A good vineyard is the dream of any gardener. A neat vine and large fragrant clusters create a special atmosphere. And how pleasant it is to pluck a finished dessert in the evening! However, grape cultivation has its difficulties, and primarily because the fruit vine is very loved by pathogenic bacteria and viruses. Today we want to analyze the reasons why white plaque appears on grapes.
Achievements of modern agricultural technicians
Only at first glance, luxurious clusters grow without any gardener effort. The most beautiful and delicious varieties are always struck in the first place. Despite all the efforts of breeders, this law cannot be overcome. Only varieties with a mediocre taste have a certain resistance to the most formidable diseases, including mildew. But if a similar grape, such as “Isabella” with sour blue berries, crosses with a good sweet variety, then resistance decreases markedly, and you can again notice a white coating on the grapes.
Shocking variety
If you are determined to grow delicious berries on your site, then you will need to pay a lot of attention to this. First of all, non-communicable diseases are dangerous for the vineyard, which are caused by heat or increased humidity, soil poverty or excess nutrients. They are easy to avoid if you ensure optimal conditions in your garden.
However, this list is not limited to, there are hundreds of different infections. If you observe a white coating on the grapes, you will have to smash your head, as a result of which it is. Infectious diseases spread through the vineyard very quickly. This leads to a significant loss of yield or death of the entire vine. Infection occurs through infected bushes, garden tools, as well as with wind and water. Imagine all the risks, and you will understand how important it is to constantly monitor the garden.
Downy mildew
Everywhere where there are vineyards, sooner or later will sprout mildew. Its causative agent is a fungus. It settles on living tissues and forms a white coating on the grapes. To get rid of this uninvited guest is not easy at all, as he hibernates on fallen leaves and in the ground, tolerates cold and heat. During the season, 20 generations of fungus can be replaced.
Outwardly, the disease manifests itself in the form of spots. In wet weather, a white coating appears on the leaves of grapes. When it's hot and dry, there are no such symptoms. To combat this ailment, preventive treatments must be performed. This will save your harvest and prevent a new outbreak.
Of the remedies, Antracol and Bordeaux mixture, Kuproksat, Thanos, and Horul are best recommended. The first treatment is performed when young shoots reach 15-20 cm in length. The second is necessary before flowering, and the third - when the berry is tied.
How to recognize mildew
At the initial stage of the development of the disease, this is not at all easy. Usually, people realize that the vine is infected when things become serious. You are very lucky if the summer is rainy. In wet weather, you can notice the fluff on the leaves and begin to act. But on hot days, even an experienced gardener will not notice the impending disaster. You can completely get rid of mildew only when all the bushes are removed from the ground. At the same time, spores of the fungus can wait for the appearance of a new vine for 20 years. Its growth can be restrained annually with special fungicides, do not miss preventive measures.
Powdery mildew
This is a dangerous disease that causes a white coating on the grapes. In scientific terms, it is called the oidium. The disease is caused by the fungus of the same name. At the very beginning of the growth of vine shoots, an attentive gardener can find among them those that are very behind in growth. Their leaves look curly, they are completely or partially covered with white dust. From June this plaque becomes noticeable on the lower and upper parts of the leaves. All inflorescences and clusters look as if sprinkled with flour.
White plaque on the berries of grapes in this case suggests that soon your vine will face big changes. Fruits burst and collapse. Oidium causes great damage to gardening. The incubation period is very short, and therefore you may not notice how the disease covers the entire vineyard. Most often, distribution occurs in wet and warm weather, as well as moderate humidity.
What awaits your vine
White plaque on grape leaves is just the beginning. Over time, the green mass will darken, then turn yellow and die. However, the affected leaves do not fall, but continue to hold on tightly in their places. New shoots of a plant or a planted fresh vine instantly becomes infected. With the onset of the cold period, the plant dies completely in 3-4 weeks.
If the growth of the vine has stopped, and you can already find black spots on it, you can be sure that the plant is slowly going to death. Why white plaque on the grapes is already clear. It destroys the fungus. However, even if the infection occurred at the end of summer, good is not enough. Half the crop will turn white and dry. Hoping for the second part is also not necessary. The remaining berries become soft, have a putrefactive taste. Winter will not bring you salvation either. The fungus will perfectly tolerate the cold and complete what was started next year.
