Almost every gardener grows a currant in the country. It is loved for its generous berry harvest, rich in vitamin C, even from a small bush. Sometimes the result is spoiled by pests and plant diseases. The growth of young shoots of currants decreases, the berries lose their sweetness and become more acidic, the yield drops, and red spots appear on the leaves.
Causes of red spots on currants
Various diseases and insect pests can provoke the appearance of red spots on currant leaves. Timely treatment will help save the plant and preserve the harvest.
Anthracnose: a fungal disease
The causative agent is the fungus Colletotrichum orbiculare. Spores are carried by animals and insects, spread by wind and rain. The fungus especially loves warm and humid weather, so it begins to multiply in July, and the peak of development occurs at the end of summer. The risk of infection is high in currant bushes growing on acidic soil, with a lack of potassium and phosphorus.
The first symptoms of anthracnose appear on the lower leaves of the plant. Single small spots from dark red to brownish brown merge over time into one large spot. The currant leaf rolls up, dries up and falls off.
If the disease is started, the fungus will spread to the entire bush, including young shoots and fruits. The trunk will become dry and brittle, the foliage will fall off. As a result, the plant dies. The mushroom is not afraid of frost. It hibernates on fallen leaves, and with the arrival of warmth, it begins to spread again. Currants are not immune to anthracnose.
Rust
Another type of fungal disease of currants is goblet and columnar rust. All types of sedge are the culprit for the infection of goblet rust, because it is on this weed that the fungus hibernates and develops, and the columnar one - pine and cedar.
Spores tolerate winter well, only frost and even a small layer of snow are destructive for them. In spring they are carried by the wind, infecting currants within a radius of 300 m. If the spring is dry and cool, then the risk of infection of shrubs is minimized, because the fungus loves humid and warm weather.
The incubation period for rust is 10 days. Therefore, the first symptoms of currant infection can be seen only at the beginning of June. Bright orange-red bubbles appear on the upper side of the leaves. As they grow, the leaves turn yellow and fall off. The same fate befell the berries.
By the middle of summer, the underside of the leaves becomes fluffy - thin columns with spores have formed from yellow goblet-shaped pads, which, when ripening, are carried by the wind and fall on sedge for wintering.
Currants are very sensitive to this disease and cannot resist it. In advanced cases, rust affects the bush completely, it does not have the strength to endure the winter, and the currant completely dies.
Red-gall aphid
When planting currant bushes, it should be borne in mind that these pests live in places where herbs such as sage, mint, oregano, lavender and thyme grow. The red-gall aphid is an insect up to 2 mm long, painted in a light yellow color. The ovoid body has short hairs.
Aphids multiply rapidly. From May to October, it makes cracks in the bark, laying eggs. After a short time, offspring appear. During the season, one aphid produces about 100 similar individuals. Female aphids have wings, so they can spread to all bushes.
The red-gall aphid pierces the leaves and sucks the juice out of them. Due to the differences in the structure of the leaf plate (they are softer), preference is given to red, white and other types of currants, and not black and golden.
Ugly tubercles and swellings appear on the surface of damaged leaves. The picture is similar to fungal diseases, but pests are visible on the underside of the leaf. The currant is trying to heal the puncture sites, so a growth is formed in their place - a gall.
As a result of the life and actions of aphids, the leaves are deformed, the plant may die. Another nuisance associated with the appearance of these pests on the currants is a viral infection. When aphids are destroyed, the virus remains inside the plant and it needs to be treated and processed.
In the video presented, the honored gardener shows what a red-gall aphid looks like and talks about methods of dealing with this pest:
How to treat currants?
If the currant bush is only slightly affected, you can try folk remedies. In the case when the disease has completely captured the plant, chemical treatment will help. In severe forms of damage to currants with fungal diseases and red-gall aphids, it is advisable not to process the plant, but to uproot and burn it.
To combat red spots on currant leaves, the entire bush is processed - on both sides, leaves, stems and shoots to the very root. The fallen leaves must be collected and burned. Spraying is carried out in clear weather 3-4 times per season: in the spring, when the leaves are just beginning to bloom, when flower buds appear and before the berries are set.
Folk remedies
The most common folk remedies for anthracnose and rust are:
- Soap solution. Dissolve 400 g of grated laundry soap in 500 ml of water. Rinse all leaves and stems.
- Garlic tincture.Mix 1 cup of minced garlic with 2 liters of warm water. Let it brew for 2-3 days. Strain and drizzle over the currants.
- Soap-garlic mixture.Mix 1: 1 soapy water and garlic tincture. Add 1 tbsp. l. hot pepper and a little of any liquid soap. Spray the bushes.
- Iodine solution. Add 10 drops of iodine to 10 liters of water at room temperature. Treat shrubs.
To destroy aphids, use:
- Tobacco tincture. Dissolve half a glass of tobacco dust in 1 liter of water. Simmer for 30 minutes. Bring the resulting volume to a liter, diluted with water, and put in a cool dark place for a day. Strain through cheesecloth. Add 1 teaspoon liquid soap and 15 g of crushed laundry soap.
