Diseases of red and black currant: red spots on the leaves

Currant, like any culture, can suffer from diseases and pests. Most often, the lesion has the appearance of red or white spots. If you do not take action in time, you can lose the crop 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 preparations.

Why do currants have red leaves

Currant is a berry shrub with green leaves. They have 3 to 5 lobes and large teeth. Their leaf plate is smooth and shiny, has a specific smell. When red spots appear, the integrity of the leaves is violated, the plant loses its decorative appearance.

Reasons for the spread of brown or red spots on currants:

• the initial stage of the disease anthracnose;
• the spread of a fungus that causes rust;
• the appearance of a dangerous pest – red-gall aphids.

In autumn, the color of currant leaves becomes yellow or burgundy. Leaf fall ends in September or October, depending on weather conditions. The reddening of the leaves in autumn is 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, a method of treatment is chosen. In order to accurately diagnose why the leaves of the red currant are covered with red spots, they examine the entire shrub.

Antraknoz

Anthracnose is a disease of trees and shrubs caused by a marsupial fungus. It is distributed in Western and Eastern Europe, America, Our Country. At risk are the northern and western regions with a temperate climate and frequent rains.

The defeat extends to all types of culture: black, white and red. Brown spots appear on the petioles and leaves of the currant. Their size is about 1 mm. Then they develop spores in the form of black tubercles. Black depressed spots are observed on petioles.

The harmful fungus remains in the fallen leaves for the winter. Infection begins at the end of May. Diseases are most susceptible to leaves that blossomed 25 – 30 days ago. Anthracnose on currants develops at the end of flowering. If measures are not taken in a timely manner, then the peak of the defeat will be in July and August.

The fungus grows in drops of moisture. The optimum temperature for its development is from +15 to +20 °C. Under these conditions, the incubation period lasts 8-12 days. On blackcurrant, the disease appears at lower temperatures.

When red spots appear, the development of a bush that does not receive the necessary nutrition slows down. If you do not start treatment, its frost resistance will significantly decrease. In the spring, the bush may lose half of the shoots.

gall aphid

The cause of spots on red currants can be gall aphids. In early spring, its larvae appear, which spread through the plants. They have an ovoid body up to 2 mm long and a pale green color. During the season, up to 20 generations of gall aphids are formed.

As a result of the activity of the larvae, the leaves on the tops of the shoots change color and shape. On the currant, red swellings are diagnosed – galls. These are neoplasms that arise as a protective reaction of a plant to a pest.

The gall aphid is widespread in Eurasia. The insect is found in both southern and northern regions. After the appearance of red spots on the leaves, the plants give a small increase 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, which belongs to the fungal group. The first symptoms appear after flowering on shoots and leaves. They look like large rounded spots of yellow or orange. Often these spots have a red border. By mid-July, black dots appear on the leaves – fungal spores.

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 prematurely, the yield of the bush decreases, and the taste of the berries deteriorates.

How to process red leaves on a currant

For the treatment of currants from red spots, chemical or biological preparations 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 processing before fruiting or after harvesting berries.

For the treatment of currants, a solution is prepared. It is sprayed on the leaves with a spray bottle. The bush is processed on a cloudy day or in the evening when the sun disappears. Gloves, goggles or a special suit are worn to protect the skin and organs of vision.

If red convex spots on the leaves on the currant are caused by diseases, then the following remedies are used:

• Bordeaux mixture. Solution based on lime and copper sulfate. Works against various fungi. The agent adheres well to the leaves. For the treatment of red spots on currants, a solution with a concentration of 1% is obtained. Processing is carried out no more than once every 14 days;
• Copper chlorine. An alternative to Bordeaux liquid. It has the appearance of light green crystals. Copper compounds have a detrimental effect on microorganisms. In the treatment of currants, the duration of the solution is 10 – 12 days;
• Abiga Peak. Fungicide intended for the treatment of currant diseases. 10 ml of suspension is added to 40 l of water. The working solution evenly covers the leaves and is not washed off by rain. The agent is effective at low temperatures, promotes the formation of chlorophyll, increases the immunity of plants.

If red blisters on currant leaves were caused by gall aphids, then they resort to insecticides:

• Aktara. Enteric-contact preparation, which is effective at low humidity and high temperature. The solution is not washed off with water. Spraying is carried out before the appearance of buds or after removing the berries. 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;
• Detox. Systemic drug for the control of aphids and other insects. Differs in high efficiency. The pest dies a few hours after the treatment of the bush;
• Iskra. An effective remedy against various insects. Works even in hot weather. Iskra is safe for humans, animals, birds and beneficial insects. 10 ml of suspension are added to 5 l of water. Spraying is carried out with the mass appearance of the pest.

After processing currants from pests, they begin to treat it. Bushes are fed with mineral complexes. In the spring, urea or another nitrogen-based fertilizer is applied. In summer and autumn, a solution is prepared containing superphosphate and potassium sulfate.

