Mildew, or downy mildew of grapes - the most common and harmful disease of European crop varieties, affecting all terrestrial organs. The disease is caused by the fungus plasmopara vitikola, which in 1878 was brought from North America to France and eventually spread throughout the vineyards of Europe.
It was the appearance of this disease that caused the decline of European viticulture in the late 19th and early 20th centuries.
Mildew of grapes is manifested by the clarification of the affected tissues: on young leaves, oily, yellowish transparent spots the size of a small coin are formed, on old leaves the spots have angular outlines and are located mainly along the veins. Soon, a white powdery fluff appears on the underside of the leaves under the spots - mycelium. Spots spread to all green plant organs - antennae, shoots, ridges, inflorescences and young berries.
Affected inflorescences turn yellow and curl, and subsequently turn brown and dry. The berries turn blue, darken and shrivel - they become as if leathery and unsuitable for food and winemaking. The leaves disfigured by mildew fall prematurely, and the diseased tops of the shoots dry out.
The rate of development of the disease depends on the air temperature: at 20-25 ºC, symptoms of mildew appear on the fourth or fifth day, and if the weather is cooler, symptoms will appear later. The disease progresses in conditions of high humidity. Disease damage in the absence of protective measures can be 50% of the crop.
In addition to mildew, a common grape disease that can destroy up to 80% of the crop is powdery mildew. These diseases differ from each other in that on the upper side of leaves affected by powdery mildew, not oily spots appear, but a whitish bloom. Underneath this plaque, if you rub it off, you can find brown spots. Another hallmark of oidium is the smell of rotting fish.
If you grow European grape varieties, you will have to take action against mildew anyway. The fight against mildew involves, first of all, the use of chemicals, but prevention of the disease and measures for the care of grapes are also important. If the vines are planted spaciously, this promotes good ventilation and quick drying of the bushes, and, therefore, reduces the risk of spreading infection. It is very important to remove stepchildren and excess shoots in a timely manner, tie up growths and regularly remove weeds.
Grape mildew treatment is carried out with antifungal agents containing copper. Among them there are drugs that are washed off by the first rain, and there are those that have a long exposure time - up to three weeks. A significant proportion of fungicides contain copper, which is the most suitable and inexpensive remedy for mildew control, but some grape varieties do not respond well to copper treatments, especially during flowering.
How to treat mildew on those grape varieties for which the use of copper is contraindicated? There are a number of anti-mildew medications called organic fungicides. They do not contain copper, and yet they do a great job with real and downy mildew. They are based on such active substances as captan, maneb, tsineb, mancozeb, tiram, cinos and others. These drugs are marketed under different names.
Today mildew fungicides are commercially available, which are a combination of an organic fungicide with sulfur or copper, and sometimes both. The presence of sulfur in the preparation allows you to destroy the infection literally in one treatment, and the combination of copper with organic matter softens its destructive effect on copper-sensitive grape varieties.
In the fight against a strong defeat of mildew, such drugs of contact and systemic action as Ridomil Gold, Champion, Quadris, Cabrio top have proven themselves well.
Preventive measures can greatly facilitate the fight against mildew on grapes. The first preventive treatment is carried out in the spring, immediately after the vines are tied to the support. The grapes, the land under the bushes and the aisles are cultivated, after which the site is mulched to suppress the spread of infection. Solutions of Bordeaux mixture, Oxychoma, Abiga-peak or other preparations prepared in accordance with the instructions are used as preparations for processing.
The next prophylactic treatment is carried out during the appearance of 4-6 leaves. Since the Bordeaux mixture inhibits the development of young growth, it cannot be used at this stage. For spraying, use drugs Polychom or Polycarbacin. In 10 liters of solution for processing, prepared in accordance with the instructions, it is advisable to add 80-90 g of colloidal sulfur, which will protect the grapes not only from mildew, but from mildew and even mites. In addition, sulfur stimulates leaf formation.
Before flowering, the grapes are treated with solutions of Tiovit Jet, Topaz or Actellik, and after flowering, when the fruits are already the size of small peas, it is necessary to spray the bushes and the soil under them with a solution of a contact-systemic drug, which include Thanos, Ridomil Gold, Acrobat other.
