Mildew on grapes is a dangerous disease. Treatment of mildew takes a lot of time and effort from a gardener, and this struggle does not always end with a gardener's victory. Fighting mildew is a long and stubborn process, as not all affected grape shoots respond well to treatment. The success of treatment depends on many objective and subjective factors: on the age of the vine, on the intensity of the measures aimed at fighting mildew, on the practical experience of the grower.
However, if you take the treatment of grapes seriously and use advanced methods of dealing with a dangerous infection, this fight will certainly be crowned with success. In the fight against mildew, the main thing is system and regularity. If the grower has already begun the struggle, in no case can you retreat. Purposeful work on the prevention and treatment of mildew will certainly bear fruit, and the plants will again become practically healthy.
Mildew grapes: what is the danger
Mildew is a fungal disease, in many respects similar to the common fungal infection called powdery mildew, affecting many crops. The danger of mildew is as follows:
- All the green parts of the plant are affected by the fungus and gradually rot,
- The disease develops rapidly, and it is rather difficult to fight it,
- Grapes are among the plants most susceptible to mildew,
- Plants affected by the mildew, like a magnet, attract a variety of pests and parasites.
Mildew usually appears in the event that if the grower is watering his plants too plentifully. Also one of the causes of this disease is high humidity, cold and humid weather in summer or spring. Plants that most of the time are in the sun are almost not affected by mildew. But the vines growing in the shade - in the "risk group". Most often mildew infects vines growing in the horticultural farms of the northern regions.
Mildew disease is manifested very clearly, and its symptoms can not be overlooked. At the first signs of mildew, it is necessary to take urgent measures, otherwise the disease will gradually spread to the entire vine and will inevitably lead to the death of the grapes. Characteristics of mildew:
- The presence of a characteristic yellowish, whitish or light gray on the leaves,
- The appearance of deformed berries, resembling a pear: elongated at the top and widened downwards,
- Drying the buds before they open,
- Wilting leaves
- Slow formation of new shoots.
The formation of characteristic plaque on the green parts of plants is the hallmark of many fungal diseases. However, the plant can be diagnosed with "mildew" in the event that a raid on the vine appears after rain or fog.
Any symptoms of mildew are alarming. This disease is dangerous primarily because the plaque on the leaves prevents the plant from breathing normally, blocking the access of oxygen. The leaves affected by the mildew literally “suffocate” from the fungus. The difficulty of normal "breathing" leads to the deformation of the leaves: they gradually turn yellow or become brown, in severe cases they even curl up into a tube. The plant begins to bloom later, the flowers dry quickly, the ovaries are not formed. Many inexperienced gardeners think that grapes suffer from a lack of mineral fertilizers, and they begin to feed the plant intensively.
But, reinforced dressing does not save the situationbecause the fungal disease continues to progress. The plant affected by mildew does not assimilate top-dressing in the proper volume, because it spends all the energy not on the assimilation of useful mineral substances, but on fighting the disease. For the same reason, the affected grapes fructify poorly, the berries ripen uncommonly, and their taste is noticeably worse. No grower is insured against mildew, therefore the symptoms of this disease should be known to all gardeners who grow various varieties of grapes in their backyard plots.
Some gardeners consider mildew a disease that simply infects the leaves, but does not pose any threat to the crop. This is a common misconception that has nothing to do with reality. Mildew significantly inhibits the growth and development of plants, preventing the formation of ovaries and the formation of full-fledged berries.
Mildew grape: treatment
Noticing mildew on grapes, you need to urgently take control measures. Measures to combat mildew on grapes can be different. Experienced winegrowers most often use following treatment methods:
- Spraying vineyards with special solutions. Acquire chemicals to combat mildew is desirable only in specialized stores. This method has one significant disadvantage - chemicals can get on the fruit and cause food poisoning in those who will eat unwashed berries. In addition, most modern chemicals do not erode for a long time. Therefore, if the vineyard was treated with chemicals, eating berries "straight from the bush" is strictly prohibited,
- Timely destruction and burning of the vine affected by the mildew. The leaves and stems of the grapes hardest hit by the mildew must be carefully cut with a pruner and immediately burned. If you just throw the affected shoots into the compost pile next to the vineyard, the fungus will not die, and re-infection will occur,
- Reducing the intensity of watering,
- Active loosening of the soil as prevention of stagnant fluids in the soil.
There were times when whole vineyards perished from the mildew. Now, of course, this does not happen, because modern wine-growers have the possibility of using industrial chemicals that stop the development of the fungus. However, in those regions where summer is cold and wet, even chemicals often do not help to completely get rid of the mildew. Especially for such regions breeders brought new varieties of grapeswith natural immunity to mildew. Grapes of these varieties are not affected by the mildew.
If the spores of a harmful fungus fall on the vine, they quickly die. If grapes in horticulture each year suffer from a mildew, perhaps it makes sense to destroy the affected vine and plant grapes that are immune to this dangerous disease. So many amateur gardeners do, and are satisfied with the result. Acquire such grapes preferably in nurseries. If you buy seedlings "from hands", there is a risk of being deceived, because visually a vine that is immune to mildew is no different from a vine susceptible to this infection. Saplings, impervious to the mildew, are quite expensive, but in this case it is better to overpay a little, than to lose the harvest because of the cunning fungus.
