Content
Currants, like any crop, can suffer from diseases and pests. Most often, the lesion appears as red or white spots. If measures are not taken in time, you can lose the harvest and the bush itself. Before treating brown spots on currant leaves, determine the cause of the lesion. Next, choose the appropriate method: folk remedies, the use of chemical or biological drugs.
Why do currant leaves have red leaves?
Currant is a berry bush with green leaves. They have from 3 to 5 lobes and large teeth. Their leaf blades are smooth and shiny and have a specific smell. When red spots appear, the integrity of the leaves is compromised and the plant loses its decorative appearance.
Reasons for the spread of brown or red spots on currants:
- initial stage of anthracnose disease;
- spread of fungus that causes rust;
- the appearance of a dangerous pest - the red gall aphid.
In autumn, the color of currant leaves becomes yellow or burgundy.Leaf fall ends in September or October, depending on weather conditions. Reddening of leaves in autumn occurs due to the change of season. If they change color ahead of time, then this is already an alarming sign for the gardener.
Causes of brown spots on currant leaves
Depending on the cause of the lesion, the method of treatment is chosen. To accurately diagnose why the red currant leaves are covered with red spots, inspect the entire bush.
Anthracnose
Anthracnose is a disease of trees and shrubs caused by a marsupial fungus. It is widespread in Western and Eastern Europe, America, and Russia. The northern and western regions with a temperate climate and frequent rainfall are at risk.
The defeat spreads to all types of crops: black, white and red. Brown spots appear on currant petioles and leaves. Their size is about 1 mm. Then spores develop on them in the form of black tubercles. Black depressed spots are observed on the petioles.
The harmful fungus remains in fallen leaves for the winter. Infection begins at the end of May. Leaves that bloomed 25 to 30 days ago are most susceptible to the disease. Anthracnose on currants develops at the end of flowering. If measures are not taken in a timely manner, the peak of the defeat will occur in July and August.
The fungus grows in drops of moisture. The optimal temperature for its development is from +15 to +20 °C. Under such conditions, the incubation period lasts 8 - 12 days. On blackcurrant, the disease appears at lower temperatures.
When red spots appear, the development of the bush slows down and does not receive the necessary nutrition. If treatment is not started, its frost resistance will significantly decrease. In spring, the bush may lose half of its shoots.
Gall aphid
The cause of spots on red currants can be gall aphids. In early spring, its larvae appear and crawl across the plants. They have an ovoid body up to 2 mm long and a pale green color. Up to 20 generations of gall aphids are formed per season.
As a result of the activity of the larvae, the leaves at the tops of the shoots change color and shape. Red swellings - galls - are diagnosed on currants. These are neoplasms that arise as a plant’s defensive reaction to a pest.
The gall aphid is widespread throughout Eurasia. The insect is found in both southern and northern regions. After red spots appear on the leaves, the plants give little growth and yield. Young leaves suffer the most from gall aphids. If the leaf plate has already formed, then red swellings do not appear on it. The lesion will take the form of small dotted spots.
Rust
Rust is a disease of currants and other crops that belongs to the fungal group. The first symptoms appear after flowering on the shoots and leaves. They look like large round spots of yellow or orange color. Often such spots have a red border. By mid-July, black dots – fungal spores – appear on the leaves.
Over time, the red spots swell and become covered with gray growths filled with black spores. The disease is common in the southern regions: in Moldova and the North Caucasus. Without treatment, the red leaves fall off prematurely, the yield of the bush decreases, and the taste of the berries deteriorates.
How to treat red leaves on currants
To treat currants for red spots, chemical or biological drugs are chosen. They are alternated with folk methods, which are also used to prevent red spots on currants.
Chemicals
Chemical preparations are most effective against red spots. Before using them, you need to read the instructions. Be sure to follow the dosage. It is best to carry out treatments before fruiting or after harvesting the berries.
