Grapes are a tasty and healthy berry. A real storehouse of vitamins. To reap a high harvest, it is necessary to protect the grapes from gray and other rot on them; you need to know what and when to treat the vine. When infected with a fungus, entire bunches suffer. Even young shoots and leaves. The task of the winegrower is to prevent diseases or effectively combat ailments that appear on the plant.
What types of rot are there?
There are several types of rot.The most common are gray, white, and black rot.
Gray rot on grapes is more common than other types. It can affect different parts of the plant. The fungus has a detrimental effect on the crop. Infected berries are not suitable for food or processing. If the disease is not stopped in time, it can affect the entire vineyard.
No less dangerous is the appearance of white rot on grapes. If the fungus is not detected in time, it will destroy most of the crop. Another danger lies in the possibility of damaging other cultivated and wild plants.
Black rot that appears on grapes differs from others in that it overwinters on the vine. After the shoots begin to grow, the plant becomes infected. This occurs in late spring or early summer when it is warm and humid. Near bodies of water this process occurs faster.
Reasons for appearance
The causes of rot infection are different. Why do grapes rot? This is largely influenced by weather conditions. Long rains favor the appearance of gray and black rot. White occurs after long dry days.
Gray rot affects the entire plant. But it is especially dangerous for ripe berries. If there is excess moisture, the skin bursts, and the fungus quickly multiplies in favorable conditions. The same result occurs after hail falls, which injures the delicate skin of the berries. Damage is caused by wasps and garden pests.
When berries are infected with black rot, part of the crop dies. Shoots and leaves are not in such danger.
In the spring, the white rot fungus awakens, having overwintered in the bark and fallen leaves, and attacks the shoots. Sunburn is another reason for the rapid spread of the disease. If affected berries are not harvested in time, healthy fruits become infected.
Signs of diseases
Signs of diseases of different types of rot differ from each other.
When affected by gray rot, the leaves first become covered with brownish spots with a gray coating. Then they dry up. When the disease occurs during the flowering period, the inflorescences dry out before they have time to grow. If the bunches have already formed, then during infection by this fungus on the berries dark spots appear in grapes, turning into brown over time.
A sign of white rot is a white mold coating the affected berries. Their size decreases. Leaves become infected, darken and dry out. Less commonly, spots appear on shoots.
With black rot, the berries darken, lose their elasticity, wither, wrinkle and rot or dry out. This fungus first appears on the leaves as small brownish spots with dark edges.
Detrimental effect on grapes
The environment has a detrimental or beneficial effect on the yield and quality of fruits. Only under optimal climatic conditions is high quality grapes possible. It depends on the growing conditions of the plant from planting to harvest.
The volume of the harvest is affected by the moisture content in the soil and the number of sunny days. Threats to the growth of seedlings can include drought, intense precipitation, hail and early frosts.
During prolonged rains it becomes cooler and the grapes ripen poorly. The berries have insufficient sugar content and excess acid. As a result, their quality suffers. If there is too much water, the grapes will burst, providing a breeding ground for fungal diseases.
During prolonged drought, the growth and ripening of berries is delayed, metabolic processes are disrupted, moisture evaporates faster, and the pulp loses its juiciness. This leads to the death of more than one brush.
At high air temperatures, sunburn can occur, affecting not only the leaves, but also the berries. Damaged leaves become covered with plaque and brown spots. Then they dry out and fall off. This opens up other parts of the vineyard that also deteriorate. The burn most often appears after watering, when drops of water remain on the surface, which act as a natural lens.
To protect plants from sunburn, when watering during hot periods, it is necessary to avoid getting water on the leaves and berries. In the hottest sunshine, cover the bushes with a soft cloth.
Frosts also have a bad effect on the harvest. Even after a slight frost, the vineyard does not look its best. The supply of sugar to the berries is limited; they do not ripen. When frosts intensify, berries fall off. The leaves are disappearing.
For high productivity, the vineyard needs good lighting. With a lack of light, the leaves become smaller and the shoots become thinner. The development of inflorescences slows down. The clusters are less well formed and the fruit buds are poorly formed. The flowers fall off and the yield decreases sharply. Vineyards growing on slopes and hills are better illuminated.