Grapes on grapes: control and prevention
It is better to prevent the appearance of mildew on grapes in a timely manner than to continue to treat the grapes for a long time and unsuccessfully, trying all new control measures. Mildew prevention on grapes is very important.. If you do not treat mildew on time, the problem will gradually worsen. When purchasing grape saplings in specialized stores and nurseries, you need to visually inspect the leaves and stems for damage by mildew. If the beginner grower noticed that the leaves of the seedling have a yellowish tint or seem slightly wilted, it is better to refrain from buying. Most likely, the plant is affected by mildew or another fungal infection.
To prevent mildew, it is necessary to fight pests and parasites. Harmful insects noticeably weaken the defenses of the vine, and a weakened plant becomes especially susceptible to various kinds of infectious diseases. Also, to maintain strength, plants need regular feeding with complex mineral fertilizers. During irrigation, you should not use cold water, as mildew most often appears precisely from the cold.
The vineyard should, if possible, be in the sun., and not in the shade, so next to the vines should not be spreading trees, creating shade. At first glance, these preventive measures seem fairly simple, but their use will help get rid of serious trouble.
Every beginner grower should know by heart major symptoms of mildew and other fungal infections. Information about diseases and pests of grapes can be found on the Internet and in specialized literature. The main thing is to be attentive and to take seriously any visual manifestations of trouble: yellowed leaves, deformed fruits, lack of ovaries.
In the care of the vine insignificant little things do not happen. If you treat the plants carefully and pay great attention to the prevention of infections, the vine will certainly thank for the care and attention to an excellent harvest. Mildew prevention is desirable year round.With the exception of winter, when the grapes enter a period of physiological dormancy.
Mildew is a dangerous disease affecting grapes and other cultivated plants. However, the use of modern advanced methods of protecting plants from the fungus allows the growers to successfully fight this disease and safely preserve the crop, even in cold and humid climates. The main thing is to start the treatment in time.
Picture of mildew on grapes: photo and description
The first signs of mildew are more often found on the leaves. At the beginning of the growing season, oily traces on their upper surface and an inconspicuous whitish coating on the back side of the leaf plate speak of the resettlement of the fungus. Moreover, the specific down, meaning sporulation, is better seen on the young parts of the shoots and leaves. Depending on the humidity and temperature of the air, the plant variety and the stage of development of the disease, the grape leaves in the middle of the shoot are covered with reddish or yellowish spots of various shapes and sizes.
With the defeat and spread of the fungus, the leaf plate necrosis begins, but the loss of foliage leads to a general weakening of the bush and a deterioration in the quality of the berries.
The ingress of fungus on the shoots is not accompanied by the appearance of oily spots. Here you can immediately notice the grayish or brownish traces of drying fabric. The fastest mildew of grapes, as in the photo, affects the inflorescences, the young parts of the shoots and the ovary, which has not yet reached the size of a pea. At the same time, in wet conditions, a specific white bloom can, in two days already, completely cover blooming brushes and ovary clusters, which turn brown and die off quickly.
Berries affected by the fungus at the stage of ripening or ripening darken, shrivel and dry. And on already ripe fruits mildew appears as pressed into the pulp, bleached stain in the region of the stem. Over time, and these berries become brown and showered.
Causative agent of grape leaf disease
Mildew or downy mildew is caused by a mushroom, in the form of spores wintering directly under the bushes of grapes, in the foliage which has fallen in autumn. Due to its resistance to frost, the causative agent of downy mildew safely waits the cold season, and even at a temperature of +8 ° C it is activated and spreads with the wind or raindrops on the green parts of the bushes.
Infection of a plant occurs when the zoospore finds a stoma on leaf tissue and is fixed. To understand the course of the disease of grapes, and how to treat the leaves and other parts of the bush affected by the mildew, it is important to determine the cyclical nature of infection and reproduction.
The duration of the reproduction period of a harmful fungus depends on the temperature, and its favorable outcome from air humidity. For the development of mildew on grapes, the optimal conditions can be considered as the temperature from 20 to 27 ° C and the period when the bush remains wet for more than four hours in a row.
At such times, the incubation period for the disease of grape leaves is dramatically reduced. During the season, the causative agent of the disease gives from 6 to 8 generations, while the incubation period on leaves and berries, becomes noticeably shorter by August. Until the temperature at night drops to +12 ° C, a whitish fluff appears above the stomata, which is a congestion of sporiferors. Getting with the wind to new areas of the plant, especially in wet weather, the sporangia release new zoospores, and the circle of infestation of grapes with mildew, as in the photo, repeats.
Protective measures against mildew on grapes
The gardener can take the first steps to protect against a dangerous disease even at the stage of laying the vineyard. Not all varieties have the same susceptibility to downy mildew. Even in the nineteenth century, it became clear that the fungus that caused serious damage to European plantations could not affect the yield and viability of American grapes. Moreover, in mildew-resistant plants, if spore penetration into the tissue occurs, then the further development of the fungus is not followed. In order not to observe lively the manifestations of diseases of grape diseases presented in the photo, and not to wonder how to treat the leaves and shoots, it is better to pick varieties that are rarely affected by mildew.
