Red spots on currant leaves
The appearance on the bushes of currants in your garden of various kinds of red, brownish, brown spots is a serious symptom indicating that the plants are suffering from some kind of disease, or that pests have attacked. In any case, these signals cannot be ignored, currants clearly need more attention and help. If you do not establish the cause of the lesion and do not take the necessary measures in time, the currants may remain without leaves, which will lead to a decrease in the yield of berries. Shoots of the first year of life may also suffer, which will be a consequence of a decrease in the number of berries harvested in the next season. Bushes affected by infections and pests do not survive the winter well, so red spots on currant leaves are an alarming signal.
Why do red spots appear on currant leaves
Let's figure out what are the main reasons why an amateur gardener can find red spots on currant leaves. There are three such reasons.
- The first signs of anthracnose infection of currants appear.
- Your bushes are dominated by a red-gall aphid.
- Symptoms of goblet or columnar rust have appeared.
In order to determine exactly what kind of misfortune struck the berry dear to our hearts, it is necessary not only to carefully examine the leaves, but also to subject the entire bush to a close analysis. Other unpleasant symptoms may be found.
Let's dwell on each of the above reasons in more detail.
Red spots on currant leaves as a sign of anthracnose
It is possible that red spots on currant leaves are signs of the first stage in the development of mycotic lesions by the fungus Colletotrichum, which leads to the appearance of anthracnose.
In black currant, this disease manifests itself, as a rule, on the leaves. On the upper surface of the leaf, medium-sized, brownish spots are formed, having dark tubercles in the middle, surrounded by violet-brown rims.
Gradually, these red spots become more and more and eventually turn into one continuous spot. As a result, the passage of juice inside the leaf becomes impossible, which leads to its drying out.
On red currants, signs of leaf disease in the form of red spots are visible on the stalks, petioles, and on the berries themselves.
The prerequisites for the onset of this disease include:
- lack of nutrients in the soil (especially potassium and phosphorus);
- not well-groomed bush: poor ventilation, failure to carry out timely sanitary pruning;
- the presence of uncleaned plant residues near the bushes;
- weather conditions favorable for the spread of fungal spores: wind, high humidity combined with high air temperature.
When the first symptoms of anthracnose are found, it is necessary to destroy the affected parts of the bush (if the spread of the disease has not yet reached a critical value). And also to carry out treatment with special drugs that can stop the development of infection.
Processing should be carried out twice - immediately after the first signs of the disease are detected, and then in the fall, after the leaves fall.
Currants have been attacked by this aphid if you see ugly red, yellowish or slightly brownish swellings on the outside of the leaf, and small green-yellow insects on the back.
It should be noted that the red-gall aphid prefers to feed on the juices of red or white currants. But black and golden suffer from this pest much less often. This is due to the fact that the leaves of red and white currants are much softer and, accordingly, easier to gnaw.
If the spread of aphids reaches a mass character, the bush can suffer quite badly, up to complete drying out. Therefore, having noticed the first signs of the presence of red-gall aphids on their landings, you should immediately take the necessary measures.
If only a few leaves are affected, they can simply be plucked and burned somewhere away from the garden. But if there are already much more affected areas, you will have to do something more radical.
There are plenty of options. You can use both old folk methods and various kinds of modern means of industrial production. Both chemical and biological.
Goblet and columnar rust
Red spots on currant leaves: photo of the disease
Goblet rust is a fungal disease that manifests itself to a greater extent on red and white currants during flowering. At the onset of the disease, reddish spots appear on the outside of the leaves. This produces brownish seals on the underside.
Over time, a kind of columns with hanging fungal spores grow from these seals.
Columnar rust makes itself felt by the end of summer. The symptoms of this fungal disease are also "rusty" seals appearing on the inner surface of the leaves. Their characteristic feature is that if they are touched, then powder will remain on the hands.
At the same time, spots of a yellow tint can be seen on the outside of the sheet.
Both types of rust are quite serious diseases for plants. They can significantly reduce the amount of berries harvested from the bush. And also negatively affect the development of the shoots of the first year of life, which will also lead to a decrease in yield in subsequent seasons.
Factors contributing to the development of these infections are the location of plantings of currants in low wetlands, as well as too close proximity to conifers or sedge.
Red spots on lsith currants: how to treat and how to treat?
You need to start acting already when the first symptoms of currant infection appear. And even better if before they appear.
They significantly reduce the risk of developing certain diseases, as well as attacks of all kinds of pests, preventive treatment of shrubs with both biological and folk remedies, adherence to basic agricultural techniques, timely cleaning of various kinds of organic residues.
