Content
Scab on currants appears in wet soil conditions when the watering rate is systematically violated. It manifests itself as olive-brown spots on the foliage, after which it turns yellow and falls off. In this case, the shoots become deformed and then completely stop growing. Folk remedies and fungicides are used for treatment.
Signs of appearance
Scab is an infectious fungal disease that affects fruit and berry crops, including currants. All above-ground parts of the plant - shoots, foliage, berries - suffer, which inevitably leads to loss of yield. Colonies feed on substances from leaf tissues. They multiply and take over large areas, after which the foliage dies off.
Brown spots appear on currant berries due to scab, and the skin cracks. Because of this, bacteria penetrate the pulp and lead to rotting. The described processes occur especially well during wet and cool weather. The longer the rainy season continues, the more the bushes suffer.
The main signs of scab on currants:
- dark brown spots on the surface of the leaves;
- yellowing of foliage;
- young shoots die off;
- the buds turn black;
- the fruits are covered with a brownish film;
- they crack and rot.
In its development, the infection goes through four main stages:
- Initial - fungi release spores that infect young shoots and foliage. As a result, spots of dark color (olive color) appear on them. They are velvety, uneven - these are the spores of the pest. The spots increase in size, become brown and then cover almost the entire leaf. The plant tissue on the surface dries out and crumbles.
- Progressive - the infection spreads to the developing flowers, and then to the ovaries. As a result, a coating of viscous, viscous consistency appears on them. Leaves and flowers dry out and fall off, and many fruits never form.
- Critical - currant leaves and berries are covered with a brown coating, the structure reminiscent of felt. The shoots stop growing, they become deformed, dry out and begin to crack. The young growth bends and then quickly dies.
- The last stage of scab development - new currant shoots no longer grow. If leaves appear, they immediately fall off, and cracks form on the skeletal branches. At this stage, the fungus re-infects the bush, which aggravates the course of the disease.
Currant leaves affected by scab can be easily identified by visual inspection
Why is scab dangerous?
Scab is very dangerous because it affects not only currants, but also other fruit and berry crops. This leads to negative consequences:
- the berries on the bushes stop ripening;
- fruits that have already formed crack and rot;
- they contain bacteria that can be dangerous to human health;
- productivity is greatly reduced;
- the appearance deteriorates - the foliage falls off, the shoots curl and dry out;
- neighboring plantings are also infected.
Another danger is associated with the fact that fungal spores overwinter under the currant bark. If you do not treat the bushes, they will survive the frosts and begin new attacks in the spring. This can lead to the death of the plant.
How to deal with scab on currants
It is possible to get rid of scab on currants - for this you need to use different means. If the disease is already advanced, chemicals are used. If it is at an early stage, it is permissible to use folk remedies. Often both groups of methods are combined in order to achieve quick results.
Traditional methods
Among the popular folk remedies for currant scab are the following:
- Ash infusion – 200 g per 10 l. It is kept for 24 hours, then the bushes are sprayed or the root zone is watered.
- Infusion of 300 g of tobacco dust in 3 liters of hot water - prepare for three days. At the same time, make an infusion of garlic cloves (3-4 heads) in 3 liters of hot water. Leave for 3 days, then mix and add a teaspoon of red pepper, as well as liquid soap (2 tablespoons). Shrubs are treated before the buds begin to swell.
- Potassium permanganate solution – 5 g per 10 l. Spray three times per season: in early spring, on the eve of flowering and after harvest.
- Horsetail infusion - 3 kg of fresh grass is poured into a bucket of water at room temperature, infused for four days, filtered and treated with bushes 3-4 times per season.
The bushes are sprayed in the late evening in dry and windless weather.
Chemicals
To combat scab on black and other varieties of currants, chemical agents - different types of fungicides - are especially effective:
- "Fundazol" is a water-soluble drug, the active ingredient is benomyl. Penetrates plant tissue through the root system, inhibits the proliferation of scab fungi. Resistant to precipitation, provides a protective effect for 2-3 weeks.
- "Shavit F" is a contact-systemic fungicide based on two active ingredients (triadimenol and follette). It disrupts the biosynthesis and respiration of scab fungi and prevents reproduction. Has a protective effect for up to three weeks. It is safe for soil bacteria. Used for both treatment and prevention.
- "Paracelsus" is a fast-acting drug based on the active ingredient fletriafol. It quickly spreads through currant tissues, disrupts reproduction processes, and prevents the development of infection. Valid for up to three weeks.
- "Skor" is a drug based on the active ingredient difenoconazole. Penetrates into currant tissue, inhibits the growth of scab fungi. The first results are noticeable the very next day. In this case, the protective effect lasts up to 10 days. To achieve better results, it is recommended to process currants at a temperature of at least 15 degrees.
- "Chorus" is a drug in granules based on cyprodinil. It has a systemic mechanism of action. Inhibits the growth of scab mycelium and interrupts the life cycle. Provides a protective effect for a period of up to 15 days. The product can be used for processing even at a temperature of +2 °C.
Prevention measures
To prevent scab on red and other types of currants, it is necessary to take certain preventive measures.The main methods are the treatment of currant bushes with special means, as well as agrotechnical techniques described below.
Urea solution
Urea (urea) is an organic nitrogen fertilizer. It dissolves well in water and is quickly absorbed by plant cells. Used for feeding and treating currants against scab. Spraying begins a week before the first frost. To do this, prepare a solution (ratio of 35 g per 10 liters of water). This volume is enough for 6-7 adult bushes.
inkstone
Iron sulfate is an aqueous solution of ferrous sulfate. It destroys scab on the surface of leaves, shoots and other above-ground parts. Used to process currants in early spring and late autumn. For spraying, take 35 g of the substance and dissolve it in 10 liters of water.
To prevent scab, bushes are treated several times a season.
Copper sulfate
Copper sulfate is a solution of copper sulfate. It is used to prevent scab, as well as certain pests, such as scale insects, gall aphids and glass beetles. The concentration and processing time are exactly the same as in the case of iron sulfate.
Agrotechnical measures
To prevent scab and other diseases, it is important to provide good care for currants. The main activities are as follows:
- The bushes are not planted too densely, leaving a minimum interval of 2 m between adjacent holes.
- The mulch is regularly changed with the onset of spring and autumn.
- The trunks are constantly cleared of growths of lichen, moss, as well as dead bark.
- In the fall, pruning is carried out, and all plant debris is taken away and burned.
- Currant leaves are also burned; they should not be used as mulch.
- For cultivation, it is recommended to use currant varieties that are resistant to scab. These include: Valovaya, Selechenskaya, Rolan, Rowada.
Conclusion
Scab on currants is very dangerous, since the disease is infectious and can affect neighboring plants. The fungus develops in several stages, and its spores overwinter in the bark, after which they again parasitize the bushes. Therefore, plants should be regularly inspected, as well as preventive treatments performed in early spring.