Today, breeders offer relatively powdery powdery mildew-resistant varieties of table, as well as universal, as well as technical purposes.
These plants include the Murom variety, which gives early dark-colored dessert berries, Muscat Dniester, Autumn pink grapes, Moldova variety, Magarach's Gift and other varieties.
But even when breeding resistant varieties without mandatory preventive measures to combat mildew on grapes can not do.
Winegrowers have noticed that powdery mildew often affects:
- young bushes and only seedlings planted from the school,
- plants that are regularly fertilized with products containing nitrogen but lacking potassium,
- landing with a thickened crown impervious to air and sun,
- bushes, under which weeds are preserved and the fallen leaves are not removed,
- vineyards in regions with a humid warm climate.
Although the main measures to combat mildew grapes include the use of chemical processing agents, it is possible to enhance the effect of such drugs by adjusting regular planting care.
Reducing the risk of disease bushes will help:
- the location of the tapestries along the direction of the winds prevailing in a particular area,
- wide inter-row spacing
- pruning grapes, providing airing of all shoots,
- regulation of the load on plants
- quality garter shoots, debris, chasing and pasynkovanie,
- timely removal of weeds and plowing or collection of fallen leaves.
But how to determine the processing time of the leaves of the vine from the disease, and how to treat the plant if the first signs of the disease have already appeared?
Spraying the grapes from mildew, as a measure to combat a dangerous disease
The timing of the chemical treatment of the vineyard with mildew is primarily dependent on the appearance of oily spots on the green parts of the plant. The effect of the protection will be greatest if by the time sporious spiders appear, the surface of the leaves, the inflorescences and the shoots will be completely covered with a layer of the preparation. This means that the treatment should be carried out shortly before the whitish, fluffy plaque becomes noticeable on the back side of the foliage.
The first spraying is done before the beginning of flowering, and if last year the defeat of the disease of grape leaves was serious, it is especially important to treat the vineyard as soon as the temperature rises above +8 ° C and the first heavy rainfall falls.
By choosing the time for the first treatment of the bushes, you can focus on the appearance of the first 3-4 leaves, and further spraying is planned based on the appearance on the vine and the development of the fungus.
Treatment of the bushes after flowering is aimed at protecting the ovary, after the calyx of the flower has fallen most susceptible to the disease. If the symptoms of the disease become visible when the grapes are actively flowering, the treatment is not delayed, but they are suitable, using products that do not contain copper. When the ovary is shown on the hands, treatments are necessary depending on the weather and the manifestation of the disease.
Bordeaux blend for treating grapes from downy mildew
The oldest and most proven remedy for mildew is Bordeaux liquid, which is a mixture of quicklime and copper sulphate solutions. In addition to downy mildew, the tool is used against anthracnose and other grape diseases, therefore it can be used as a measure of comprehensive prevention and treatment. For the manufacture of the mixture, you can take as a finished, mass-produced product, and use individual components.
If the treatment is carried out before budding, the concentration of the vitriol in the solution is 3%, but when spraying the leaves and green parts of the plant, this content of the active element will cause a serious burn.
Therefore, for the later treatment and treatment of grapes Bordeaux mixture immediately before the procedure, make a one-percent composition.
Из 5 литров горячей воды и 100 грамм медного купороса, тщательно размешивая, делают раствор. Затем в отдельной емкости в 10 литрах воды 75 грамм извести и также тщательно размешивают. A solution of copper sulphate is carefully poured into the milk of lime, the resulting product is mixed and filtered.
Bordeaux mixture for the treatment of grapes should be used without delay, it must be remembered that its protective properties are lost after the first rain, and therefore, the treatment will have to be repeated. When spraying, special attention is paid to the young shoots and the back side of the foliage.
Fungicides - drugs against fungal diseases
To process the Bordeaux mixture of grapes was more effective, the tool can be mixed with colloidal sulfur, a yellowish powder that does not harm humans, and has a bright effect against fungi and ticks. In this case, sulfur weakens the toxic effect of the copper drug, and the vine receives protection not only from mildew, but also from true powdery mildew.
Chloric copper oxide is the main active ingredient in fungicides such as Abiga-peak and Hom, used against oidium, mildew and anthracnose grapes. An effective drug from the powdery mildew causative agent is Delan.
Today, for the treatment of mildew, in addition to Bordeaux liquid, the grower has a number of effective drugs, both containing copper and based on other active substances.
Lime-sulfur decoction can be used as a substitute for Bordeaux mixture in the treatment of grapes or in addition to it. A brownish or dark orange liquid with a predominant odor of hydrogen sulphide, ISO, is also active against mites and mushrooms that infect grapes.
Alirin-B and Planriz are representatives of the class of microbiological agents recommended for treating vines against gray mold, powdery mildew and mildew.
Fungicide Strobe for grapes
The active ingredient of this modern means is fixed on the treated parts of the plant, is released within a few weeks and does not allow spores of the fungus to germinate, providing long-lasting and reliable protection of the vine from mildew and oidium.
