It is no secret that the gray coating that appeared on the leaves, and even more so on the berries of grapes, can upset any gardener. According to current statistics, various diseases lead to the death of about 30% of the crop annually.
And it is important to consider that ignoring the recommended preventive measures can increase this figure at least twice. If the grapes are covered with a gray coating, then this may be a manifestation of a whole list of diseases.
Causes
The described problem is one of the pronounced symptoms of bacterial plant diseases. As a rule, the activation stage occurs in the spring, and all parts of the grapes may be affected as a result. The list of fungal diseases that appear as a gray coating on the plant includes those listed below.
- Mildew – a disease that provokes a fungus that is as resistant to frost as possible. It actively develops with the advent of heat and in conditions of high humidity.
- Oidium – the most dangerous fungus for grapes, capable of causing maximum, irreparable damage. The leaves affected by the disease are covered with an abundant bloom, similar to ash or dust.
- Gray mold – affects ripening fruits, which as a result are transformed into a soft, actively rotting lump, covered with mold of the corresponding color.
- Antraknoz – Another dangerous fungal disease of grapes that affects shoots and berries.
- White rot – a disease, the signs of which most often become noticeable in hot weather and during a drought. At the same time, the fruits begin to turn brown, lose their elasticity and eventually fall off.
It is worth noting that in some situations, a gray coating on already ripe berries of white varieties can, to some extent, improve the taste of grapes.
In this case, we are talking about increasing sugar content, which will be most relevant in the context of making wine. But the appearance of bacterial mold on the fruits of red grapes leads to the destruction of the pigment.
Treatment
The main effective means of combating fungi and preventing their occurrence are fungicides. Based on the principle of operation, they are divided into three categories.
- Systemic, the list of which includes “Skor”, “Topaz”, “Kvadris” – drugs that can penetrate the stems and leaf plates of grapes, after which the juice is carried throughout the bush.
- Contact (“Shavit”, “Kuprozan”)acting directly in the hearth. These funds are washed off during precipitation, which is why processing is required more often.
- Complex (“Polychos”, “Paracelsus”), that is, combining the characteristics of the two previous varieties, therefore, being the most effective.
Practice has proven that the most effective is the famous Bordeaux mixture. By the way, this fungicide has been successfully used by gardeners over the past century. Its active components are lime (quicklime) and copper sulfate.
Depending on the disease, specific measures are required to treat plants.
- Mildew – spraying with a Bordeaux mixture, as well as treating the affected plants with Horus, Ridomil, Strobi, Kuproksat, Antrakol and Thanos.
- Oidium – pruning of damaged parts, treatment with fungicides “Thanos”, “Horus” and “Strobe”, as well as the introduction of phosphorus-potassium top dressing.
- Gray mold – pruning disease-damaged vines and treating the sections with a 3% solution of Bordeaux liquid or a 5% solution of vitriol. As part of the treatment, Switch, Sunilex, Euparen, Ronilan, as well as Ronilan and Topsin M are used.
- Antraknoz – processing of grapes with preparations “Ridomil”, “Antrakol” or “Hom”.
- White rot – removal of all affected clusters, followed by mandatory destruction and treatment of the bushes with preparations, which include penconazole or methyl theophanate. Horus performed well.
One of the most popular and effective folk remedies can be called a solution, which includes potassium permanganate, soda and iodine. To make it you need:
- in 1 liter of water (about 45 degrees) add 5 tbsp. l. soda;
- add iodine – 20 drops;
- dilute the resulting solution with 9 liters of water;
- add potassium permanganate to a light pink color;
- add 2 tbsp. l. grated laundry soap;
- stir the solution until the components are completely dissolved.
Whey is also successfully used for processing plants. It must be diluted with water in a ratio of 1:8. Grape bushes should be treated with this liquid at least once a week.
No less effective in the fight against fungi will be wood ash. It will be necessary to dilute 2 kg of ash in 10 liters of water and insist the solution for 2-3 days. Then a liter of the resulting mixture is diluted in 10 liters of water and the grapes are sprayed.
Preventive measures
It is important to consider that all currently existing drugs for the treatment of grapes are chemistry. To prevent both the disease itself and the negative impact of these funds on the plant and its fruits will allow the timely and competent implementation of preventive measures. And first of all, in order to counter the risks of plant infection with a fungus, it is necessary to ensure that there is air access to the vines from all sides. The lack of sufficient ventilation creates the most favorable conditions for the development of the fungus. However, an equally important point is the quality aeration of the soil.
It is important to remember that preventive measures are strongly recommended to start in the autumn. This refers to the competent preparation of grape bushes for wintering. They will need to be treated with copper or iron sulfate. These solutions have proven to be effective fungus killers. With the onset of spring, plants should be sprayed with a solution of the drug “Azophos”. It contains nitrogen, which greatly enhances the effect of copper.
The main thing is that the treatment should be carried out before the kidneys swell. In the future, fungicides are used before the flowering of grapes, as well as at the stage of formation of ovaries.
