What is the disease of grapes? Mildew: treatment of the disease, the causes of the onset and prevention

Most grape diseases can destroy crops or significantly reduce the quality of berries. For this reason, the fight against them is extremely important. Among the diseases the most widespread was mildew grapes. Treatment of this disease is conducted in accordance with the methods of combating fungal infections of plants.

The disease of the plant is the result of the infection. The cause of the development of pathogenic microbes can be transmission (infection) to a healthy plant of microorganisms from the patient. Also on the development of diseases affect the climate, the characteristics of the soil and other conditions for the growth of plant culture. Pest microorganisms can develop in the soil, in damaged areas of the plant or under the influence of unfavorable weather conditions. The most dangerous for the family of grape are parasitic fungal microorganisms. Fungal diseases of plants are caused by phytopathogenic parasites.

Preserving grapes: diseases and mildew treatment

A particular danger of fungal diseases is the rapid spread of infection. They can cause significant damage to the plant in a few weeks and dry the bushes of grapes for 1-2 seasons. The speed of the spread of the disease depends on the type of infection and weather conditions. For example, mildew (fungus of downy mildew) actively spreads in rainy weather, while the oidium (mung bean uncine grape) during the rain completely stops development.

Response measures should take into account the prevalence of infection in the area of growth. In the middle and southern regions of Russia, the mildew grapes are most often affected. Treatment of a fungal infection is as follows:

• Preventive measures - spraying with antifungal agents, pruning unnecessary shoots, grappling the vine, removing diseased leaves and twigs, removing weeds, etc .;
• Maintenance and strengthening of the agrofon;
• Preventing the spread of sick plants and fruits - quarantine.

Mildew - the most dangerous fungal disease

Mildew - powdery mildew, the causative agent of which is the fungus of the plasmaparatic vitil. This type of disease is the greatest danger for European varieties of grapes. The parasitizing microorganism affects all the greenery of the vine: the foliage, vegetative organs, inflorescences and fruits.

Affecting inflorescences and berries, the fungus completely destroys the harvest. The deciduous cover of the grapes under the influence of the fungus withers, after which it falls. A sharp reduction in the area of deciduous surface disrupts the process of correct ripening of the fruit. Berries of sick bushes lose their nutritional value and sweetness, cooked from them sour wine tastes. The sick vine is badly ripening, this negatively affects the resistance of the bush to winter cold.

Fungus, affecting the plant, especially actively develops on young inflorescences from individual pedicels or ridges. Affected areas of disease are turning brown, all the ovaries with inflorescences, which are below, perish. Under the influence of rain, the fungus actively spreads and destroys the plant.

Terms of distribution of mildew

Fungal infection hibernates in the form of spores on fallen grape leaves and soil. In spring, when the soil becomes very wet, and the air temperature lasts 7-8 days at a level of 10 degrees, the fungus sprouts and sprouts.

When they are in a moist environment or rain puddles, they begin to grow actively. In the process, they form a living environment for the formation of zoospores (zoosporangia). After the zoospores are formed, they are carried by the wind to the bushes, and the fungus begins to parasitize, infecting the mildew grapes. Treatment, description of the disease and its prevention will be considered further.

Description of mildew

Visually the development of the disease begins with small spots of yellow color, over time covering the entire area of the leaf. A sign of the spread of the disease is the appearance of a white cannon in the lower part of the leaf formed after the rain. The infected leaves completely turn yellow and die. Recognize mildew on the vine can be on the spots, like small points brownish hue.

The greatest danger is the microorganism for young inflorescences, as the sporification of the fungus is formed on their surface. Young inflorescences under the influence of mildew die - the berries blacken, frown and crumble. The spread of the disease stops in dry, hot weather, air temperature above 30 degrees.

General rules for disease control

If infected with mildew grapes, treatment is done by spraying with a pesticide that destroys the primary foci of infection. Before the grapes begin to bloom, the bushes are sprayed with antifungal mixtures. The next stage of spraying begins immediately after the beginning of flowering and the appearance of small berries (the size of the head of the match). Consider the methods of fighting the disease in more detail.

Method of counteraction of mildew

The main stage of the organization of the struggle is to provide conditions that hinder the development of the disease. The infection that promotes the development of mildew lives in places of high humidity, in lowlands, which for a long time detain rain puddles, dew and fog. The complex of agrotechnical works promotes better ventilation of plants and excludes accumulation of excessive moisture near grape bushes.

As has been said, spores of mildew hibernate in the fallen grape leaves. In autumn, after harvesting, the fallen leaves must be burned.

Spraying the bushes of grapes with poisons that destroy fungi is the most effective way to preserve the crop. As a rule, they are produced by 1% solution of Bordeaux liquid. For the first spraying, a solution of 0.5% is used, the subsequent treatment is performed with an increase in the concentration from 0.75% to 2%. Low content of the active substance does not allow the antifungal solution to burn the leaves and shoots infected with mildew of grapes. Treatment (photo below shows the process) involves spraying the vine bushes with a tank mixture in order to prevent infection.