Resistant to precipitation and not dangerous for Strobe grapes:
- not only protects plants from fungi that excite oidium and mildew, but also contributes to the maturation of the shoots,
- valid from 8 to 12 days
- can be used with other drugs.
At the same time more than three treatments of Strobe grapes per season are not allowed.
Ridomil Gold for the prevention of mildew on grapes
This systemic fungicide is prophylactically used against downy mildew and other grape diseases. The tool is slightly toxic and compatible with other drugs, and when alternating with contact-action fungicides, Ridomil Gold is most effective.
Processing healthy vines at risk of mildew infection is carried out in dry, windless weather, when there is no danger of burns for the bush.
The effect of spraying lasts from 7 to 10 days. The benefits of using Ridomil Gold on grapes are that:
- means, dried on the foliage and shoots, not washed off with dew and precipitation,
- protection extends to the untreated portions of the vine, including the increment formed after processing.
If there are signs of disease on the leaves of the vine, it is necessary to treat the plant with a fungicide of curative action and only then, after a week, apply Ridomil Gold.
Signs of mildew on grapes
On the foliage:
Primary signs of mildew: well visible yellow or brown spots on the leaves of the grape appear, seemingly oily in appearance. On young foliage, they are about the size of a penny, look like circles, on the old - angular patches of fungus, "stretch" along the veins.
After a time, a mycelium appears in the form of a white cannon on the back of the stained areas.
Gradually infected leaves curl, curl.
Inflorescences acquire unhealthy yellowness. Brushes curled, turn brown. Not formed dry out.
Fruits that have managed to outgrow the size of a pea, but have not yet had good sweetness, become bluish in color, then turn brown and look like a blown-out ball with visible wrinkles.
For more information, look like mildew grapes can be in the photo below:
And the following photo describes in detail the cycle of propagation of downy mildew:
The causes of the disease
Mildew - a formidable, rapidly spreading disease of European vineyards.
Develops due to fungus Plasmopar Viticola, which appeared in Europe in 1878 because of non-compliance with quarantine measures for wild grapes brought to French farmers by American seedlings phylloxera.
For two years, signs of infection of the vineyards with mildew were found not only in many vines in the south of France, but also in the plantings of Balkan and Caucasian wine-growers.
Fungal zoospores overwinter in the ground. On the vines fall along with sprays that form from raindrops hitting the ground.
Secondary infection from the sick area to the healthy, occurs both with rain and with the help of the wind.
Methods of struggle and methods of treatment
The proper effect is provided only by timely preventive measures, since when spore falls into the leaves, it is incredibly difficult to fight the disease.
The eradicating spraying of the soil under the vine should be carried out before the first spring rain, as soon as the vines are tied up and the soil is loosened. As a measure to combat mildew grapes use nitrofen, spreading 400 g per ten-liter bucket of water.
After tillage with a disinfectant, the soil is mulched. On the one hand, this will give an additional protective layer between the vine and the fungus hibernating in the ground, on the other hand, it will soften the blows of raindrops on the ground.
Treat grapes for mildew by foliar spraying with systemic fungicide Ridomilwhen 4 leaves appeared on the vine.
To protect the grapes from mildew:
In the fall burn all affected foliage, shoots (if the disease has already manifested itself on the vine).
For sanitization spray the soil: iron or copper sulphateBy making the composition according to the instructions, these folk remedies help to fight the mildew of the grapes and slow down the spread. In the spring, the soil is sprayed with a fungicide immediately after loosening the soil under the grapes.
Even mildew-resistant grape varieties are treated at least twice: first along the first leaves, then along the yet not flowered tassels, after having removed excess foliage (if any) from the bush.
Do not plant specimens without immunity to mildew, if you are afraid that you will not be able to spray them in a timely manner. Make sure the plants get enough potassium.
When mildew appears on grapes in the neighboring area, urgently need preventive treatment on their vines, so secondary infection is possible with the help of the wind.
Copper-containing solutions can be replaced with drugs: Ditan M-45, Mancotseb, Polycarbacin. This method will help to save grapes from mildew, which are sensitive to elevated copper content in protective preparations.
A month before the crop ripens, the treatment against mildew is stopped.
The most mildew-sensitive grape varieties:
Grape mildew is an insidious disease, only “waiting” for the gardener to make a mistake and delay with preventive measures against this American fungus. Therefore, if last year the disease took away a part of the harvest, then the next year, be vigilant. Do not let the spores, wintering in the ground and fallen leaves, which remain viable for 5 years, again “eat” your grapes.
Next, you can get acquainted with the video about the disease of grapes and how to deal with it and treatment with folk remedies:
Description and danger of illness
Mildew (or downy mildew) is one of the most dangerous fungal pathologies of European grape varieties. This disease hit the vineyards of England in 1834. They brought it along with new grapes from North America. For a short period of time mildew spread throughout Europe. The great decline in grape yields at the beginning of the twentieth century is also due to the appearance of downy powdery mildew.
