The content of the article:
If before fungal diseases of grapes were not too often reminded of themselves, now this problem is becoming more urgent. One of the most common was the disease of grapes oidium, which affects an increasing number of plants in all regions of the country, bringing a lot of trouble to wine growers.
What is oidium?
Oidium is the most common fungal disease, which has other names - ashtray or powdery mildew. His pathogen lives exclusively on living and green tissues. Powdery mildew makes grape berries unsuitable for consumption and for the production of wine from them.
The largest epidemics of oidium occur after winter frosts (the temperature should not fall below -30 ° C). The spores of the disease persist under the scales of the eyes, and when the temperature rises to +18 ° C... + 25 ° C they begin to germinate. Promotes the development of the fungus and high humidity. But rains can significantly slow down, and in some cases also stop its spread.
To reduce the chances of infection, grape must be selected varieties that have high resistance to disease, remove excess shoots, cut off diseased parts of plants and burn them. Do not use fertilizers with an excess of nitrogen.
Symptoms of the disease
Symptoms of oidium, manifested at different times of the year, differ.
The following signs appear in the spring:
- Yellowing of young shoots and leaves covered with a dirty white coating, similar to flour.
- The edges on the leaves wither and curl.
- Under a white coating on green shoots, brown spots begin to appear. If you try to erase the plaque, then there is the smell of foul fish.
- With a strong lesion, shoot growth is disrupted, and their tissues begin to die.
In summer, these symptoms are somewhat different:
- Flowers and young clusters wither, and the crests of leaves become fragile.
- As they grow, the young berries are covered with dark spots, and later the mesh pattern appears on them and its testing takes place.
- The berries begin to crack and rot. The development of the disease on them can continue until harvest.
Prevention and control of the disease
If powdery mildew was found on grapes - how to deal with it becomes a very pressing issue. There are several ways to get rid of this fungal disease.
The use of sulfur and sulfur preparations
Being in a dispersed form, sulfur is very effectively absorbed by the fungus, where it turns into hydrogen sulphide, which kills it. It is best to treat sulfur in the morning or in the evening, because with severe heat, burns can occur on the leaves and fruits. The treatment is repeated every 10-20 days. For prophylaxis it is necessary to dissolve 25-40 grams of sulfur in 10 liters of water, and to treat 80-100 grams.
Before spraying grapes, it should be taken into account that sulfur treatment is effective only at an air temperature of more than +20 ° C, at lower temperatures it is ineffective. If the temperature falls lower, then it should be treated with colloidal sulfur or one of sulfuric drugs.
Contact and systemic drugs
During the ripening of berries, you can not use chemicals. Therefore, use a solution of potassium permanganate to delay the development of the disease. For treatment, complex preparations that are acceptable for use during ripening are best suited.
Biological methods against oidium
The most accessible of all methods is the preparation of a concentrated saprophyte microflora in the spring from humus. It is done in the following way: a hundred-liter barrel is covered by a third with humus and poured into water heated to 25 ° C, then covered with sackcloth and wait for 6 days in the heat, stirring regularly.
Obtain the obtained substance through gauze and pour into a sprayer. When carrying out the prophylaxis, it is sprayed onto the freshly dissolved leaves of the grapes. The action is based on the penetration of the microflora under the scales of the kidneys and getting it onto the fungal spores, which are the nutrient for it. Treatment is carried out on a cloudy day or in the evening.
Repeated treatment should be done after seven days, and another - before flowering. With a strong development of the infection, after the flowering, it is necessary several times to treat the plant at an interval of a week.
Folk ways of protection
- Within a day, insist a half-bucket of ash in seven liters of water. Before processing, it should be diluted with water in the proportion: and add 10 grams of green soap. If there is not enough time, the ash can be boiled for 20 minutes.
- Pour water in the proportion of straw or fresh manure. Insist for three days. Dilute with three parts of water and process in the evenings for any time.