To treat currants, prepare a solution. It is sprayed on the leaves using a spray bottle. The bush is processed on a cloudy day or in the evening, when the sun has disappeared. To protect the skin and vision, wear gloves, goggles or a special suit.
If red raised spots on the leaves of currants are caused by diseases, then use the following remedies:
- Bordeaux mixture. A solution based on lime and copper sulfate. Acts against various fungi. The product adheres well to the leaves. To treat red spots on currants, a solution with a concentration of 1% is prepared. Treatments are carried out no more than once every 14 days;
- Copper oxychloride. An alternative to Bordeaux mixture. It looks like light green crystals. Copper compounds have a detrimental effect on microorganisms. When treating currants, the solution lasts 10 - 12 days;
- Abiga Peak. A fungicide intended for the treatment of currant diseases. Add 40 ml of suspension to 10 liters of water. The working solution evenly covers the leaves and is not washed off by rain. The product is effective at low temperatures, promotes the formation of chlorophyll, and increases plant immunity.
If red blisters on currant leaves are caused by gall aphids, then resort to insecticides:
- Aktara. An enteric contact drug that is effective at low humidity and high temperature. The solution is not washed off with water. Spraying is carried out before the buds appear or after the berries are removed. For 5 liters of water, 1 g of the drug is needed. Prepare 1 liter of solution per bush. The waiting period is up to 2 months;
- Ditox. Systemic drug for the control of aphids and other insects. It is highly efficient. The pest dies a few hours after treating the bush;
- Spark. An effective remedy against various insects. Works even in hot weather. Iskra is safe for humans, animals, birds and beneficial insects. Add 5 ml of suspension to 10 liters of water. Spraying is carried out when the pest appears en masse.
After treating the currants from pests, they begin to treat them. The bushes are fed with mineral complexes. In the spring, apply urea or other nitrogen-based fertilizer. In summer and autumn, a solution containing superphosphate and potassium sulfate is prepared.
Biological drugs
Biological drugs suppress the activity of harmful fungi. Some of them are used at any stage of bush growth. The active substances do not penetrate the plant tissue and do not accumulate in the fruits
To treat red swollen spots on currant leaves, the following biological preparations are used:
- Tiovit Jet. A sulfur-based product for the treatment and protection of currants from fungal infections. To prepare the solution, 20 g of the substance is required per 5 liters of water. Currants are processed during the growing season;
- Agromedicine. Systemic fungicide to protect the garden from fungal diseases.Spraying is carried out before the formation of buds or after picking the berries. The consumption rate is 10 ml per large bucket of water;
- Tsikhom. A new drug that provides treatment and protection of currants from fungus. Spraying requires 10 ml of fungicide per 10 liters of water. Prepare no more than 1 liter of solution per bush. Treatments are carried out in early spring or autumn.
Biological preparations against gall aphids:
- Akarin. Insecticide with rapid action on insects. 8 - 16 hours after treatment, the aphid loses motor activity and dies. The bush is sprayed during the growing season. For 1 liter of water, 2 ml of suspension is required. Repeated treatment is possible after 2 weeks;
- Fitoverm. Does not penetrate plant cells and is harmless to humans. To spray one currant bush, a solution of 1 liter of water and 0.06 ml of suspension is required.
Traditional methods
Folk remedies are used in addition to the main methods of treatment. They are safe for plants and humans. In addition, they are chosen to prevent diseases and the spread of insects.
Traditional methods for treating brown spots on red currants:
- Soap. Add 50 g of soap base to 500 ml of water. It is best to use sulfur or tar soap, which disinfect plants well. They can be added to any natural remedy to make the solution stay on the leaves longer;
- Garlic. For 2 liters of water take 1 cup of chopped garlic cloves. For treatment, the product is used after 2 days, when it is well infused;
- Iodine. A large bucket of water requires 10 drops of iodine. The solution is mixed well and spraying begins.