Try to alternate fungicides, since one of the main disadvantages of some of them is the development of resistance, that is, the fungus gets used to them. That is why each of the drugs can only be used once a season.
During leaf fall, grape bushes are pruned, after which all leaves, cut shoots and branches are burned. Before sheltering for the winter, the grapes and the soil under it are treated with a solution of 1 kg of salt or 200 g of urea in 10 liters of water.
Of the many fungicidal preparations, the following are most often used in the fight against mildew:
If you find signs of downy mildew on grapes at the very beginning of its development, you can try to destroy the infection using folk methods that are more gentle than fungicides and pesticides. For example:
Planting dill around the vines will help you keep mildew treatments to a minimum, but be careful not to overgrow the dill.
Among the grape varieties, there are less and more resistant to downy mildew. Resistance to mildew allows you to reduce the number of treatments of grapes with pesticides, which has a positive effect on the quality of the crop. Such stability is assessed on a five-point scale of Gusfeld. For example:
Almost all Euro-Asian grape varieties are highly susceptible (5 points), new Euro-American varieties and other more complex hybrids have a resistance to mildew of 3, and sometimes 2 points. The best mildew resistant varieties are:
In addition to those described, grape varieties such as Gift of Honey, Gift of Zaporozhye, Alex, Bazhena, Muscat noble, Nistru, Original, and others have varying degrees of resistance to mildew.
Growing healthy grapes is not easy. Proper cultivation will help prevent many grape diseases. You should control weeds, watering, loosening the soil and fertilizing, and then everything will work out. The disease, getting into the juices of the plant, affects the tissues, which can lead to the death of the culture. Let's consider the most common diseases, their prevention and how to treat grapes from diseases.
Oidium on grapes (or powdery mildew)
A dangerous fungal disease for grapes that leads to loss of harvest. In the event of a harvest, the quality of the wine significantly deteriorates. The pathogen overwinters on damaged shoots and in the buds. The first signs of the disease appear in the spring. Massive damage to plants begins at a temperature of + 20 ° C. The wind easily spreads spores and infects healthy plants. Outwardly, it looks like this: the disease affects the leaves in the form of gray-white spots, which gradually combine into a common plaque. The leaf curls up and dries up. Young shoots grow poorly. Flowers bloom and fall off. Affected berries stop developing and dry up.
Prevention in the folk way: put the mown grass in a heap and bring it to a state of mold. Fold into a bucket, add water and stir. Insist for a day. Strain. Spray the entire vineyard with the prepared solution. The procedure can be carried out throughout the summer.
How to treat oidium: fungicides Topaz, Tiovit Jet, Quadris, Flint Star help with the disease.
Phomopsis or black spot
The disease is common in all grape regions. The pathogen overwinters in plant tissues. In spring, spores are spread by wind, rain, insects. The disease enters the plant through mechanical damage. The defeat looks like this: round red-purple spots spread along the shoot. Affected branches become brittle and break easily. On young shoots, up to 60% of the buds die! Berries are affected at the ripening stage. With a strong black spot infestation, you can lose up to 50% of the crop. Moreover, the perennial wood of the bushes dies off, which leads to the complete death of the culture!
Fighting the disease is difficult, as it is a chronic disease. If an affected area is found, the branches should be cut and burned.
Mandatory early prevention in the phase of swelling of the kidneys up to the phase of 4-5 sheets: preparations based on copper - Bordeaux liquid, Copper sulfate, Copper oxychloride.
To treat the disease, use chemicals: Quadris, Topaz, Tiovit Jet.
Rot on the grapes
Grapes can be affected by another type of fungal disease is rot: white, gray and black. This disease destroys the fruit. Gray and black rot are active after prolonged wet weather, while white rot is active in hot dry weather. Gray rot covers ripe berries with a mouse-like bloom, and does not touch green ones due to the acid content in them. Black rot appears in the form of brown spots, which gradually merge. Over time, the berries turn black and fall off.White rot appears on berries in places received after sunburn. Black grape varieties are affected.
Folk remedy in the fight against rot: dilute 5% iodine 1 ml per 1 liter of water. Treat with a solution for the first time, when the berries are still gaining size, the second time during ripening.
