What are the causes of red, swollen spots on red and black currants?
Appearing spots occur for many reasons, in particular:
- infection by the fungus Colletotrichum leads to anthracnose;
- defeat by red gall aphids;
- overgrowth of caricis Kleb causes rust.
To establish the exact cause of damage to the leaf blade, it is important to conduct a thorough inspection of the entire plant.
What to do if red spots appear on currant leaves - video
Anthracnose - the cause of spots on currants
In black currants, damage to the leaves is most often observed. Dark brown spots form on the outer surface of the leaf.
In the center there are tubercles that can grow to such sizes that they occupy the entire area of the leaf. This significantly interferes with the free movement of juice along the plate itself and leads to wilting.
Photo of currant disease - anthracnose
Unlike black varieties, red currants additionally experience infection of the berries themselves, stalks, and petioles.
The development of anthracosis fungus occurs for several reasons, in particular:
- lack of potassium and phosphorus;
- intense foliage;
- lack of lighting;
- wind;
- the presence of diseased parts on the plant, for example, branches;
- Unsuitable weather conditions such as elevated temperatures and high humidity levels.
The very first procedure for disinfecting and eliminating damaged currant branches with red spots is done immediately after identifying the disease. The next one is carried out after the leaves have fallen.
Red gall aphids are another cause of red spots on currants.
When a shrub is infected with gall aphids, irregularly shaped spots appear that are yellow, brown, or red.
Convex spots can be observed on currant leaves, and small insects can be observed from inside the leaf blade. They feed on plant sap.
Photo of red gall aphids on currants
Effective treatment consists of the use of “traditional folk remedies,” biological preparations, and chemical agents.
Ways to combat gall aphids - video
Rust (columnar and goblet) is the cause of red spots on currants
Refers to fungal diseases.
Columnar rust usually occurs on currants in August.
Photo of columnar rust on currants
Photo of goblet rust on currants
The very first signs of rust on currants:
rust-colored growths on the inside of the leaf.
When you touch them they begin to crumble. Yellow spots appear on the top of the leaf plate. During the flowering period of currants, damage to the goblet form of rust is typical.
The disease can be identified by the fact that there are small yellow-red spots on the surface of the leaf plate, and brown pads underneath. From these formations grow columns on which hanging rust spores are located.
How to get rid of rust on currants - video
[media=
https://youtu.be/HaODb844aZc
]
How to treat the bush?
When choosing chemicals to treat brown spots on the leaves of a currant bush, you need to be extremely careful. Because the shrub is a fruit-bearing shrub, pesticides and other harsh chemicals can be hazardous to humans.
All drugs that protect the bush from harmful insects or infections are divided into groups. Each group is characterized by the main active substance and the method of influencing the problem.
If the leaves are swollen
If the leaves of the bush turn red and swell, then it has been attacked by harmful insects, namely aphids. You need to choose the drug wisely, based on the type of impact of the chemical on the life support systems of pests:
- Respiratory. Affects the respiratory organs of insects.
- System. They penetrate the plant tissues of the bush, eating which the insects die.
- Contact. Pests die only in direct contact with the drug.
- Pyrethroid. They are also called intestinal, since the pests die by eating the treated parts of the bush.
To combat harmful insects, you should use specialized preparations - insecticides. They affect both adults and larvae. Depending on the type of action of the drug, you need to spray the bush with a spray bottle or water it at the root.
Popular drugs:
- Fitoverm. Refers to a mixed type of drug (contact-intestinal). The active substance of the chemical is aversectin. Works in hot weather, toxicity decreases at temperatures of +21 °C and above, does not mix with other products;
- Biotlin. Contact-intestinal solution, the active ingredient of which is imidacloprid. To treat shrubs against aphids, you need to dilute 3 g of the substance in 10 liters of clean water. For each bush you need to pour 1.3-1.5 liters of the prepared solution. Helps destroy insects even in hard-to-reach areas, as well as protect the plant from the spread of new colonies of parasites;
- Agravertine. Bio-based insecticide. The active ingredient is avertin. It does not accumulate in plant tissues or in the soil, is not dangerous for beneficial insects, and can be used many times, since it is not addictive to pests. Do not mix with other insecticides; it does not work well at temperatures of +19 degrees and above.
Turn red and curl
Reddened, dried and curled leaves are a symptom of anthracnose. The fungus most often affects shrubs in July and August.
How to fight:
- The soil and shrubs should be treated with a 1% solution of copper sulfate. This must be done before the leaves appear.
- Before the flowers form, you need to spray the bush with Topsin-M.
- During the formation of ovaries, you need to feed the bush with wood ash.
- To strengthen the plant’s immune system, it is necessary to apply complex fertilizers with nitrogen and boric acid.
- Immediately after the harvest is harvested, you need to treat the bushes with Bordeaux mixture (a mixture of lime and copper sulfate).
- All fallen leaves must be burned to prevent fungal spores from spreading to healthy bushes during the winter.
- In the autumn, immediately after digging the soil, you need to treat the bush with Nitrophen.
Preventive measures
In order to prevent the appearance of red spots on currants, it is necessary to do prevention. It varies depending on the seasons.
Autumn prevention of currants from the appearance of red spots
All dry, already fallen leaves should be burned. The mulch can be transferred to the compost heap. The soil must be dug up and well loosened. It is important to systematically carry out pruning:
remove dried branches, thin out the thickened crown. The cut areas are treated with garden varnish to avoid infection.
Gall aphids are eliminated with garlic and onion solutions. Fungicides containing copper are very good as sprays. When the leaves have already fallen, the currants are sprayed with a 3% solution of Bordeaux mixture. Everything is processed:
both the branches and the ground under the currant bush.