Red spots on currant leaves and the use of chemicals
Chemical preparations differ in the presence of the main active substance in them, as well as in the form of action on parasites (or disease). If we talk about the means used against pests, then the following mechanisms of exposure to a toxic substance are distinguished:
- respiratory - have a detrimental effect on the respiratory system of pests;
- intestinal (pyrethroid) - affect the digestive system of parasites through treated plants;
- contact - cause the death of the parasite by direct contact with the active substance;
- systemic - also cause the death of the pest when absorbed by the treated plants. These funds are able to combine the signs of belonging to several groups at once.
Actellic. The drug of the intestinal and contact group. The active ingredient is pirimiphos-methyl. Effective against aphids, gall midges and other parasites.It can be easily used on the back of the leaves, where, as a rule, the main forces of the enemy are concentrated.
Sick bushes are sprayed with a solution of the drug prepared according to the instructions. They also process the planting material before planting in the ground. In this case, a 0.3% solution is used, placing the planting material in it for 2 minutes.
The action of Actellik occurs in the interval from 5 minutes to 3 hours, depending on the weather, as well as the type of parasite. This remedy can protect the plant for up to three weeks.
The following negative points should be borne in mind when using this drug:
- in the case of frequent use, it can cause resistance to some pests;
- can not be used as a prophylaxis;
- dangerous for bees and some other insects.
Inta-vir. It belongs to the pyrethroid group of agents, it causes paralysis in insects that have come into contact with it when eating the treated plant.
The working solution is obtained by diluting 8 g of the product in a bucket of water. The currants are treated by spraying the leaves at the rate of 2-3 liters of working solution per bush. Processing can be done twice.
This drug does not have a negative effect on humans and animals, does not have a strong chemical odor, and can be used in combination with other chemicals.
The onset of Inta-vira exposure is from half an hour to a day, and the protection period is approximately 2 weeks.
Pay attention to the following disadvantages of this drug:
- not effective against pests that have not yet hatched or are in a state of suspended animation;
- it makes no sense to apply in rainy weather;
- dangerous for bees and some other insects.
Confidor. The active ingredient is imidacloprid. The drug is systemic, harmful to the nervous system of pests. The solution of the drug prepared according to the instructions is carried out both by spraying the affected bushes and by prophylactic treatment of the planting material. It is also used for processing the soil directly.
This drug is not washed off with water, which makes it possible to use it at the same time with watering, dressing, or in rainy weather. Does not lose its effectiveness at high air temperatures, does not cause resistance, does not accumulate in berries.
It is able to protect the plant for 35 days (which is a very high indicator). However, it has a negative effect on bees and other pollinating insects.
Calypso. Systemic remedy. Causes the death of parasites through direct contact with it, as well as when they eat processed leaves. The active ingredient is thiacloprid. Treatment with this tool can be carried out quite often (up to 4 times during the summer-autumn period).
Calypso has a positive effect on the yield of currants, is able to protect the bush for a month, does not have a negative effect on bees (if the instructions are followed). It begins to act within half an hour or an hour after application.
Among the negative qualities of this remedy are:
- the need to use individual respiratory protection when working with it;
- impossibility of simultaneous use with other chemicals for pest control;
- the need for strict control over the use of the drug. In no case should he get into drinking water sources, or into animal feed.
Kinmix... Refers to the contact-intestinal group of funds. The active ingredient is beta-cypermethrin. This remedy is effective even on eggs and pest larvae. Does not accumulate in berries. It takes effect one hour after treatment, and the duration of protection is from 14 to 25 days.
Consider the following negative points when using this tool:
- dangerous for bees and some other insects;
- if the dose of the drug indicated in the instructions is not observed, it can cause a burn on the leaves of the bush;
- washed off with water (should not be used in the rain, you can repeat the treatment if the currants are still wet).
Aliot. Refers to the contact-intestinal group. The active ingredient is malathion (karbofos). It is effective both against mature pests and against their larvae and eggs. It is advisable to use this remedy in the spring. Use up to 1 liter of solution for each bush.
The weaknesses of this drug are the inability to act in rainy weather, the danger to insects pollinating currants.
However, it is effective in treating bushes in the early stages of the disease, therefore it should be used when the very first symptoms are detected. The processing of the bushes is carried out twice during the autumn-summer period (but no more, otherwise addiction will arise).
Please note that the foundation is not used for cultivating the land, this may negatively affect the state of the plantings.
Acidan. Contact-systemic drug. Based on the work of two active ingredients: mancozeb and metaloxyl. It has both a preventive effect and fights against fungal diseases in the early stages of the disease.
Does not cause resistance, can be used in rainy weather. It has a beneficial effect on the processes of oxygen production in plants. The ability to protect plantings lasts for 2 weeks. Among the disadvantages, the toxicity of the agent for bees and other insects can be noted.