In the fight against rot, use drugs: Quadris, Ridomil Gold, Horus or Switch.
Most often rubella appears on heavy soils. It develops differently every year - not equally intensively. This fungal disease primarily affects leaves and other green organs. At the very beginning, the disease manifests itself on the lower leaves, in the form of spots: yellow spots appear on white grapes, and brown on red ones. Symptoms are similar to mildew infestation, but over time, the spots grow over the leaf and the leaf dries up. Affected berries do not accumulate enough sugars and lose their taste. The causative agent hibernates on fallen leaves.
It's important to know! Rubella spreads significantly during the period of weak mildew development, i.e. during the period when the number of treatments with anti-mildew drugs decreases.
Tinctures will help with the disease: - Mix milk with water in a ratio of 1:10. - mix soda with liquid soap 40 g per 10 liters. - dissolve 5 g of manganese crystals in 10 liters of water. Spray the plants with ready-made solutions, to choose from or alternate.
Preparations for the fight against rubella: before flowering Tiovit Jet, and later the same as with mildew.
Mildew on grapes (or downy mildew)
Dangerous fungal disease. Harms the entire green part of the vine - leaves, shoots, buds, mustache, inflorescences and berries. Spores of the fungus overwinter on fallen leaves. The defeat of healthy plants occurs in spring, in the presence of young leaves and a temperature on the soil surface not lower than + 11 ° С. The onset of the disease is characterized by the manifestation of greasy, yellow spots on the leaves. In a day, a mealy bloom will form - these are spores. Spores are spread to other plants by the wind. When the disease reaches the berries, the berries turn brown, shriveled. Exacerbation period: May 20 - June 13, June 23 - 30, June 15 - August 7.
Traditional methods against mildew: pour 1 liter of dry wood ash with 10 liters of water. Insist a week. Strain and add 50 g of laundry soap to the solution. Spray with the mixture every 10 days, until the leaves fall off.
Recommended chemical treatment: Ridomil Gold, Quadris.
The best way to prevent illness is through prevention.
Prevention of grape diseases
- Choose only trusted suppliers of grape seedlings
- Buy grape varieties adapted to your growing conditions (climate, soil, temperature)
- Carry out agrotechnical measures on time: in the morning or in the evening
- Monitor the condition of the soil under the seedlings. Collect all fallen leaves and weeds in the fall and after pruning. Disinfect the tools used with a solution of laundry soap.
- Use only balanced fertilizers
- Control watering and adjust for rainfall. The soil should be moderately moist
- Make a schedule of activities, so it will be easier to control the growing process.
Biologicals for grape diseases
General biological control measures Such protection involves the use of biological agents.
Prepare a humus concentrate in spring: fill 1/3 of humus in a 100 l barrel, add warm water. Withstand the solution for a week. During this period, bacteria will multiply. Strain the concentrate through cheesecloth so as not to clog the sprayer. Spray during the growing season (from the budding phase to the formation of brushes) once every 10 days. Carry out 5 - 6 sprays. Such a measure will significantly restrain the development of a destructive pathogen.
This is a ready-made base solution that must be diluted with (not chlorinated!) Water according to the instructions. Spray the bushes and add to the watering of the soil. Processing should be carried out according to plan - the first in April, the second when budding. For the treatment of bushes, the solution should be less concentrated than for the soil. Strong concentration has a depressing effect on the formation of the crop. Effective microorganisms (Baikal EM-1) improve soil structure, germination and growth, and increase resistance to diseases and pests.
General recommendation for the use of chemicals
Processing with chemicals should be carried out with the onset of an air temperature of + 13 ° C and completed no later than 1.5 months before harvesting. Read the instructions before using the drugs.
General prevention and treatment at the initial stage of the disease. Treatment of grapes from diseases
- Dilute 3% copper sulfate according to the instructions and carry out processing in the spring before bud break, and in the fall after harvesting.
- Process 1% Bordeaux mixture solution in three stages: before flowering, after flowering and before fruit ripening. Bordeaux mixture is a harmless drug - it prevents disease. It is recommended to use some chemicals next to this drug, for example, Ridomil Gold. This drug has a complex effect on several types of rot.
