to diseases, especially scab.

    Pear scab

    Scab and scab: causes and control methods

    Venturia pirina is the causative agent of pear scab. The fungus spends all winter on young shoots. As soon as it becomes warm and humid, the pathogen begins its destructive activity. The activation period is when the buds open. The young leaves are covered with a soft olive-colored plaque to the touch. The spots may also be greenish-brown. They contain a huge number of spores that affect the entire pear. The infected leaves will curl and eventually fall off, and the flowers will also drop early. The disease leads to a reduction in fruit formation. Pears that do set, do not grow, look diseased.

    Through the spots on which cracks form over time, the infection penetrates inside the fruit. Affected fruits are not suitable for food, they can not be canned, cooked jam.

    The bark on the diseased tree is swollen, covered with blisters. A plaque with spores is clearly visible on top. The disease is spread by insects, wind, birds. Scab scab spreads to pear trees in the vicinity. Spores lurk on the branches and spend the winter, and in the spring they begin to attack the plantings.

    Pear scab: ways to combat it

    As soon as all the leaves fall off the fruit trees, it is recommended to collect them completely and burn them away from the plot. Gardeners do formative pruning once a year to allow oxygen and light access to all vegetative parts. Other than that:

    1. Buy scab-resistant pear varieties: Chizhovskaya, January, Muratovskaya, Memory of Yakovleva, Rusanovskaya.

    2. For preventive purposes, pears should be sprayed with copper chloride or Bordeaux fluid. Their chemical preparations are allowed to treat Skorom, Abiga-Pik, Raikom. The first treatment – immediately after bud blossoming, the second – after the flowers fade, the third – at intervals of 14 days after the previous treatment.

    In late autumn, it is recommended to dig over the soil in the stump circle to break the rest of all microorganisms. And you also need to promptly remove all fruits with visible signs of disease, affected leaves and shoots – burn further from the site.

    Scab scab of cherry and bird cherry

    Scab: causes and methods of control


      Inia cerasi – scab fungus on cherry and bird cherry. As a result of its activity, fruits are damaged (gray streaks are formed) and leaves (spots are colored brown). Affected leaf plates curl into a tube, dry and crumble. Fruits do not mature, so green and fall off the trees. Infection occurs through microcracks in mature fruits.

      The pathogen spends the entire winter near the tree, in the remnants of foliage. In spring, when the weather becomes wet, the fungus affects the fruit tree. In a short period of time almost all the leaves fall off, the fruits become unsightly, lose taste.

      Scab and cherry scab: ways to combat it

      With the onset of spring it is necessary to carry out formative and sanitary pruning, as a result of which remove all damaged, improperly growing shoots and remove them from the plot. At the same time it is worth to dig over the soil in the stump circle. More:

      1. To prevent scab, vineyards are treated three times a season with bordeaux liquid. Working solution: 100 g of the product per bucket of water. The first spraying – the stage of the green cone, the second – 3 weeks after flowering, the third – in the fall, after the harvest.

      2. If scab has appeared on ripe fruit, table salt will help to save the crop. To prepare the solution you need to dissolve 1 kg of salt in a bucket of water. Chemical consumption for one mature tree is 2 liters.

      Throughout the season, it is necessary to monitor the condition of the trees, so as not to miss the moment and in time to carry out treatment against the disease.

      Scab on gooseberries

      Scabies on gooseberries are often confused with powdery mildew. Before you start treating the disease, it is worth making sure what gooseberry actually diseases.

      To prevent the development of the disease it is necessary in early spring, while the buds are still awake, to treat the plantings with a 7% solution of urea. Wet all the vegetative parts of the plants well during the work.

      In autumn, pruning unnecessary shoots, removing damaged, dry, digging the soil in the root circle is carried out. After that it is necessary to spray a 7% solution of urea.

      To treat diseased bushes, the culture is treated with a 2% solution of Bordeaux liquid, the drugs Horus or Aktara.

      Scabies of currants

      Unlike gooseberries, currant bushes are less affected by scab.

      For preventive purposes, plants are treated in the spring with a 7% solution of urea. At the first signs of the disease – with Actara, Horus or Bordeaux liquid.

      The scab progresses in conditions of high humidity along with high air temperature. If you follow the agro-technical methods of cultivation, the probability of scab development on fruit and vegetable crops is reduced.

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