Causes of downy mildew
The pathogen mildew belongs to the group of false powdery mildew fungi and is closely related to the blue mold of tobacco, peronospora of hops and late blight of potatoes. At the confluence of the male and female nuclei of hyphae, zoospores are formed, which can overwinter on fallen leaves of grapes without any special problems.
Throughout the summer and early autumn, oospores actively reproduce in the affected leaves. They have a very thick inner wall, so they easily tolerate cold and wet winters. At the beginning of April, when the soil is still quite wet, but the air temperature in the daytime is already at least + 8ºС, zoospores enter the active phase. They create one sprout tube each, at the end of which there is a single sporangium. If with the help of rain, wind or fog this sporangia falls on a grape leaf, it will break the shell and release more than 60 zoospores.
These small lumps of plasma begin to move in drops of liquid with the help of flagella. When they find the stomata, they form a tubule in it that grows inside the tissues and causes a primary infection.
The incubation period lasts from 5 to 18 days, depending on the season and weather conditions. As a result, oil spots are formed on the leaves, which indicates damage to the cells of the vine.
In the future, a shiny white fluff is formed, which is a large cluster of branched, tree-like sporiferous birds. Ovoid sporangia appear at their ends. At the slightest breeze of the wind, these sporangia fly everywhere.
How to deal with grape disease
Many gardeners who first planted a plant on their land, do not know how to treat mildew grapes, but at the same time there are two main methods of getting rid of this ailment: using chemicals and using folk remedies.
Most often for the treatment of downy mildew use a solution of copper sulphate. For spraying the leaves make a weaker solution, but if you have to spray lignified stems, then use a composition that is more saturated with copper sulphate.
- Burgundian or Bordeaux liquid. These solutions can be sprayed all parts of the vine. For the preparation of 1 percent Bordeaux mixture, freshly sour lime (120 g) of copper sulfate (100 grams) and water (10 liters) are used. To prepare a 3 percent solution, you need to take three times more of the vitriol and three times more lime, 10 liters of water. Mixtures of any concentration are also prepared (the amount of ingredients per 10 liters of water is calculated, knowing how many ingredients are needed for a 1% solution). To prepare the composition of the correct concentration, you need to use a nail: if the nail turns red when it is lowered into the prepared liquid, then the solution is highly concentrated, and you need to add a little water or lime. To prepare a 2 percent burgundy liquid you will need: blue vitriol (400 grams), soda ash (350 grams) and water (20 liters). To test the solution for proper preparation, you can use red litmus paper. When lowered into the solution, it should remain red.
- Chloroxide copper. Specialized stores sell 90 percent wettable powder (40-50 grams are diluted with 10 liters of water and sprayed with grapes).
- Copper silicate. To prepare this solution, you need to purchase copper sulphate (2 percent) and a solution of silicate glue (4 percent). Glue needs to be poured into vitriol and mixed (but not vice versa, otherwise an unstable suspension will turn out). In the end, you have a dark green liquid. The test for concentration is carried out by means of paper with a purgen. When lowered into the solution, it should remain slightly pink.
- Almost all the preparations based on copper are excellent help from mildew, in particular, and with the defeat of the grapes. Many solutions are sold immediately divorced: "Tsiram", "Zineb", "Kaptan", "Kuprozan", etc.
- Preparations based on lime and sulfur: “Planriz”, “Alirin-b”.
Treat powdery powdery mildew can folk remedies. You do not need to buy various chemicals, make strict solutions and check them for concentration. Here are some ways to treat traditional methods:
- Tincture of wood ash. For its preparation you will need: 1 kg of wood ash and 10 liters of water. The tincture is kept in a dark place for 7 days. After that, you can spray the leaves of grapes on both sides. The treatment is carried out at the first signs of illness. This solution can strengthen the root of a plant by pouring soil around the grapes on it.
- A solution of potassium permanganate. On a bucket of water add a teaspoon of potassium permanganate and spray the resulting solution with the leaves on the reverse side. While they are wet, they can be powdered with "powder" from wood ash.
- Dill can also be planted around the grapes. It helps in the fight against mildew, and in the case of infection - reduces the number of necessary treatments.
One of the main preventive measures in the fight against mildew is pruning old residues of the vine. It is burned along with leaves fallen in autumn. This can significantly reduce the risk of a new relapse in the spring. After that, it is necessary to carry out chemical treatment of the grape bushes and the adjacent soil, using a solution of ferrous or copper sulfate.
Preventive actions include several stages of the processing of grapes from mildew during the growing season, and spraying is best carried out in dry weather. Usually engaged in the processing in the early to mid-summer. The main stages of spraying:
- The best time will be a period when the inflorescences are a little loose. For spraying use Bordeaux liquid 1.5% or 2%,
- The second spraying is carried out after the flowering of the grapes. Use the same solution Bordeaux liquid, only less concentrated (1 percent),
- The third spraying is carried out after the size of the grapes reaches the size of small peas. Use the same solution as in the second spraying,
- The last spraying for the purpose of prevention is carried out 10-12 days after the third treatment. To do this, use a solution of copper oxychloride (0.4 percent). To prepare such a liquid, you must buy a package with copper oxychloride powder (40 grams). The entire contents of the bag is diluted in 10 liters of water and mixed thoroughly, after which you can begin spraying.