Oidium Treatment
If the grapes are covered with a white coating, immediate action is required. This is a treatment with special antifungal drugs, such as Topaz and Strobi, Horus, Tiovit, Thanos. For treatment, you will need to repeat the spraying after ten days. However, this disease is much easier to prevent than to treat. Agricultural practices come down to airing the bushes by tying up shoots and pinching, as well as weed control. Follow the preventative treatment dates indicated for mildew treatment.
Alternariosis
This is another fungal disease that has been gaining popularity in recent years. Distributed almost everywhere. The hotter and rainy the weather, the more likely it will appear in your vineyard. It affects leaves, shoots and berries. Outwardly, it is very similar to an oidium. Already 10-14 days after infection, silvery spots appear on the leaves, and then mold. A film and velvety dusting is formed on the berries.
White plaque on bunches of grapes in this case says exactly one thing - the crop is ruined, but you need to try to save the vine itself. If the infection occurred at the end of the season, and because of too hot weather it did not develop, then the fungus will begin to grow after the harvest and spoil it all very quickly. To determine if the vine is infected, just take the part of the shoot that you thought was suspicious and place it in a humid environment. This will be enough to cover the material with a velvety coating.
Methods of struggle
Protecting the vineyard from alternariosis is not too complicated, but all activities should be carried out regularly. Of the biological products, good results are obtained by treatment with Trichodermin. So that the pathogen does not winter in the vineyard, in the autumn it is very important to clean your site and carefully burn all dry plants. Symptoms of this disease manifest themselves most often in the second half of the growing season, but they cannot be expected. Protective measures must begin in the spring.
“Bordeaux mixture” or special fungicides that contain mancozeb are very suitable for this. An example is the drug "Ridomil". Starting from the period of cluster formation, systemic fungicides should be used; examples include Skor, Quadrice and Rapid Gold. The interval between treatments is 10-14 days.
White plaque on the grapes: what to do
The signs of these diseases are quite similar, so distinguishing one from the other can be difficult. In order not to lose precious time, you need to start processing immediately. Therefore, if you notice a characteristic symptom, first prepare a solution of potassium permanganate. Add just a few crystals to the water so that it turns pink. It is very important that every leaf is wetted. Do this in the spring when your vine just wakes up. Even if the plant is not infected, it will be an excellent prevention.
When white plaque on grape leaves is already noticed, what to do in this case? Purchase several complex fungicides from a specialist store and use as directed. Alternating them with each other, you will not give the fungus a chance to adapt.
Emergency help
But what about in cases of severe damage to the vine? Let's see what to do if you missed the moment, and already on the grape white plaque. How to handle the vine in this case? Colloidal sulfur will help you . Not a bucket of water will require 10 g of active ingredient. Spraying can be performed every week until the flowering period of the grapes.
If the bush begins to blacken, then revise your plantings. The most affected plants need to be removed and burned, the rest must be carefully processed. We are not talking about berries, it is important to save the bushes themselves. Moreover, even if you had a successful treatment at the end of the season, it is recommended that the clusters be burnt so that they do not become a source of controversy. From spring, it will be possible to carry out preventive treatment and wait for a new crop.
Prevention
Having a certain experience and knowledge, the gardener must use modern methods on his plot to avoid unpleasant consequences. Beginners are a little more difficult, but they must also learn to protect their garden. This is especially true for those who grow varietal grapes. The disease can affect even the most well-groomed garden and spread through it with the speed of lightning.
In early spring, be sure to spray the vine with antifungal solutions. In late autumn, before folding the plant for hibernation, this procedure is repeated. But chemical processing is not all. Pay particular attention to the soil. Grapes draw a huge amount of nutrients from it. If it is not fertilized, then the vine will be susceptible to fungal diseases. It is advisable to feed using special mixtures that are sold in stores. Complexes that contain potassium, phosphorus, magnesium and other minerals are perfect.
It is very important to monitor the condition of the vines. The vineyard must be constantly moist, light and airy. Therefore, the bush must be trimmed and tied in a timely manner, remove stepsons. A well-groomed vine is easier to inspect, and compliance with all these parameters is a kind of guarantee that the disease will bypass it.
Growing a vineyard is a troublesome, but very thankful task. A well-groomed shrub will thank you for the time spent with sweet berries that can be eaten directly for food or harvested for the winter.