Antifungal mixtures for grape spraying

There are various folk methods and preparations for combating mildew grapes. Treatment with folk remedies is effective as prevention. An effective method of treatment is spraying with solutions containing active chemical components. Antifungal solutions contain zinc and copper sulfate. The most accessible and effective drug is a solution of Bordeaux spraying liquid.

Mixtures containing various components for spraying plants are called tank tanks. Mix mixtures for the treatment of grapes from mildew contain the active substance - copper sulfate. The mixture of Bordeaux liquid consists of slaked lime slurry in the calcareous water and copper sulfate.

Characteristics of the active component of the Bordeaux mixture

It should be remembered that a solution at a concentration of more than 3% copper sulfate is capable of burning the surface of grape leaves. The main active component of the Bordeaux liquid is characterized by rapid dissolution in water, so the rains in a short time remove the medicinal mixture from the surfaces of the grape bush.

To keep the solution of copper sulfate as long as possible on the surface of the plant, it must be mixed not with water, but with lime milk. Lime neutralizes the acid reaction of copper sulfate, the liquid becomes viscous and sticky. Sticking to the leaves of grapes, the substance is retained longer on the surface under the influence of rain.

In order to effectively combat the mildew of grapes, treatment should be carried out with a preparation that is prepared according to technological norms. The qualitative characteristics of all components are important.

Paying attention to the main active component - copper vitriol, you should make sure that the powder does not contain any foreign impurities, and its color is bright blue. Lime for mortar is suitable as a slaked or quicklime. However, it is better to perform quenching during the preparation of the solution. It is freshly lime that provides the best adhesion of the drug to the surface of the grape leaves.

The proportions of the solution of the Bordeaux mixture

All preparations for the treatment of mildew in grape have a predetermined safe concentration of the active ingredient. The concentration of copper sulfate in a solution of the Bordeaux mixture can be from 0.5% to 3%, a higher content of the active substance will burn the leaves. To prepare 10 liters of the drug with a concentration of 1% of the active substance, you should take 100 grams of quicklime and the same amount of copper sulfate. Mixing is carried out in containers, the material of which is resistant to chemical reactions and does not interact with the components of the solution. Optimum option - a glass or ceramic container, the use of galvanized or metal containers is unacceptable.

To prepare the mixture, dilute copper sulfate with one liter of hot water. Once the powder has dissolved, 5 liters of cold water are poured into the container. Separately, quench 100 g of prepared lime, then add the rest of the water and adjust the volume of the lime solution to 5 liters. The preparation of lime is filtered. A solution of copper sulfate is gradually added to the resulting lime milk. The process of combining the components is accompanied by constant stirring.

It should be noted that a solution of lime is added to the solution of copper sulfate, and not vice versa. With an unreasonable sequence of actions, the resulting suspension will not be effective in controlling mildew, the active components will precipitate.

Characteristics of a properly prepared product

The solution of the Bordeaux liquid, which is prepared according to the technology, has a blue color and a mucous structure, adheres to the fingers. Color can signal the concentration of the active substance. For example, green means that the copper sulphate is added to the surplus, and when sprinkled, the liquid will burn the grape leaves.

Is the mildew grapes sick? Treatment: how to treat the Bordeaux mixture?

It should be remembered that only a freshly prepared solution is suitable for processing grapes. Bordeaux liquid during storage loses its useful properties and becomes neutral for fungal parasites.

If the visual inspection shows that the mildew grapes are sick, treatment with a solution of the Bordeaux mixture is the optimal solution. To ensure the safety of the prepared product, a metal nail is immersed in it for a short time. If the nail is not covered when removing the nail, the solution is safe for plants. The appearance of small grains on the surface of the nail will tell about the low quality of the Bordeaux liquid and the large content of the active component. In this case, it should be further diluted with a lime solution.

However, the Bordeaux mixture prepared according to the technology is also able to harm the grapes, if the spraying is performed on a hot day after the heavy rain. In order to minimize the risk of burns in plants, treatment is performed at dawn or during sunset.

Prevention of viral and fungal diseases of grapes

The maximum effect is given by measures to prevent fungal and viral diseases. Prevention is conducted in the period of three seasons: spring, summer and autumn. During this time, plant growers watered bushes, cut the vine and strengthened the agrophone, fertilizing the soil.

Before spraying the grapes, it is necessary to remove damaged leaves, trim unnecessary shoots and tie a vine. Garbage in the form of diseased leaves and shoots must be burned, preventing the development of infection.

Grapes care before harvesting

It is extremely important to perform mildew treatment on grapes in July. In summer, before harvesting, plant growers carry out the main spraying of bushes. The schedule of treatment with a solution of the Bordeaux mixture - every 3 weeks, starting from the first of July. Spraying of grapes with antifungal agents is completed in the first decade of August and is not conducted until pruning of the vine.