Content
Anthracnose of grapes is a dangerous fungal disease that affects many varieties and leads to a decrease in yield, developmental delays, and in advanced cases, the death of the bush. The pest quickly attacks the above-ground part of the plant and is active in relatively warm and rainy weather. Therefore, for prevention, it is necessary to observe the watering norm, as well as inspect the bushes and carry out treatments using special preparations.
The causative agent of grape anthracnose
Anthracnose (also spotted anthracnose) is an infectious disease caused by the fungus Gloeosporium ampelophagum Sacc. Not only grapes are affected, but also other crops - most often currants, peas, tomatoes, apple trees, flax, and cherries.
Microscopic fungi overwinter on the affected organs of grapes in the form of sclerotia, mycelium and pycnidia. They tolerate unfavorable environmental conditions well and reproduce effectively (each mushroom produces up to 30 generations of spores). Direct germination begins only under certain conditions:
- presence of water drops;
- temperature above 10 degrees Celsius;
- absence of intense heat (no more than 40 degrees).
The main methods of transmission of the grape anthracnose pathogen:
- seeds;
- the soil;
- foliage, branches and other plant remains.
First symptoms
The causative agent of anthracnose can quite quickly infect the entire above-ground part of the grapes - stems, shoots, foliage, fruits. The main signs appear already in the spring, if at this time it rains often and heavy dew falls. The first symptoms of grape anthracnose are noticeable on young shoots. Brown spots of round or angular shape appear on the leaves, surrounded by a border of a dark or reddish hue. Over time, they merge and become larger. At the site of the spots, plant tissues dry out and die. Holes are formed.
Due to anthracnose, grape leaves become massively holey.
Subsequently, new signs appear:
- oval brown-brown depressed spots on shoots;
- cracking of the surface of branches;
- deep ulcers;
- drying out and death of the vine;
- brown formations on the surface of the petals;
- shedding of flowers;
- withering and death of brushes;
- dots with a dark border on the berries.
The second wave occurs in August and September. The extent of anthracnose development depends on the weather. If it rains a lot, the situation is noticeably worse.
Causes
Grape anthracnose is an infection, so its occurrence cannot be 100% excluded. At the same time, it is possible and necessary to prevent the main causes of occurrence. The transmission of anthracnose fungi is facilitated by:
- deficiency of phosphorus and potassium in the soil;
- many insects (though they themselves do not suffer from spores);
- low pH (i.e. increased soil acidity);
- windy and rainy weather;
- Excessive watering and lack of constant air flow to the grape bushes may be a provoking factor.
How to deal with grape anthracnose
Methods for treating such a dangerous grape disease as anthracnose must be quite effective and applied systematically. Gardeners try to use folk remedies and biological preparations. They are relatively safe for the grapes themselves and other plants, as well as for humans, beneficial insects and animals. But if the disease is advanced, chemicals are used. The most effective remedies are described below.
Chemicals are most often used to combat infection.
Folk remedies
Folk remedies are effective only at the early stage of infection. They are used in several cases:
- preventive treatment in early spring;
- spraying when the first symptoms appear;
- treatment of grape anthracnose during berry ripening.
The main recipes are:
- Place the hay on the ground so that it rots, then pour it into a container (up to a third of the volume) and fill it with water. Wait a week. Strain and apply the resulting infusion to the vineyard several times after rain with an interval of 10-15 days.
- Grind a few garlic cloves (100 g) and leave in 10 liters of hot water. A day later, add 50 g of laundry soap shavings, 2 tbsp. l. salt and 50 ml of potassium permanganate or ferrous sulfate (in both cases, the solution concentration is 1%).
- Baking soda solution (sodium bicarbonate) – 200 g per 1 liter. You can add 2-3 tablespoons of laundry soap shavings or liquid detergent.
- Whey, kefir or yogurt - 1 liter per 10 liters of cold water. You can also add a little soap to this solution.