Methods for treating currants against gall aphids:
- Tobacco dust. For 2 liters of water take 1 glass of tobacco dust. Cook the mixture over low heat for 30 minutes. Then add 2 liters of water and begin processing the currant leaves;
- Mustard. 10 g of mustard powder is added to 1 liter of water. The infusion is left for a day. Before treating the bush, it is filtered;
- Ash. 300 g of wood ash is poured into 2 liters of water. Place the container on the stove and boil for 20 minutes. When the product has cooled, filter it and begin currant treatment.
Agrotechnical measures
Agrotechnical techniques help to increase the effectiveness of treatment. If red leaves are found on the currants, then it is necessary to reconsider the care regimen. Be sure to remove the affected branches, weed the weeds and throw away the fallen leaves. Then they inspect the bush, cut off dry and broken shoots. The branches are cleared of lichen.
During the treatment process, watering and fertilizing are normalized. Currants prefer moderately moist soil. Nitrogen fertilizers and manure are applied in minimal quantities. Particular attention is paid to feeding the bush with potassium and phosphorus compounds. Such substances increase plant immunity and make treatment more effective.
Causes and treatment of white spots on currant leaves
White spots on blackcurrants cause the diseases powdery mildew and septoria. The infection spreads at high humidity and in dense plantings. The first signs appear on young shoots and leaves in the form of a white coating. Gradually it becomes brown. Black currants often suffer from such diseases.
Powdery mildew and septoria reduce currant yields by 50% or more. With severe infection, shoot growth stops and leaves fall off prematurely. If treatment is not started, the bush will die in 2-3 years.
White spots on blackcurrant branches may be caused by lichen. To combat it, sanitization is carried out. In case of serious damage, the shoots are completely removed. The lichen is cleaned manually using a stiff sponge or brush. The barrel is treated with a solution of soap and ash.
To treat bushes, chemical or biological preparations are chosen. The first group includes Bordeaux mixture, Topaz, Abiga-Pik, copper oxychloride. Among biological preparations, Fitosporin, Gamair, Alirin are chosen. The frequency of spraying is no more than once every 10-14 days, depending on the toxicity of the drug.
Preventive actions
To prevent burgundy spots from appearing on currant leaves, agricultural practices are followed in the garden. In autumn, the soil is cleared of fallen leaves. Pest larvae and fungal spores overwinter in them. Then they dig up the soil under the bushes.
For planting, select varieties that are resistant to fungal diseases and pests. Black currants Zabava, Karachinskaya, Lazy, Gulliver, Otradnaya, Minusinskaya, Pygmy have high immunity. Among the varieties with white and red berries, the varieties chosen are Vika, Ogni Ural, Gazelle, Viksne, Marmeladnitsa.
Often fungal spores and pest larvae end up in areas with planting material. Therefore, currant seedlings are taken from trusted suppliers. For disinfection, use a solution of the drug Fitosporin.
Currants are pruned annually to avoid thickening. Select 5 - 7 strong shoots, the rest are cut off at the root. Plants with a strong odor are planted nearby to repel pests. This includes onions, garlic, chamomile, and marigolds.
Good prevention is regular spraying of bushes. To avoid the appearance of red spots on the leaves, currants are sprayed in spring and autumn. Use chemical or folk remedies.
The following drugs are suitable for the prevention of red spots on currants:
- Drug 30 Plus. Provides protection of currants from wintering pests. For processing, choose the period after leaf fall or early spring. Add 500 ml of suspension to 10 liters of water. The treatment is carried out when the air temperature warms up to +4 °C. The solution consumption per bush is 2 liters.
- Nitrafen. The drug destroys aphid larvae overwintering in the soil. For processing, prepare a solution containing 300 g of the substance per large bucket of water.
Conclusion
Brown spots on currant leaves can be treated in different ways. First, the cause of the lesion is determined. Then the appropriate treatment method is selected. Be sure to take into account the time of year and the stage of currant vegetation.