Mildew: the most resistant grape varieties
For a vivid example of the resistance of grape varieties to various fungal diseases, including mildew, a five-point scale was introduced:
- 0 points - full 100% protection against all diseases. At the moment, such varieties do not exist, but Dutch breeders have reported that they are working on this, almost impossible task.
- 1 point - the plant has high immunity and is almost not affected by downy powdery mildew. In most cases, these plants do not require prophylactic treatments. This category belongs to “Vitis Riparia” - a very fruitful grape variety. But it grows small clusters with small blue berries, so it is practically not used for dining purposes.
- 2 points - resistant varieties that can be affected only in very wet weather for a long time. After several treatments, mildew disappears without a trace. This category includes the following grape varieties: “Clairette Bulbasa”, “December”, “Arch”. Some agronomists put Arochny 1.5 points (from the list of the most delicious table varieties, it is the most protected from downy powdery mildew).
- 3 points - varieties of medium resistance need 2-3 single sprays throughout the growing season. Three grades received the following varieties: Bianca, Moldova, Victoria, Augustine, Timur, Arcadia, Talisman, Lora, Danko, Rusmol, Viorica, "Murom", "Riesling Magaracha" and others.
- 4 points - susceptible varieties that need special protection from the fungus. Spray need 4-5 times per season. With improper care dies from 25 to 50% of the crop. This category includes such varieties: “Rkatsiteli”, “Aligote”, “Cabernet”.
- 5 points - varieties that without timely chemical protection can lose from 50 to 100% of the crop. At the same time the plant can completely die. These varieties need to be sprayed every 1.5 - 2 weeks throughout the growing season. The five-point grades received the following varieties: “Kishmish Khishrau”, “Cardinal”, “Rizamat”.
Oidium: description and signs of the disease
Oidimum or ashtray is called powdery mildew - a common agricultural disease. Грибок у винограда особый — Унцинула. Первые признаки заражения оидиумом проявляются к маю:
- отдельные побеги начинают желтеть и отставать в развитии от своих собратьев,
- листочки скручиваются,
- green fabrics are covered with a greyish-white blot, which, when wiped by hand, emits an unpleasant odor,
- since June, it appears more clearly: both sides of the leaves seem to be sprinkled with dust or light gray ash,
- specific bloom covers inflorescences, and then clusters of grapes,
- the leaves dry up, the shoot tissues and the inflorescences also die off when the oidium forms are neglected.
Attention! Oidium grapes makes clusters unsuitable for food or for winemaking. Ripening berries are covered with dark spots, and then they crack and rot.
Infection with conidia (spores) of an uncinus can occur at any time. They are well tolerated wintering, being under the scales of eyes. Indispensable conditions for the development of fungal infections of grapes in spring is high temperature and wet weather, but without frequent precipitation. Spores germinate already at + 5 ° C, and best of all - at + 25 ... + 35 ° C.
The incubation period from infection with conidia to the growth of mycelium - 2 weeks. After infection, oidium will not stop either a decrease in humidity or a hot summer. Poor air circulation has a beneficial effect on the fungus: if the grapes grow in a poorly ventilated place or clusters are hidden behind an abundance of uncured foliage. Infection of the vine and the spread of the dispute continues until the fall.
How to deal with oidimum: prevention
Grape varieties are more or less resistant to oidium. Choosing a variety from the first category will make it easier for you to fight the fungus. However, a significant portion of tasty and productive grape varieties is just prone to being affected by an ounce. To prevent powdery mildew of grapes:
- Adjust agricultural techniques to influence the factors of disease development. Regularly and on time, carry out tying and breaking off the shoots, stumping, remove weeds to ensure the ventilation of the vine.
- Spray the vineyard with an infusion of ash: half a bucket of dry matter per 7 liters of water, infused for 1 day. Before processing, add 100 g of rubbed soap for better adhesion of the solution.
- Treat the grapes with a solution of manure (1: 3), infused 2-3 days before fermentation. Before spraying, strain the mixture and dilute once more with water (1: 3).
Attention! The best time for the prevention of oidimum - the early growing season. The procedure is desirable to repeat a couple of times.
Of the chemical preparations, sulfur-containing products are good. This element acts as a toxin on spores. To prevent illness, the concentration of such agents as Cumulus DF or Tiovit Jet is 40 g per bucket. Spray 3-4 times during the season at intervals of at least 10 days.
Oidium Vine Treatment
To combat oidium use the same drugs as in the prevention. Increase the concentration to 100 g per bucket if signs of infection are already detected. True, this can only be done before or during the bud break. Late can not.
Also for the processing of grapes in the early stages proved to be drugs Chorus, Skor, Topaz. At low summer temperatures, Strobe works. Caratan and Talendo can be used after flowering vines. If the powdery mildew is not the only fungus on the branches, Switch will help.
If the clusters have already begun, it is better to refuse chemicals. A solution of potassium permanganate has a short-term effect of slowing the growth of the oidium fungus. Dilute 5 g per bucket and spray in the vineyard. At the very least, this will allow to gain time and allow healthy berries to ripen.