- Onion-tomato infusion. Pour 0.5 kg of onion husks with 2 liters of boiling water. After 2 days, add 2 liters of water and some liquid soap. In another container, pour 2 kg of tomato tops with 5 liters of boiling water, leave for 2 hours. Put on low heat and simmer for 3 hours. Strain, add 1/3 of the water. Mix the infusions in a 1: 1 ratio and sprinkle the currants.
- Mustard infusion. Add 10 g of white mustard powder to 1 liter of water. Strain after a day. Spray the plants by diluting 1 cup of this infusion with a liter of water.
- Infusion of marigolds. Pour 10 liters of boiling water over half a bucket of dried flowers. Let it brew for 2 days. Add 50 g of grated laundry soap and mix well.
- Soap-ash composition. Dissolve 1/5 of a bar of laundry soap in 3 liters of water and leave for a day. Pour 300 g of ash with 2 liters of water and boil for 20 minutes. Strain. Mix the resulting solutions by adding 5-7 liters of water.
The gardener shares his folk method of dealing with aphids in the video below:
Some gardeners, instead of spraying with solutions, use sprinkling of currant bushes with tobacco dust and ash. But this method is less efficient for several reasons:
- It is impossible to process the lower part of the leaves.
- The dry matter reaches the plant partially.
- Soaps in solutions add stickiness to them. Thus, the mixture is much longer on the surface of the plant, forming a film on it and providing a positive therapeutic effect.
- By spraying, the bush is treated from all sides, including the lower part of the leaf plates.
If folk remedies do not help, you should try treatment with biologicals. They are safe to work with, so no protective clothing and respirator are required. Biotlin, Fitoverm, and others are effective.
Chemicals
In the absence of a positive result after processing currants with folk remedies to combat diseases and pests, or with a severe degree of infection of the bushes, the use of chemicals is required.
When there are already berries on the bushes, chemical treatment is extremely undesirable, because the berries absorb chemistry and accumulate it inside themselves.
To combat anthracnose and rust, use:
- Copper sulfate 1% and Bordeaux 1% liquid;
- "Agrolekar";
- "PropiPlus";
- Chistoflor;
- "Forecast";
- "Previkur";
- Topsin.
When aphids are damaged, apply:
- Aliot;
- "Calypso";
- Actellik;
- "Confidor";
- "Vofatox".
To destroy the eggs of aphids laid in the bark of shrubs, drugs are used:
- "Decis";
- Aktaru;
- "Insector";
- "Spark";
- Inta-Vir.
Dilution of these funds and preparations for processing currants should be strictly in accordance with the instructions for use. Currant spraying is carried out in calm clear weather with the obligatory use of personal protective equipment.
If it rains after spraying the beds, then the currant treatment should be repeated.
Preventive measures
Autumn prevention
It is carried out after harvest to prepare plants for wintering and to prevent re-infestation of currants in the future. The following measures are characteristic:
- Fallen leaves must be raked and burned, and the soil under the bush must be treated with one of the fungicidal compounds.
- Perform sanitary and anti-aging pruning. To do this, cut off dry and old branches of the bush with the help of a pruner, leaving young shoots forming a crown. This is necessary so that after rain and watering the bush dries out more quickly, and the spores that fall on it do not ripen. Treat all sections with garden pitch.
- Loosen the soil under the bush.
- Feed with the required amount of potassium and phosphorus.
- After harvesting, treat the bushes with a potassium salt solution.
- Do not plant plants close to each other.
- If the currants are growing in a damp lowland or shade, it is best to transplant them into an open area.
We recommend reading our article on how to care for currant bushes in the fall.
Spring prevention
Spring preventive measures are no less important than autumn ones, especially if diseases or pests were observed in the last season. All actions will be aimed at obtaining a healthy harvest.
In the spring you should do:
- Before budding, the bushes and the soil under them are treated with a solution of copper sulfate.
- Feed the currants with a manganese sulfate solution by spraying it on the leaves.
- Pick off affected leaves and burn them.
- Get rid of the weeds.
- Clear the area where the currants are to be exposed to sunlight.
- Treat bushes with pesticides from gall aphids after the leaves appear, but before the flowers form.
- The right choice of plant varieties. Each variety has its own strengths and weaknesses in terms of resistance and susceptibility to certain diseases. Read about currant varieties here.
- Plant near the currant plants that smell repels aphids. It can be onions, garlic, calendula, chamomile.
- Sow meadow grasses next to currant bushes to attract aphid-eating insects, such as ladybugs, bees, and golden hairs, to the site.
- Make sure that there are no anthills near the bushes, as ants are carriers of aphids.
- Thin out currant bush periodically.
By adhering to the recommendations in the prevention of diseases and pests, you will minimize the risk of red spots on currants. These measures will save you the trouble of healing your plants and increase your chances of a bountiful and rewarding crop.