Rot On Grapes (14 Photos): What Does Gray, White And Black Look Like? What To Do? Fight Against It With Drugs And Folk Remedies

2024 Author: Beatrice Philips | [email protected]. Last modified: 2024-01-18 12:09

Grapes, like any other plant, are prone to diseases, among which rot can be distinguished. It is not considered a common disease, but if the gardener has encountered it at least once, then it takes a lot of effort to get it out. In this article, we will look at the types of rot and how to treat it.

Description and types

The disease is caused by the occurrence of the pycnidial fungi Phoma reniformis and Phoma uvicola . The disease can destroy almost the entire crop, not only bunches and fruit-bearing vines are affected, but also shoots completely. There are several types of rot. The most common among fruit crops is gray rot. It is dangerous for all plantings in the garden. Diseased grapes cannot be exported and stored. Without treatment, he can die completely.

Gray rot is visible immediately on the fruit in the form of purple spots that spread throughout the brush . Then it begins to die off when a dirty gray bloom appears on the berries, which looks like velvet.

If the fungus appears before the fruit ripens, even on the inflorescences, then they dry out before they have time to tie. Due to this disease, the taste of the berry is greatly reduced.

Black rot is very dangerous, vineyards that grow near water bodies are susceptible to the disease . Such rot appears due to mechanical damage to the trunk or fruits. Especially dangerous are damages that are received in the evening or with a drop in moisture and temperature. The lower parts of the bush are susceptible to the disease. External signs of the disease appear in May-June. White rot affects the crop by 50%, it can be identified by the light color of the peel, which becomes brown-blue over time. The entire brush is covered with a velvet coating. The infected fruit is unusable, loses its sweet taste and becomes bitter, after a while the brushes dry out and fall off. Grape varieties that have a thin skin are susceptible to acid rot infection. During the ripening period, the juiciest ripe bunches may be susceptible to the appearance of a fruit fly.

The insect not only feeds on the pulp of grapes, but also breeds an environment for the occurrence of fungal infections. Symptoms of the disease can be seen from the way the berry deteriorates, it becomes covered with red-brown spots, from which there is an acidic vinegar smell. Aspergillus rot destroys the crop almost completely . All bunches of grapes are susceptible to the fungus. The disease is also dangerous for other healthy plants. At first, the bunches of grapes brighten, and then acquire a dark color. The fruits shrink and then crack, turning into a bluish-brown mass. Root rot is also a fungal disease, a feature of this type of disease is that it has several pathogens. These are disease-causing fungi of a different order. The fungus penetrates under the bark or vine of the grape, then into the trunk and completely resolves the wood. In a diseased plant, the trunk becomes brown.

Contributing factors

The main reason for the appearance of rot is excessive moisture, which comes from prolonged rains or from excessive watering. The second important factor is the ambient temperature accompanying the fungus. Due to oversaturation with moisture, the berry swells and cracks. It is eaten by wasps and other garden pests, which contribute to the reproduction of the pathogenic environment.

Thanks to them, the pathogenic fungus enters the berry in the form of spores or mycelium. Due to moisture and weather conditions, it grows in the plant and spreads to others. The external manifestations of the disease indicate the rate of spread of the fungus in the tissues.

As a rule, these signs are visible already at the end of the disease, when sporulation has begun. It is at this stage that the plant becomes a source of infection.

The main signs

The symptoms of rot damage depend on the grape variety. The main manifestation is stains and rot on the berries, which are not typical for healthy grapes . Due to the development of pathogens, they soften, disintegrate and turn into a mushy mass of various colors. For example, due to gray rot, the berries are first covered with brown spots, and the leaves with a gray bloom, then they dry out altogether. If the disease began when the grapes have already ripened, then they become covered with dark spots, which then turn brown.