When choosing a method of struggle, prevention should be put in the first place, and if the moment is missed, treatment is indispensable. We hope our tips will help you cope with the difficulties!
Causative agent grape disease mildew is an Plasmopara viticola - a representative of peronosporous oomycetes, the life cycle of which includes the flagellate stage - zoospores. They spread and infect plants in a droplet-liquid environment, therefore, the active development of infection directly depends on the amount of precipitation and air humidity during the growing season of grape bushes. Dry and hot weather conditions suspend the development of this disease, however, with the first rains, the process of plant infection resumes.
Oospores of the pathogen mildew hibernate, as a rule, in fallen leaves and plant remains of grapes. They also form inside the leaves in summer and closer to autumn. In spring, when the air temperature rises above 8 ° C, oospores Plasmopara viticola germinate and form one sprouting tube each having a zoosporangium.
It is from such a zoosporangium that, when favorable conditions occur, a sprout tube appears, which, by introducing into a plant, causes primary infection. After an incubation period of 12 to 18 days, asexual sporulation occurs, which causes secondary infection of plants. The air temperature in the range of 21-25 ° С, as well as the presence of droplet-liquid moisture for at least 2 hours, contribute to the activation of secondary infection. Its incubation period on grape leaves is 9-18 days, depending on the season and weather conditions. The risk of infection of the berries exists until their size reaches 6–8 mm, after which the infection with the fungus is carried out only through the stalk.
A group of diseases caused by harmful bacteria. General signs: specific spots and growths on different parts of the plant. Spreads from infected plants and soil. Carriers can be pests of grapes: nematodes, aphids, drosophila flies.
The bacterium Agrobacterium tumefaciens E. Smith et Towns infects the stem and vines of grapes through frost holes and other damage to the bark. Large growths form on their surface. Within 2 years, the plant completely dies. The bacteria from the cancerous tumor also enter the soil.
Diseases of grapes - photos of bacterial cancer
This disease cannot be treated. The plants are removed and burned, and nothing is grown in their place for at least 2 years.
Acetic bacteria are the cause of the disease. The berries on the bunches gradually turn brown, burst and rot. There is a sour vinegar smell. Such a crop is not suitable for consumption and harvesting.
Bacterial disease - sour or vinegar rot of grapes
Infection can be detected in the early stages, when a swarm of insects can be seen around the affected berries. All affected berries must be removed, and the plants must be treated with Fitoverm and 1% Bordeaux liquid. Dusting with sulfur, bait with poison for parasites, and other methods of dealing with wasps are also effective.
The seriousness of the problem lies in its rapid spread, especially given that it is difficult to ensure a full-fledged fight. There is always a danger of bushes rotting.
Other problems awaiting the gardener:
Attention! The best prognosis is when the disease is detected at an early stage. So the vine itself will suffer less, but the harvest can still be considered lost. This is due to a decrease in taste.
The main rule in the fight against diseases: It is easier to prevent a disease than to cure! Therefore, when cultivating grapes, preventive treatments cannot be avoided.
Compliance with preventive measures will help ensure that your plant is fully protected from mildew and other diseases. So, initially it is necessary to regularly check the vineyard for symptoms of a particular disease. When found, the affected areas must be immediately eliminated and burned, and the healthy part must be carefully processed.
After the final harvest, you need to get rid of all plant residues, since a virus could remain on them, which, over time, is able to move to healthy areas of the grapes. Before wintering, the planting must be treated with iron sulfate for prevention. In summer, especially in hot weather from +8 to +30 degrees, you need to carefully monitor the watering of the plant. In no case should excess water be allowed, since heat and high levels of humidity are the most favorable conditions for the development of fungal diseases. At the same time, during watering, water should not be allowed to enter the grape foliage and shoots, otherwise there is a risk of the plant getting a burn.
A healthy seed variant must be used for planting grapes.... It is also recommended to take a closer look at those plant varieties that are highly resistant to various diseases, including mildew. This will not be able to protect your vineyard 100%, but with good care and preventive measures, it will significantly reduce the likelihood of disease occurrence.
In addition, you need to get rid of weeds and harmful insects, which are often carriers of various diseases, on a regular basis.