It is important to understand that folk remedies, although safe, are low in effectiveness. Therefore, if the disease has already begun to develop, it is better to use chemical or biological fungicides. Otherwise, you may miss time, and then some of the grapes will die.
Biological preparations against grape anthracnose
Biological preparations contain strains of microorganisms. They effectively destroy spores, mycelium and other parts of fungi. They are used both for the prevention and treatment of grape anthracnose. Popular biofungicides include:
- "Fitosporin M" is a safe drug that strengthens the immunity of grapes and many other crops. It is used in a dosage of 5-10 g per 10 liters of water.
- "Alirin B" is used to destroy the pathogen of grape anthracnose in the soil. Can be used individually and together with other biofungicides, but not in combination with chemicals.
- "Trichodermin" is a safe drug that is used in an amount of 200 ml of liquid per 10 liters.
"Fitosporin M" is one of the best biological agents with universal action
Fungicides
Modern chemicals that can be used to treat grape anthracnose include:
- "Abiga-Pik" is a drug against anthracnose containing copper oxychloride. Use in an amount of 50 g of suspension per 1 liter.
- "Fundazol" is a systemic fungicide for the treatment of anthracnose.Used for watering the soil and cultivating the above-ground parts of grapes.
- "Poliram" is a powerful contact fungicide that is used no more than four times a year. 5-10 g of powder are dissolved in 10 liters of water.
You can use the following drugs: “Rizotorfin”, “Nikfan”, “Phosphobacterin”, “Azotobacterin” and others.
Agrotechnical techniques
To prevent anthracnose in grapes, it is recommended to use agrotechnical practices. They are not methods of treatment, but they serve as a good means of preventing the development of infection. And if the bush has already been damaged, proper care will help speed up recovery. The main agricultural practices include:
- Proper planting of bushes, maintaining a minimum interval of 1.5-2 m or more (depending on the variety).
- Improving the ventilation of the crown - timely pruning, breaking off branches, pinching, thinning.
- Periodically inspect the bushes and remove affected shoots (it is better to burn them).
- Removing foliage in autumn. The litter should be taken and burned or thrown away.
- Treatment with insecticides and folk remedies for killing insects, many of which are carriers of anthracnose.
- Compliance with watering norms - many grape varieties are drought-resistant, so they are given water no more than twice a month.
- Timely application of fertilizing, loosening and weeding help increase the resistance of grapes to adverse weather conditions, anthracnose and other diseases and pests.
- The use of foliar feeding on the leaf is a low concentration solution of zinc or manganese sulfate (up to 0.2%).
One of the preventive measures is maintaining the distance between bushes and thinning the crown.
Preventative treatment
Preventing the development of anthracnose in grapes is much easier than dealing with the consequences. Along with the agrotechnical techniques described above, preventive treatment with chemical or biological preparations should also be carried out every spring:
- "Fitosporin";
- "Abacus Ultra, SE";
- "Strekar";
- "Ridomil";
- urea;
- Bordeaux mixture;
- copper, iron sulfate.
The first spraying is carried out in early spring, before the buds begin to swell, then two more with an interval of 10-15 days. During the procedure, it is also recommended to clean and water the tree trunk circle of the bush with a solution of the drug.
Grape varieties resistant to anthracnose
Many grape varieties are resistant to anthracnose infection. They can also suffer from the disease, but much less frequently compared to other varieties. Most often, gardeners give preference to the following varieties: Nimrang, Saperavi, Tsolikouri, Sauvignon, Riesling.
You should also take into account the varieties that are most vulnerable to anthracnose (at the same time they are resistant to downy and powdery mildew): Isabella, Husaine, Lydia, Karaburnu.
Conclusion
Anthracnose of grapes often affects the crop. Even if a variety is resistant to this disease, it still needs preventive treatment. In case of infection, they begin to fight the infection as early as possible, and for this it is advisable to use special drugs rather than folk remedies.
