How and how to treat grape diseases?
Like any crops, grapes are susceptible to many diseases. Sometimes this is due to improper care, and sometimes bad weather makes adjustments. In any case, you need to know the enemy by sight and be able to fight him..
Diseases of grapes: description, signs
It is customary to divide grape diseases into several categories: fungal and viral. The first is the most famous and widespread. To cure infected bushes, fungicides are required. The second category is the most serious. In most cases, processing does not help, you have to completely remove the bushes, as well as comply with quarantine measures.
Fungal diseases of grapes
- Mildew (downy mildew). The most common fungal disease of grapes. It manifests itself in the form of yellow spots and gray (moldy) plaque. Affected areas dry out quickly without proper treatment. The disease develops with lightning speed in wet weather. It is impossible to completely cure such a plant – the fungus is inside. It is possible only with the help of special drugs to prevent the course of the disease..
- Oidium (powdery mildew) is the second most common fungal disease. Affected leaves are covered with a gray bloom. The disease can occur at any time of the summer. A favorable environment for the development of pathogenic bacteria is the air temperature within +25 degrees. Oddly enough, torrential rains can stop the spread of the disease. With a severe damage to the plant, the skin of the berries begins to crack, and the fruits become unusable. If you do not take any measures in time, you can be left without a crop, and after 2-3 years completely forget about the existence of the vineyard..
- Alternaria is a fungal disease. The main sign is the presence of brown or silvery spots on the plant. Leaves, fruits, petioles, and also shoots are susceptible to the disease. If the blow fell on the berries, then they are covered with a white film, shrink and quickly deteriorate. A protracted spring is a favorable condition for the rapid development of Alternaria.
- Bacterial cancer is a fungal disease that predominantly affects the vine. A clear sign is growths that appear on the shoots. There are no remedies that would help heal the plant. Therefore, it is better to pull out the affected bush and burn it right away. It is noteworthy that grapes cannot be planted in its place for three years..
- Apoplexy is a disease in which there is a sharp death of the plant. Experts explain this phenomenon by the fact that pathogens appear in the plant that produce toxins. They then destroy the plant. Weakened bushes are most susceptible to this disease..
- Gray rot is a fungal disease. It appears as a gray bloom. It can form on absolutely everything: shoots, tendrils, inflorescences, fruits, etc. The crop is not fit for food. It is especially dangerous when the fungus forms on the bunches of grapes. All fruits can suffer from one infected berry..
- White rot is a clear sign of the disease, it is a white bloom on the stem and berries of the plant. Most often, the fungus occurs after hail – when the plant is damaged. Infected berries change color and subsequently fall off..
- Black rot is a disease in which purple spots form on the leaves and berries. Over time, they grow, and the affected areas shrink and fall off..
- Verticillosis – characterized by the rapid wilting of the shoots. In the acute form, yellowing and leaf fall are observed. The plant can become infected through damaged branches or through the ground. In the soil, the fungus persists for about 4-5 years, therefore, it is not recommended to plant grapes in an infected place during this time..
- Armillariasis is a clear sign of the disease – wilting of leaves and root damage (they become rotten and acquire a brown tint). Usually these signs appear in the spring, and in the fall, yellow mushrooms grow on the dead bushes..
Viral diseases of grapes
Viral diseases are poorly understood today. The disease can be caused by a certain group of viruses. In particular, we are talking about infectious chlorosis, yellow mosaic, rezuha mosaic, etc. The main signs that may indicate a plant infection with a virus include:
- Slow bush development;
- Dying off of inflorescences;
- Twisting or any deformation of the sheets;
- Unusual color of leaves, for example, variegated;
- Wood cracking.
Unfortunately, no measures will help in this case. The affected bush is simply uprooted and burned. The infected site is not used for new plantings for at least 5 years.
Getting rid of diseases: a list of the most effective drugs
The list of drugs that help fight grape diseases is quite a lot. Now we will talk about the most famous and effective ones..
Strobi fungicide: instructions for use for grapes
Strobi fungicide is a drug designed to fight fungal diseases. These include:
- Late blight;
- Powdery mildew.
It should be noted that this tool has many advantages. In particular, the preparation is safe for insects (this circumstance is important for beekeepers), and it can also be used during flowering..