Signs of white rot are white bloom on the affected berries, which decrease in size, and the leaves also become infected and darken over time, then dry out . Sometimes such spots appear on the shoots. If you smell a pungent sour smell from grapes and see the presence of a large number of midges or wasps, then this is a characteristic sign of sour rot culture. For root rot, the first sign of the course of the disease is that in the lower part of the bush the leaves become small and yellow, there is no fruiting. The fungus dies if drought begins, but when moisture enters, it begins to grow again inside the roots of the grapes. In 2-3 years, you can lose a healthy plant.

How to treat?

Drugs

• For the treatment of any type of rot, chemical preparations are the most effective . "Topaz" is a systemic fungicide against all types of rot, as well as fungal diseases. It can be used for both prophylactic and therapeutic purposes. Thanks to the active substance penconazole, the reproduction of the fungus stops by blocking the reproduction of spores. The tool is sprayed on a grape bush, thanks to which its components quickly penetrate into the tissues of the plant. He is not afraid of temperature drops or long-term precipitation. During prophylaxis, the plant is protected for 8 weeks, and for medicinal purposes, its effect lasts up to 14 days. The drug is absolutely safe for humans and bees.
• Paracelsus fungicide can be used to combat vine rot to save the plant . This universal systemic contact drug is used not only for treatment, but also for the prevention of the disease. The main active ingredient of the drug is flutriafol, which systemically and contactfully fights the disease. When interacting with a phytopathogen, the drug disrupts the synthesis of the cell wall of the fungus and stops the growth of mycelium, and during evaporation, a kind of cloud is created around the treated culture, which protects the plant from the environment. The agent is absorbed into the tissues of the grapes within half an hour after spraying and is evenly distributed inside all its parts, including new shoots. "Paracelsus" is resistant to rain and watering. Keeps the plant from pathogenic fungi and microbes for 45 days. The product interacts well with other pesticides.
• Fungicite "Buzzer" has pronounced protective properties that help not only prevent the disease, but also get rid of its manifestation . It contains fluazinam, which acts on the pathogen in two ways. It inhibits the exchange of energy in the cells of the pathogen, stops the germination of spores and their vital activity. In order for the drug to begin to work, you just need to spray it on the plant. Within 7-14 days, it will be protected from rot and pathogenic fungi.

The drug significantly prevails over others, since it does not cause addiction and resistance in strains of the pathogen. The product has no phytotoxic effect.

Folk remedies

In the fight against rot, you can also use folk methods that are effective only in the initial stages and for the prevention of the disease. Spraying can be done with manganese and soda. Manganese is added to a bucket of water so that it takes on a faint pink color. 70 g of soda is added to the same solution. The finished product is used to treat a grape bush in dry and sunny weather.

Also, lactic acid bacteria are used to prevent the occurrence of rot. To do this, take milk whey and dilute it with water 1: 2. The plant is treated with the finished solution. Garlic infusion is also used to fight disease. To do this, garlic weighing 100 g is infused in 10 liters of water for a day, and then the bush is treated with a ready-made solution.

Prophylaxis

To avoid the appearance of the disease, it is necessary to carry out timely and regular preventive measures. The main condition for the healthy growth of grapes is timely pruning, which improves air exchange and light access. There should be no weeds around the roots of the bush. If a lesion occurs, then it is necessary to dispose of diseased leaves and affected berries.

As a preventive measure, treat the grape bush with copper sulfate or another copper-containing preparation, especially if it is a rainy summer or hail has passed . If you fertilize your grapes, then choose the preparations correctly, do not add organic fertilizers. Watering should be done in moderation and should be done together with loosening the soil. The use of nitrogen fertilizers improves plant immunity.

Resistant varieties

The resistance of grapes against rot is shown by red varieties, which contain some compounds that suppress the fungus. The thicker the skin of the berry, the less susceptible it is to infection. Sour varieties of berries are less sick with this disease. Therefore, the less sugar in the berry, the lower the risk of getting sick. The lower the density of a bunch of grapes, the better it is ventilated and available to light, therefore it is less susceptible to damage by the grape fungus.

The most resistant to rot are the following grape varieties: Riesling, Cardinal, Cabernet Sauvignon, Rkatsiteli and Merlot, Chardonnay.