Topsin-m... Contact-systemic drug, acts both against fungal diseases and against parasites. Destroys not only adult insects, but larvae and eggs. The death of pests occurs from direct contact with a toxic substance, as well as when eating processed parts of the plant.
In addition, the product is also suitable for prophylactic treatments. The active ingredient is thiofonate methyl. It is able to stop the multiplication of the fungus during the first days after application. Planting processing must be carried out twice a season (but no more, because it is addictive).
The drug is used in the form of a solution for spraying, as well as a means for processing planting material and soil treatment (which will help protect plants from pests entering the plant from the soil). It should be noted that the agent is not phytotoxic, not dangerous for pollinating insects, it can be used in combination with other chemicals.
Fitoferm. Contact-intestinal preparation, active ingredient - aversectin. Works especially effectively on black currants. Does not cause addiction, does not lose effectiveness even at high air temperatures (while at temperatures above + 20 ° C, its toxic properties are reduced). Not suitable for complex use with other chemicals.
Biotlin. Refers to the contact-intestinal group of funds. The active ingredient is imidacloprid. The main area of application is the fight against red gall aphids. At the same time, the agent successfully prevents further pest reproduction. Suitable for processing the inner surfaces of leaves, where the greatest number of pests are located.
To prepare a working solution, take 3 g of the drug in a bucket of water. The treatment is carried out based on the consumption of a solution of 1-1.5 liters per bush (depending on the degree of infection). The duration of action of Biotlin is 21 days.
Agravertine. A biological preparation, the action of which is based on an extract from soil fungus strains (the active ingredient is avertin). The product does not pose a threat to bees, does not affect the safety of the crop, and can be used as needed, since it does not cause resistance.
When working with the tool, you must take into account the following negative points:
- cannot be used simultaneously with other chemicals;
- low efficiency at high air temperatures (above + 18 ° С);
- does not work in rainy weather.
Solving the problem with folk remedies
If the defeat of the currant has not reached a critical level, or if, for example, the infection occurred during a period when the use of chemicals is impossible (say, during the ripening of berries), you can try using old remedies to combat currant ailments.
Infusion of marigolds. It is used to combat red-gall aphids. To prepare the infusion, take 500 g of crushed marigold flowers, add a bucket of water. The mixture is boiled, and then tightly closed and left to infuse in a dark place for three days.
Then soap is added to the mixture (you can use both grated laundry soap and liquid soap, including antibacterial ones), filter. The resulting infusion is used to treat the lower surface of the leaves.
Infusion of tomato tops. Effective against aphids. To prepare the infusion, take 3 kg of chopped tomato tops (you can also use dried tops, while reducing its amount to 1 kg), add a bucket of water and boil for half an hour.
Then remove from the stove and let it brew for 3-4 hours. After that, the infusion is filtered, diluted with water based on a ratio of 1: 4, about 35 g of soap is added (so that the agent lingers on the surface of the leaves longer).
The resulting product is used to treat the bushes, repeating the treatment as necessary with an interval of 5-7 days (excluding the period of flowering currants).
Decoction of tobacco dust... This tool is also used to combat various pests. To prepare it, take about half a glass of tobacco dust and 1 liter of water. The solution is boiled for half an hour, constantly bringing the volume of liquid to the original level. Then remove from heat and leave in the dark to infuse for 1 day.
Soap is added to the finished broth, and the product is ready to use.
Laundry soap. It can also be used as a completely independent agent in the fight against aphids and other parasites. For its use, 300 g of grated 72% laundry soap is diluted in 2 liters of warm water.
After dissolution, the volume of the liquid is increased to 10 liters by adding water. To enhance the effect, ash, tobacco dust, soda, vegetable oil can be added to the solution.
Mustard powder. Works against aphids and other pests. The remedy can be prepared in different ways:
- In a bucket of water, mix 100 g of mustard powder and the same amount of salt (you can iodized). Apply the resulting product once.
- To 10 liters of warm water add 20 g of mustard powder and 1 tbsp. l. 70% vinegar (if you take 9% vinegar, then the proportion will change to 75 g of mustard and 75 g of vinegar). The resulting product can be used to process plantings with a frequency of 1 time per 7 days.
Hot pepper infusion. It works both against parasites and against fungal diseases of the currant. Prepare as follows: 25 g of ground hot pepper is poured with half a liter of boiling water and left to infuse for 4 hours. Soap is added to the resulting infusion and the planting is treated.
For the preparation of the infusion, you can also use fresh hot pepper. To do this, add water to a whole jar of pepper pods (0.5 l volume) and bring to a boil, and then infuse for 2-3 days. The treatment is carried out in advance by diluting with infusion with water (a bucket of water per glass of solution) and adding soap.