With proper care of the vineyard, the volume of the harvest and its quality increase. Proper planting, tillage, bush formation, pruning, and pinching play an important role.
If the vines are not staked, they will come into contact with the ground, contaminating the grapes. At the same time, the berry rots and cracks, becomes infected with mold, and disappears.
The most vulnerable varieties
Not all grape varieties are susceptible to rot, but there are shrubs that are especially sensitive to this disease.
Gray rot most often affects those grape varieties that have a dense bunch and a high degree of sugar content.For example, such early ripening grape varieties as: Golubok, Zhemchug Saba, Rusbol, Muscat Tairovsky.
The following varieties suffer from white rot more often: Rhine Riesling, Seibel 1, Plavai, Alimshak.
The following varieties are susceptible to black rot: Italy, Muscat Hungarian, White Chasselas, Pearl Saba.
Methods and tips for treating rot
The main thing is to detect signs of infection in the early stages. This will help get rid of the disease and save most of the harvest.
To treat white rot on grapes, the following control measures must be taken.
Before treating with antifungal drugs, the bush must be freed from infected parts. If there are two or three berries damaged by rot on the bunch, you need to remove the entire bunch of grapes. There is a high probability of infection spreading to other fruits.
Bordeaux mixture is suitable for processing the vineyard. Spraying should be done in the early morning or evening. Preparations containing theophanate methyl or penconazole are considered an effective remedy for ridding shrubs of rot.
You can spray grapes against gray rot with the following preparations: Smilix, Switch, Ronilan. Treatment is carried out four times per season. Treatment can also be carried out using copper sulfate. 15 grams of the drug are diluted in ten liters of water.
What to do if the vineyard is affected by black rot? First of all, you need to remove the damaged parts of the bush. Then process grapes special preparations, such as: Antrakol, Topaz, Bayleton. The first spraying is carried out after the leaves bloom, then before flowering begins, and the third time during the growth of the berries.
Final spraying is carried out in the fall, after harvesting. If it rains after treating the grapes with the preparations, it is necessary to repeat the spraying again.
Methods to combat and protect grapes from rot include preventative spraying of the bush once a month. Favorable conditions for the development of grapes will also play an important role. As you know, it is easier to prevent a disease than to cure it.
Folk methods of struggle
Many summer residents are wary of treating grapes with chemicals. They ask themselves: how to fight fungus with folk remedies? There are several effective solutions that will help in the fight against rot:
- Dissolve 50 grams of mustard powder in 5 liters of hot water. Leave in a dark place for two days. Before spraying, dilute the prepared mustard solution with water 1:1.
- Add ten drops of iodine to a bucket of water and stir. Treat the vineyard with the solution once a week.
- You need to dilute 70 grams of soda in ten liters of water. Spray the fruits and leaves of grapes with the resulting solution in case of minor infection.
- Dilute a one hundred gram piece of laundry soap in ten liters of water. Spray the grapes with a soapy solution in cloudy but not rainy weather.
- Dissolve 50 grams of soda ash in a bucket of water, pour in 40 grams of oil. Treat bushes with this solution once every ten days.
- Dilute a liter of kefir or sour milk in five liters of water, add twenty drops of iodine. Spray once every ten days.
- Pour 100 grams of dried horsetail into a bucket of water and leave in a dark place for 24 hours. Then simmer for two hours over low heat. Strain the finished broth. After cooling, dilute with water 1:5. The decoction is stored for seven days in a cool place.
But do not forget that folk remedies can be used for mild forms of infection, or as a disease prevention.In case of severe infection, it is worth using fungicides.
Prevention measures
Before growing grapes, it is necessary to select a suitable variety in accordance with the climatic conditions of its further growth. To protect and prevent diseases, it is necessary to create normal conditions for the growth and development of the grape bush:
- First of all, there is sufficient lighting.
- Timely pruning of the vine.
- Properly selected fertilizer.
- It is not recommended to add organic fertilizer to the shrub.
- Produce all bait according to schedule.
- Keep the soil under the bush clean, avoiding rotting of leaves and fallen berries.
- Moderate watering, loosening the soil, good ventilation of the bunches, constant inspection and spraying of the plant.
The preventative agent can be used when the shoots reach fifteen centimeters, and in the fall, after harvesting. The bush must be treated with copper-containing preparations or potassium iodide.