Principle of action: the active ingredient is kresoxim-methyl. It evenly lays down on the leaf surface and creates a gaseous shell that protects the plant surface..
Application: a 10-liter bucket of water requires 5 g of “Strobi”. It is necessary to treat the plant evenly with the prepared working solution. This should be done early in the morning in sunny weather..
It is recommended to use the prepared product no later than 2 hours after its preparation. Otherwise, the long-awaited effect may not be achieved..
During the season, processing is carried out 2 times (this is quite enough). The interval between them should be 10-14 days. The final treatment should be carried out at least one month before harvest..
Ridomil Gold: instructions for use for grapes
This drug has also become widespread. It is effective against mildew.
Principle of action: in the composition of “Ridomil Gold” there are such components as mancozeb, mefenoxam. The first protects the surface of the leaves, while the second penetrates the grape bush and thereby provides it with internal protection. After treatment, the plant will be fully protected for 2 weeks..
Application: To prepare a working solution, you will need 10 g of a product for 4 liters. water. Treatment takes place by spraying the working fluid on the plant. It is advisable to carry out this action during the growing season. The interval between spraying is 10-14 days. The last treatment must be done at least 2 weeks before harvest.
Ridomil Gold is a prophylactic agent. It helps prevent illness. If the plant is already infected, then first you should use a curative fungicide, and after it (after about 7-10 days) resort to the use of “Ridomil”.
Topaz: instructions for use for grapes
This drug is effective against powdery mildew, powdery mildew. It is produced in the form of an emulsion in ampoules..
Principle of action: after treatment, the active ingredient – penconazole, is quickly absorbed by the plant. Having penetrated inside the agent, it does not allow the formation of new mushrooms. If the use of “Topaz” occurred at an early stage of the disease, then the effect will be most noticeable..
Application: one ampoule is enough for a 10 liter bucket. The prepared solution should be sprayed with plants affected by the fungus. It is best to do this early in the morning or in the evening in dry and calm weather. Re-processing of grape bushes can be done in 10-14 days..
During the preparation of the working solution, some safety measures must be observed. In particular, the use of special protective goggles and gloves is recommended..
Tiovit jet: instructions for use for grapes
“Tiovit Jet” for grapes is in no way inferior in efficiency to the above means. He does a good job with powdery mildew.
The active ingredient of the drug is sulfur. On sale, it is sold in the form of granules. The weight of one package, as a rule, is about 800 g.
Principle of action: when it hits the plant, sulfur is released, it then gets on the pathogenic cells and completely destroys them after a few hours.
Treatment with the drug should be carried out in warm weather. If the temperature is low, the sulfur will not evaporate, which means that the desired effect will not follow.
Application: Jet is very economical to use: 30-80 gr is enough for a 10-liter bucket of water. substances. Processing is carried out by spraying, mainly in the morning. The drug can be used up to 5 times per season. When using the drug, do not forget to ensure that the working solution is evenly distributed over the surface of the sheet. Jet will start working in about 2 hours after spraying.
Quadris: instructions for use for grapes
Quadris – the use of this drug for grapes is very common. This is because it can help get rid of many diseases. Among them:
- powdery mildew;
- mildew, oidium;
- late blight;
Application: The drug can be used both for prophylaxis and for direct control of the ailment that has arisen. Treatment (spraying) of plants is best done in the morning, when the sun’s rays are not yet so merciless. The main feature of this remedy is that it must be alternated with other drugs. For example, you can first treat the plants with Quadris, then Horus, and then again with Quadris.
Principle of action: “Quadris” has a unique effect on the treated plant. Getting to the affected areas, it can nullify the disease that has arisen within 3 days..
The advantage of “Quadris” is that it combines well with many drugs. For a 100% result, the product can be mixed with Ridomil, Topaz or Revus. The second undoubted plus is that this drug shows good results in wet weather, therefore, it copes well with fungal diseases.
Do not process when the foliage surface is wet or precipitation is expected in the near future..
And one more important point – repeated use of the drug is allowed no earlier than 2-3 weeks..
Summing up, let’s make an important note: the disease is easier to prevent. At the moment when the plant is already infected and clear signs of the disease began to appear on it, there is less hope for a good outcome. Of course, one must be prepared for the fact that even if the grape bush is lucky enough to recover, the yield will still decrease. In any case, the use of fungicides is justified and sometimes is the only way out of this situation..