Biological preparations

Biological preparations suppress the activity of a harmful fungus. Some of them are used at any stage of bush growth. The active substances do not penetrate into the tissues of the plant, do not accumulate in the fruits

For the treatment of red swollen spots on currant leaves, the following biological preparations are used:

• Tivit Jet. Sulfur-based agent 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;
• Agrodoctor. Systemic fungicide to protect the garden from fungal diseases. Spraying is carried out before the formation of buds or after removing the berries. The consumption rate is 10 ml per large bucket of water;
• Chihom. A new drug that provides treatment and protection of currants from the fungus. Spraying requires 10 ml of fungicide per 10 liters of water. No more than 1 liter of solution is prepared per bush. Processing is carried out in early spring or autumn.

Biological preparations against gall aphid:

• Akarin. Fast acting insecticide. After 8 – 16 hours after treatment, the aphid loses its motor activity and dies. The bush is sprayed during the growing season. For 1 liter of water, 2 ml of suspension is required. Re-treatment is possible after 2 weeks;
• Phytoverm. It does not penetrate into plant cells and is harmless to humans. Spraying one currant bush requires a solution of 1 liter of water and 0,06 ml of suspension.

Folk 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 for the prevention of diseases and the spread of insects.

Folk methods for the treatment of brown spots on red currants:

• Soap. 500 g of soap base are added to 50 ml of water. It is best to use sulfuric or tar soap, which disinfect plants well. They can be added to any natural remedy so that the solution stays on the leaves longer;
• Garlic. For 2 liters of water, take 1 cup of chopped garlic cloves. For treatment, the remedy is used after 2 days, when it is well infused;
• Iodine. A large bucket of water requires 10 drops of iodine. The solution is well mixed and sprayed.

Methods for treating currants from gall aphids:

• Tobacco dust. For 2 liters of water take 1 glass of tobacco dust. Means are boiled for 30 minutes on low heat. Then add 2 liters of water and start processing currant leaves;
• Mustard. 10 g mustard powder is added to 1 liter of water. The infusion is left for a day. Before treating a shrub, it is filtered;
• Ash. 300 g of wood ash is poured into 2 liters of water. The container is placed on the stove and boiled for 20 minutes. When the product has cooled, it is filtered and currant treatment is started.

Agrotechnical measures

Agrotechnical methods help to increase the effectiveness of treatment. If red leaves are found on the currant, then it is necessary to reconsider the care scheme. Be sure to remove the affected branches, weed weeds and discard fallen leaves. Then they inspect the bush, cut dry and broken shoots. Branches are cleaned of lichen.

In the process of treatment, watering and top dressing are normalized. Currant prefers moderately moist soil. Nitrogen fertilizers and manure are applied in minimal quantities. Particular attention is paid to feeding the bush with potash and phosphorus compounds. Such substances increase the immunity of plants and make the treatment more effective.

Causes and treatment of white spots on currant leaves

White spots on blackcurrants cause diseases powdery mildew and septoria. The lesion 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 are more likely to suffer from such diseases.

Powdery mildew and septoria reduce the yield of currants by 50% or more. With a strong infection, the growth of shoots stops, and the leaves fall prematurely. If you do not start treatment, then after 2 – 3 years the bush will die.

White spots on blackcurrant branches can be caused by lichen. Sanitary treatment is carried out to combat it. With a serious defeat, the shoots are completely removed. The lichen is cleaned by hand with a hard washcloth or brush. The trunk is treated with a solution of soap and ash.

For the treatment of bushes, chemical or biological preparations are chosen. The first group includes Bordeaux liquid, Topaz, Abiga-Peak, copper oxychloride. From biological preparations choose Fitosporin, Gamair, Alirin. The frequency of spraying – no more than once every 10 – 14 days, depending on the toxicity of the drug.

Preventive measures

So that burgundy spots do not appear on currant leaves, agricultural practices are observed in the garden. In autumn, the soil is cleared of fallen leaves. Pest larvae and fungal spores hibernate in them. Then they dig the soil under the bushes.

For planting choose varieties that are resistant to fungal diseases and pests. High immunity is blackcurrant Zabava, Karachinskaya, Lazy, Gulliver, Otradnaya, Minusinskaya, Pygmy. Of the varieties with white and red berries, the variety Vika, Lights of the Urals, Gazelle, Viksne, Marmeladnitsa are chosen.

Often, fungal spores and pest larvae enter areas with planting material. Therefore, currant seedlings are taken from trusted suppliers. For disinfection, a solution of Fitosporin is used.

The currants are pruned annually to avoid thickening. Choose 5 – 7 strong shoots, the rest are cut off at the root. Plants with a strong smell are planted nearby, which will scare away pests. This includes onions, garlic, chamomile, 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:

1. Preparation 30 Plus. Provides protection of currants from wintering pests. For processing, choose the period after leaf fall or early spring. 10 ml of suspension is added to 500 l of water. The treatment is carried out when the air temperature warms up to +4 °C. The solution consumption per bush is 2 liters.
2. Nitrafen. The drug destroys aphid larvae wintering in the ground. For processing, prepare a solution containing 300 g of the substance in a large bucket of water.

Conclusion

There are many ways to treat brown spots on currant leaves. First, the cause of the lesion is determined. Then choose the appropriate method of treatment. Be sure to take into account the time of year and the stage of vegetation of the currant.