Spring prevention of currant bushes from red and brown spots on the foliage
Red spots that appear on currant leaves in the spring indicate that autumn prevention with pesticides must be repeated, subject to certain deadlines.
Spraying currants against anthracnose should be done before the buds open.
Currant plants should be sprayed against gall aphids when the leaves appear, before flowering. According to the autumn scheme, treatment with Bordeaux mixture is repeated.
Summer prevention of currants from pests and diseases
If there are ovaries, it is no longer possible to treat currants with special means.
It's worth waiting for the harvest.
Be sure to clean up damaged foliage. You can carry out the treatment using folk remedies such as garlic, dandelions, onions, and laundry soap.
A very good remedy that helps eliminate red spots on currants is to plant herbs that will attract ladybugs, lacewings and other insects that destroy pests. It is recommended to plant plants that attract such insects.
Loosening the soil helps a lot.
In general, good and timely care for currants is enough to prevent red spots from appearing.
Interesting article:
How to prune raspberries in spring, autumn, summer
Traditional methods
If currants are affected by anthracnose, then folk remedies will not help. The disease is considered one of the most severe, so it needs to be combated only by chemical treatment. But you can easily get rid of aphids in several proven ways:
- infusion of marigolds. Dried flowers are crushed, to prepare the solution, fill a bucket with them to about half the total volume and fill it with hot water. Crumble 100 g of laundry soap into it and stir. When the mixture has cooled, it is sprayed on the bushes in the morning once a week for once a week. The number of treatments can reach 3-4 times;
- infusion of onion with tops. Tomato tops (about 2 kg) are poured into a bucket with 5 liters of boiling water. When the mixture has cooled slightly, it is passed through cheesecloth and diluted with clean water in a ratio of 1:2. In another container, onion skins removed from 5 large heads are poured with boiling water, left to cool and filtered. Mix the solutions, grate 50 g of soap and irrigate the bushes with the mixture once every 10 days;
On a note! Laundry soap can be added to any solution. After spraying, the product will stick better to the branches, and the soap mixture will form an invisible protective film.
- decoction of tobacco dust. Per liter of water you will need 100 g of tobacco dust. Mix the ingredients and boil for at least 30 minutes. Add a glass of water to the contents and cool. The broth is filtered, shavings of laundry soap (2-3 tbsp) are added, and the plants are sprayed. This method is suitable even for fruit-bearing bushes;
- mustard powder. Dilute tbsp in a liter of water. mustard powder. Then take 200 ml from the concentrate and add enough water to make a liter of solution. Pour it into a spray bottle and treat the currants once every 7-10 days;
- red pepper infusion. Aphids do not add a bitter taste, so when treated with pepper solution, they stop attacking the leaves of the bush. You need to grind a kilogram of red pepper, add 10 liters of water and boil the mixture for 3 hours. Then the broth should brew for a couple of days, after which it is diluted again with water 10 times and the currants are processed.
Any treatment with folk remedies should be carried out at intervals of 7-10 days and at least 2 times. Choose dry, windless weather and irrigate the entire above-ground part of the bush, paying attention to the lower leaf surface. Although folk remedies are safe for humans and culture, they will help cope only when the affected area is small. In other cases, you only need to act in radical ways: chemicals and insecticides.
Gardening tips for getting a good currant harvest
Some practical tips from gardeners for preserving and obtaining a healthy harvest:
- To get a guaranteed harvest, you need to plant several varieties of currants with different growing seasons on your plot. Even if frosts appear in spring, there will be a harvest in any case.
- When sufficient distance is maintained between the bushes, currants will produce a good harvest in any case. The optimal distance is 2 meters. If the area is limited, it is necessary in any case to maintain an interval of at least 1 meter. When plantings are located too close to each other, the lifespan of the bushes becomes significantly shorter and the yield decreases accordingly.
- It is worth maintaining a distance from the fence (from 1.2 to 1.5 meters).
Land with a high level of acidity requires the addition of lime.
The depth of the cervix is approximately 8–10 cm.
Gradually, the currant root system will grow, which will lead to a healthy state of the entire plant.
It is necessary to properly fertilize the currant bushes by first making several holes in a circle near the trunk, into which to pour the solution with fertilizer.
Non-communicable diseases
The manifestation of such pathologies is associated with improper care, nutrient deficiency, and excess content of any element in the soil.
Marginal necrosis
The cause of this pathology is excessive chlorine content in the soil. A gray border appears on the leaf blades of the crop, which gradually dries out and falls off. The boundary between healthy and diseased tissue is sharp, which distinguishes necrosis from similar signs of potassium deficiency.
The disease usually appears in August, although the border may appear in mid-summer. For treatment, fertilizing is carried out with a solution of ammonium nitrate. Affected shoots with leaves are cut off and burned.
Withering
In dry and hot summers, currant leaves wilt. If there are no visible signs of damage or the presence of pests, then most likely the bushes are suffering from a lack of moisture.
The problem is solved simply: provide the crop with timely watering, while avoiding waterlogging of the soil. It is recommended to mulch the soil around the berry gardens with grass and compost.
Change in leaf color
Lack of iron and magnesium are the causes of discoloration of leaf plates.
Signs:
- with magnesium deficiency, the leaf blade turns yellow, while the veins remain bright green;
- Lack of iron is manifested by complete yellowing of the leaves.
To compensate for the deficiency of microelements, in the first case, currants are fed with solutions of potassium sulfate (30 grams per bucket of water), or potassium magnesium.
The composition of chelated iron will help eliminate iron deficiency. Proportions: dilute 5 grams of product in a bucket of water and spray on the leaves.
