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Pathogenic microbes often infect plants in the garden. Diseases have different origins. The cause of grape alternariosis is saprophytes - fungal microorganisms. In recent years, abnormal heat has led to the spread of the problem in many regions of the country. Therefore, it is important for gardeners to know the symptoms of the appearance and methods of dealing with parasites.
Description of the disease
The environment for the growth of fungal mold is high air temperature combined with high humidity. Such conditions often arise in regions traditionally suitable for growing grapes.
The causative agent of the disease is dangerous, first of all, to weakened plants. Fungal spores quickly spread over the ground part of the vine and cause necrosis of leaves and fruits.
Zarechny Maxim Valerievich
Agronomist with 12 years of experience. Our best summer cottage expert.
If you do not start treatment at the first signs of the disease, the garden culture may die within 5 days. Alternaria is dangerous for berries both during the ripening period and during storage of the crop.
How do the signs of alternariosis of grapes appear?
Symptoms of damage to grapes by pathogenic microbes appear already in the spring. Thunderstorms in May and air temperatures above 26 ° C create favorable conditions for spore infestation. Vines and leaves are covered with a silvery bloom and yellowish spots. As the disease progresses, the light blotches darken and then turn black. The shoots gradually dry out.
In summer, Alternaria also affects grapes. At the same time, the berries shrivel, acquire a gray tint and lose their taste.
Novice growers are often confused with signs of ailment with traces of oidium. To ensure the correct diagnosis, the shoots are placed in a humid environment. Fungal plaque quickly covers the entire branch of the plant.
Disease treatment methods
Alternaria treatment begins immediately in order to prevent loss of yield and death of the grape bush.
To combat fungal diseases, drugs containing copper are chosen. Stages of preparing a plant treatment agent:
- Slaked lime is diluted in a separate container and filtered.
- The solution of copper sulfate is filtered.
- Combine the resulting mixtures.
Grape growers use other spray chemicals as well. It is recommended to treat a diseased culture according to the following scheme:
|Processing time||Applied means|
|During the period of swelling of the buds after the garter of the shoots (from March 20 to April 10)||Prevention with copper fungicides|
|After the leaves appear (from April 25th to May 10th)||"Trichodermin"|
|Before fruit ripening (every 2 weeks, starting from the last days of May)||Use one of the drugs: "Rapid", "Quadris" or "Cabrio-top", as well as "Skor"|
Spraying times vary depending on weather conditions. And the procedure must be repeated if it rained immediately after processing the grapes.
Folk remedies and recipes
At an early stage of the disease, alternative methods are also effective for the treatment of Alternaria.
To prepare the mixture, you need to pour about 3 kilograms of manure with a bucket of water. The resulting composition is left to infuse. After 3 days, the solution is filtered and then the vine is processed.
Spraying manure is not used fresh, but after a short pause to avoid burning the leaves. A folk remedy for Alternaria is popular in small private vineyards, and even in large farms engaged in mass cultivation of crops.
Potassium permanganate solution
The tool is obtained by diluting 5 grams of potassium permanganate in 11 liters of water. Agronomists advise observing the dosage so as not to burn the surface of the leaves. During preparation, they are guided by the color of the solution. The required concentration gives the liquid a slightly pronounced pink tint.
Potassium permanganate is sprayed on the grape bush completely, and not only on the affected shoots. Early shoots are watered at the root.
Sometimes a mixture of milk and water is used to combat Alternaria. The proportions for the preparation of the solution are 1 to 10. The composition is poured into the sprayer 30 minutes after stirring. The ground part of the vine is processed. The heat activates the development of bacteria, which expels fungal spores.
The effectiveness of the method is not very high. This method of treatment is used for early detection of the disease.
Laundry soap with soda ash
Ordinary laundry soap also copes with the alternaria of grapes. To treat the fungus, stir 30 grams of the product in a bucket of water and add the same amount of soda ash. The mixture forms a film on the leaves that inhibits the spread of spores. And the alkaline environment destroys pathogenic bacteria. Spraying is useful to repeat after 10 days.
Prevention of infection
The prevention of grape Alternaria involves a comprehensive implementation of measures:
- Mechanical ways to prevent the disease are to regularly prune the infected shoots and then burn them.
- Agronomic methods mean the use of fertilizers and concentrates with microorganisms. Useful substances will strengthen the plant's immunity and prevent harmful bacteria from developing.
- Prevention of a chemical orientation involves treating the vine with preparations with copper. Experienced growers alternate copper sulfate with a 2% Bordeaux mixture.
As additional measures, they use the introduction of mineral complexes, timely watering and loosening of the soil. Removing weeds from the site will have a beneficial effect on the development and ripening of grapes.
Some grape varieties are highly immune to disease. Alternaria rarely affects such plants. Gardeners advise growing Rkatsiteli or Traminer. Resistant to pathogenic microbes Cabernet Sauvignon and Riesling. Amur varieties have proven themselves well - Triumph, Breakthrough. Marinovsky or Amethyst grapes do not cause problems.
Preventive measures allow you to avoid problems with growing crops. At the first suspicion of alternariosis, treatment of the plant should be started immediately. A neglected disease will make it impossible to harvest a good harvest of healthy and tasty berries.