Description of mildew. How to deal with a fungal infection
Mildew - false or sticky mealy dew. Its pathogen is the spores of the plasmopar viticola fungus. They begin to actively develop as soon as the summer rains begin. When damp and cold, the fungus can destroy the vine with a crop in a matter of days.
The first sign of mildew - oily spots on the leaves. In wet weather, they are covered with whitish bloom from the bottom of the sheet plate. Gradually, green, yellow, brown areas appear, which eventually dry out. The disease easily spreads to the inflorescences and clusters of grapes. The latter may partially dry out or even become completely covered with powdery powder.
Outcome defeat mildew:
- not ripening grapes, richly covered with whitish mycelium,
- reducing the frost resistance of the vine,
- disease of the plant and, as a consequence, the absence of berries in the next season.
Prevention of mildew (downy mildew of grapes) - spraying. Schedule the first procedure for April, as soon as the waking vine was tied to a support. Use Abiga-pik, Oxy, Bordeaux mixture. Crop the land around the plant and cover it with mulch.
A second spraying of the grapes is required after the appearance of 4-6 leaves. Use Omega-peak, Polycarbocin, Homoxyl, copper oxychloride or Polychrome. Bordeaux mixture in this period is ineffective. Add colloidal sulfur to the preparations at the rate of about 8 g per 10 l. Repeat the treatment after the rains.
Final spraying before flowering spend drugs Tiovit Jet Topaz. In case of a disease, process the grapes at intervals of 2 weeks using Quadrice, Ridomil Gold, Cabrio Top or Champion.
In the fight against any fungus, combine fungicides so that the harmful organisms do not develop immunity. The main protection of your grapes from oidium and mildew is a good year-round care and healthy neighborhood with other cultures.
- 1. Listen to the article (soon)
- 2. Writing
- 3. Mildew or Oidium
- 4. Treatment
- 4.1. Control measures
- 4.2. Treatment
- 4.3. Prevention
- 5. Preparations (fungicides)
- 6. Folk remedies
- 7. Mildew resistant grape varieties
Mildew Disease - Description
The mildew of grapes is manifested by lightening of the affected tissues: oily, yellowish transparent spots the size of a small coin form on young leaves, and the spots on the old leaves have angular outlines and are located mainly along the veins. Soon on the underside of the leaves under the spots appears white powdery downy - mycelium. Spots spread to all green plant organs - tendrils, shoots, ridges, inflorescences and young berries. The affected inflorescences turn yellow and curl, and then turn brown and dry. The berries turn blue, darken and shrink - they become as if leathery and unsuitable for food and winemaking. Disfigured mildew leaves fall prematurely, and the diseased tops of the shoots dry.
The rate of development of the disease depends on air temperature: at 20–25 ºC, mildew signs appear on the fourth or fifth day, and if the weather is cooler, the symptoms will appear later. The disease progresses in conditions of high humidity. Damage from the disease in the absence of protective measures may amount to 50% of the crop.
Mildew or oidium
In addition to mildew, a common disease of grapes that can destroy up to 80% of the crop is oidium, or powdery mildew. These diseases differ among themselves by the fact that on the upper side of leaves affected by oidium, not oily spots appear, but a whitish coating. Under this bloom, if you erase it, you can find brown spots. Another distinctive feature of oidium is the smell of rotting fish.
Measures to combat mildew.
If you grow European varieties of grapes, in any case you have to take action against mildew. The fight against mildew includes first and foremost the use of chemical agents, however, prevention of the disease and measures for the care of grapes are also important. If the vines are planted spaciously, it contributes to good ventilation and quick drying of the bushes, and, consequently, reduces the risk of spreading infection. It is very important to timely remove stepchildren and excess shoots, tie up growths and regularly remove weeds.
Processing grapes from mildew.
Mildew grapes are treated with copper-containing antifungal agents. There are drugs among them that are washed away by the first rain, and there are those that have a long duration of exposure - up to three weeks. A significant part of fungicides contains copper, which is the most suitable and inexpensive means of fighting mildew, however, some grape varieties do not respond well to treatments with copper-containing preparations, especially during the flowering period.
How to treat mildew on those grape varieties for which the use of copper is contraindicated? There are a number of anti-mildew preparations called organic fungicides. They do not contain copper, and yet do an excellent job with real and downy mildew. Their basis is made up of such active substances as captan, maneb, zineb, mancozeb, thiram, cynos and others. These drugs are marketed under various names.
Today, there are commercially available mildew fungicides, which are a combination of organic fungicide with sulfur or copper, and sometimes with both substances. The presence of sulfur in the preparation allows to destroy the infection in just one treatment, and the combination of copper with organic matter mitigates its damaging effect on copper-sensitive grape varieties.
In the fight against the strong defeat of mildew, such drugs of contact and systemic action, like Ridomil Gold, Champion, Quadris, Cabrio top, have proven themselves.
Mildew disease - prevention.
Significantly facilitate the fight against mildew on grapes help preventive measures. The first preventive treatment is carried out in the spring, immediately after the vines are tied to a support. They cultivate grapes, land under bushes and aisles, after which the site is mulched to suppress the spread of infection. As preparations for the treatment of used solutions Bordeaux mixture, Oxyhoma, Abigak-peak or other drugs prepared in accordance with the instructions.
