Such a fungal disease as anthracnose often affects vineyards, due to which the fruits of the culture deteriorate, and the plant itself may die. Read below to find out what methods are suitable for dealing with this disease.
Description of the disease
Grape anthracnose is a disease that is caused by several types of fungus. If we translate the name of this fungal scourge from the Greek language, we get such a phrase as “coal disease”. This name is quite logical, since the affected parts of the grapes begin to look like they are charred.
This disease is common in places with high temperatures, and if high humidity is added to high temperatures, the fungus begins to actively spread and develop. Hence, ideal conditions for such a fungus are heat combined with frequent rains.
The incubation period of this fungal disease depends solely on the temperature of the air masses. So, if it is +12 degrees, then the incubation period lasts around 12 days, while at a temperature of +25 degrees, this time decreases to 1 week or less.
The fungus affects only young areas of grapes. These include foliage and petioles about 25 days old, shoots that have not had time to lignify, as well as green ridges, inflorescences and fruits. However, developing, the disease can affect already adult plants.
Signs of defeat
Anthracnose is clearly visible on berries, and on bunches, and on grape leaves. Initially, you need to pay attention to the leaves. Brown spots appear on them, around which you can see something like a dark border. In such areas, over time, you will see a hole that appears due to the fact that the tissues of the plant die off. When the disease is affected on the brushes of the plant, you can notice the presence of brown spots, which actively spread and increase in volume, due to which the living tissue subsequently dries and dies, and the buds begin to fall off.
On the shoots of the plantings, brownish spots will be found, which are oval-shaped and look like depressed. Often on such spots you can see a pinkish with shades of gray middle, which has a dark border. The tissues in these areas begin to crack, which is why ulcers appear in the future, and the shoots themselves begin to crack and dry. Similar signs can be observed on the ridges or cuttings of foliage. On mature berries, it is also quite possible to see similar symptoms.
Carefully inspect each part of the plant to make an accurate diagnosis and immediately begin to treat the disease.
Most often, the main cause of the disease is the penetration of its pathogen into the foliage or into the tissues of a vine damaged by something. Over time, infection of healthy parts of the grapes begins. How the further development of events takes place depends solely on weather conditions. Dryness and heat can help prevent the development of the fungus, while high temperature and high humidity, on the contrary, will only contribute to this.
Another common reason is improper watering. If you part with it and use too much water, then this will certainly lead to waterlogging of the soil and an excess of moisture in it, which will only give impetus to the development of the disease. Artificial sprinkling of grapes, the loss of a large amount of dew that occurs at night on foliage and shoots – all these are reasons that also provide favorable conditions for the spread of the fungus.
Also, the causes of the disease can be insufficient soil drainage, frequent rains or hail, as well as the long growth of the vine in dense plantings.
Excessively dense plantings prevent normal air circulation between them, due to which the soil dries slowly, and ideal conditions are created for a fungal infection.
Than to treat?
Anthracnose can be treated in different ways.
Most gardeners use fungicides as chemicals. These are effective drugs that can fight anthracnose. They can be used to treat both those plants that have recently become infected, and those whose disease is already at an advanced stage. Most often, modern summer residents prefer such means as Bordeaux mixture, Kuproksat, Skor, Fitosporin M, Acrobat C and Dnok. Each of these funds can be purchased in specialized stores.
In the initial stages of the development of a fungal disease, you can use a Bordeaux mixture with a concentration of 1%. If you are going to process the plant for the first time, then pay attention to the fact that young shoots should reach a size of 10 centimeters. After the first treatment, you must wait 2 weeks, after which you can spray the planting again, lowering the concentration of the drug.
If the disease began to progress in late autumn, then the fight against it should be postponed until spring. With its onset, the plants must be treated with a strong drug, for example, Fitosporin. It is possible to spray the vine with the agent only after cutting, which was carried out at the time the disease was detected – in late autumn. This must be done before the dissolution of grape buds.
It is best to treat the plant early in the morning or in the evening. Otherwise, it may get burned.
This is another way to fight against a fungal infection. Such preparations are also highly effective and, unlike chemicals, are completely harmless both to humans and to the plant itself and the environment. Among the biological agents, Mikosan and Guapsin are the most common.
Each of these drugs has a beneficial effect on grapes. Its taste qualities after application remain unchanged, but the shoots begin to grow somewhat more actively, which allows plantings to recover after an illness in a short period of time.
Treatment with such preparations must be done once every 2 weeks, and in this case it is necessary to act strictly according to the instructions. Note that it is necessary to process the plant for the first time only when its shoots grow to at least 5 centimeters or more.
Compliance with preventive measures is the best protection for your vineyard. Prevention will prevent the onset of the disease, it will also prevent it from spreading too much. Here several effective methods.
- Take good care of the plant. Check it regularly for disease. If it is found, the affected parts must be cut and burned in order to get rid of the fungus completely.
- Disinfect garden tools in special solutions after you treat the plants. This will also prevent the spread and occurrence of the disease.
- When planting plants, do not allow them to be too dense. Because of this, the earth dries out worse, which allows fungal diseases to develop freely. In addition, try to choose varieties for planting that are highly resistant to this kind of disease.
- Do not allow the growth of grapes. To do this, it is necessary to prune branches and shoots in time, as well as stepchild seedlings.
- Supply the plant with nutrients by using different top dressings. This will strengthen your grapes and their immunity, which will make the plant more resistant to various diseases.
- Try to avoid waterlogging the soil. Keep track of how much water you feed the crop.
The most resistant to anthracnose are such grape varieties as Riesling, Saperavi, Kodryanka, Yasya and Tangra. Please note that planting these plant varieties cannot give you a XNUMX% guarantee that your plantings will not become infected with this fungal disease. But the risk of catching it from them is still somewhat less than that of other varieties.
What is grape anthracnose, see the video below.