The following prophylactic treatment is carried out in the period of 4-6 leaves. Since the Bordeaux mixture inhibits the development of young growth, it cannot be used at this stage. For spraying using drugs Polykhom or Polycarbacin. In 10 liters of treatment solution 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 oidium and even from ticks. In addition, sulfur stimulates the formation of leaves.
Before flowering, the grapes are treated with Tiovit Jet, Topaz or Actellic preparations, 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 the contact-systemic drug, which include Tanos, Ridomil Gold, Acrobat other.
Try to alternate fungicides, since one of the main drawbacks of some of them is the development of resistance, that is, addiction to them fungus. That is why each of the drugs can be used only once per season.
During the fall of the leaves, they are pruning the bushes of grapes, after which all the leaves, cut off 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.
Preparations for mildew (fungicides)
Of the many fungicidal drugs most often used in the fight against mildew are:
- – Abiga peak - copper-containing contact fungicide of a wide spectrum of action, designed to combat fungal and bacterial diseases of vegetable, industrial, fruit, ornamental and flower plants. Moderately dangerous substance
- – Acrobat MC - a systemic-local fungicide used to combat Alternaria and blight of potato, mildew of grapes and cucumber peronospora. Dangerous substance
- – Bordeaux mixture - a broad-spectrum fungicide designed to protect vegetables, berries, fruits, melons, citrus, flower and ornamental plants from a complex of diseases. Dangerous substance
- – Copper sulfate - copper-containing contact fungicide of a wide spectrum of action, used to combat diseases of ornamental, fruit, berry crops and shrubs. Moderately dangerous substance
- – Oxy - systemic contact fungicide of a wide spectrum of action for fighting fungi of the class Oomycetes. Dangerous substance
- – Ridomil Gold - system-contact drug for the control of Alternaria, blight and other fungal diseases. Dangerous substance
- – Kvadris - a broad-spectrum fungicide for the protection of grapes, indoor and outdoor cucumbers, tomatoes, onions, potatoes, as well as sports lawns from a complex of diseases. Dangerous substance
- – Convertible top - the combined fungicide of a broad spectrum of activity, specially developed for protection of grapes at the same time against oidium and mildew. Moderately dangerous substance
- – Thiram - contact pesticide used to protect plants from phytopathogenic fungi. Drugs based on Tiram are assigned to classes 2 and 3 of danger to humans,
- – Polyhom - a complex action fungicide that effectively protects plants from diseases such as moniliosis, peronosporosis (mildew), late blight and other diseases that have a fungal nature. Moderately dangerous
- – Polycarbacin - systemic fungicide of protective and therapeutic action, which is used to combat fungal diseases of vegetable and fruit crops. Moderately dangerous.
Mildew resistant grape varieties
Among the grapes 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 positively affects the quality of the crop. Such stability is evaluated on a five-point scale of Gusfeld. For example:
- - grade 0 is given to varieties that are not damaged by the disease at all and, accordingly, they do not need protection from mildew,
- - 1 point - for varieties in which no more than 5% of the leaf apparatus is affected, therefore there is also no need for chemical treatments,
- - 2 points deserve varieties that are affected by mildew by no more than 10%, and they also do not require chemical protection,
- - 3 points receive relatively durable varieties that require no more than two preventive treatments per year, because without spraying with fungicides you can lose up to 25% of the crop,
- - 4 points for mildew-susceptible varieties that should be treated with chemicals 4-5 times a year, since without fungicide treatments, yield losses can be 50%,
- - 5 points for highly susceptible varieties whose mildew can reach 100%, and therefore chemical treatments should be carried out after each rain.
Almost all Euro-Asian grape varieties are highly susceptible (5 points), new Euro-American varieties and other more complex hybrids are resistant to mildew at level 3, and sometimes 2 points. Of the mildew-resistant varieties, the best are:
- – Golden steady - highly productive frost-resistant table variety of early maturation, which is almost not affected by mildew, oidium and gray rot. Berries of this variety are of medium size, white with a golden blush on the sunny side, juicy flesh, fresh harmonious taste,
- – Dniester pink - frost-resistant productive variety of late ripening with dark pink berries of medium size with dense pulp of simple taste,
- – Buffalo - cold-resistant American variety with black oval berries of medium size with a bright strawberry flavor and a tart aftertaste,
- – Pineapple - Another American variety, characterized by high winter hardiness and relative resistance to mildew. The berries in this variety are large, yellow-green, the skin is thick, the pulp is mucous, palatable, with an aroma that resembles the smell of pineapple,
- – Cardinal - an early ripe Californian grade with large berries weighing 8-10 g of very pleasant taste with nutmeg aroma,
- – Mascot - frost-resistant early-medium high-yielding table variety with large (12-16 g) white berries of harmonious taste, which acquire when fully ripe, nutmeg flavor.
In addition to those described, grape varieties such as Honey Gift, Zaporizhia Gift, Alex, Bajen, Noble Muscat, Nistru, Original and others are resistant to mildew.