Alternariosis fungal disease of grapes. Diseases are susceptible to the aerial parts of a grape bush: spotting and necrosis of leaves, petioles, shoots and berries.
Conidium and mycelium of the fungus spend the winter in the bark of grapes, in the fallen leaves and in the soil. Most often the disease manifests itself in the second half of the growing season.
If infected with alternariosis, the grape leaves become covered with spots.
Alternaria disease or olive spot grapes
The spots may be irregular and rounded in size about 1 cm. The color of the spots on the leaves is light yellow, then darken and dry. The edges of the leaves dry, the leaf turns gray and takes on the appearance of burnt. External signs of damaged leaves resemble oidium. In order to accurately determine which disease was encountered, it is recommended to rip off the affected leaf and place it in a container with water and cover. Leave in a warm place for 2-3 hours. In case of infection with alternaria, an olive-colored patina will appear on the sheet, the same plaque can be seen on the sheet in wet weather. Shoots are covered with brown or brown spots. Berries are covered with silver metallic bloom.
Why is it dangerous
Alternariosis significantly reduces yield, if the disease is run. Harmfulness - the annual death of up to 60-70% of the eyes in the autumn-winter period (the usual natural death of 5-10% of the eyes). It was determined that the pathogen spreads to other vineyards located from the diseased at a distance of 200-300 meters. Alternaria is most dangerous for berries during storage. Berries become wrinkled and get an unpleasant taste.
Description and Symptoms
In the last decade, Alternaria only strengthened and became more resistant to external influence. The damage of grape crops, which are characterized by the influence on the vegetative mass and yield, is monitored everywhere.
Vineyards may be affected:
- Alternaria alternate which in turn provokes the development of Uni Blanc disease. The disease begins to manifest itself at the end of the spring period, when on the grape foliage one can find yellowish spotting of small sizes, up to one centimeter. If you tear one affected leaf and look through it into the light, you can see the spotting more pronounced. In the period of rains and dampness in the lower part of the sheets can be considered the formation of olive moldy plaque. If this happens, then the edges of the affected leaf shrink, it becomes gray and looks burnt. The same plaque can be formed not only on the leafy part of the plant, but also on the berries and crests. At the end of the summer period, when the maturation of the woody part of the plant occurs, other symptoms of the disease can be traced. Aging of green shoots occurs in an uneven manner: some of them remain green for a long time, and then simply become whitish, instead of browning. In winter, the bark lightens, it acquires an off-white shade and staining occurs. Also, a characteristic feature of this disease is reduced winter hardiness of the plant, and when planting new seedlings there is a problem with their rooting - they massively perish.
Causes and pathogen
As indicated above, Alternaria is a fungal disease that can affect the entire ground portion of grapes. Due to such optional parasites as Alternaria alternate and Alternaria tenussima, weakened plants are colonized. The development of the fungus is triggered by high air temperature and humidity. Over the past 10 years, the disease has become particularly resistant to weather changes and has spread to different vineyards, while the severity of alternariosis has increased.
Treatment of Alternaria
When the plant was defeated, it is necessary to fight to start treatment so as not to aggravate the situation and stop the spread of the fungus to other plants. Consider how and what to treat Alternaria grapes, to get the highest quality result and stop the parasitism of the fungus. There are many treatments that are in their own way good and effective. Among them are the popular methods and methods of treatment with the help of chemicals.
Folk methods more effective in preventive purposes, rather than curative, but they are also often used in order to reduce the parasitic effect of the fungus on plants in combination with chemical processing.
Korovyak in the form of infusion. This tool is prepared at home, it is necessary to use 3 kg of manure per 10 liters of water. Infuse the mixture for 3 days, then pass through the filter and apply to spray the ground part of the plant. This tool is very popular among growers, as it does not contain harmful substances and is safe for people and plants.
Potassium permanganate To prepare the solution, use 5 g of product per 11 l of water. It is necessary to pay special attention to the preparation of the solution in order to prevent severe burns in the plant.
Milk. For cooking means you need to use 1 part of milk and 10 parts of water. The resulting liquid is processing the ground part of the plant. Due to the influence of sunlight and high air temperature, the active development of lactic acid bacteria will occur, which will help to suppress the growth of the fungus that causes Alternaria.
Laundry soap with soda ash. For the preparation of this tool should be used 30 g of soda and 30 g of soap per 10 liters of water. Due to the characteristic film that is formed after applying the product to the plant, the fungus will not be able to overcome the barrier and will suffer from the alkaline effects of soda.
In order to get rid of Alternaria grapes, it is most effective to treat the plant with chemical agents.
It is definitely necessary to begin treatment when you find clear signs of Alternaria, which will mean the disease is flowing into a severe form.
Well help in this case processing Bordeaux mixture. For the treatment to be effective and not to harm the plant, it is necessary to take a responsible approach to the preparation of the mixture.
It will be correct to prepare a mix, observing the rules:
- Breeding of copper sulphate and lime should be done in different vessels.
- The mixture of lime and water is thoroughly mixed and filtered.
- The solution of copper sulfate should be filtered and a little lime is added.
Processing can be performed regardless of the stages of the growing season. Usually made up to 6 treatments per season. After processing, you can begin to eat fruits after 20 days after processing.
Very effective and popular means for processing grapes is considered "Trikhodermin". It is necessary to prepare means for use according to the instruction on packaging. Treat this tool is necessary during the period when the first opening of the leaves of the vine. It is important to take into account the air temperature during the treatment period, it should not be below 15 ° C.
After treatment with Trichodermine, you can resort to the use of other chemical preparations, which are sprayed with vineyards with an interval of 2 weeks between different treatments.
Effective means that can be used in the fight against Alternaria, are: “Skor”, “Kvadris”, “Rapid Gold”.
In order to avoid infection of grapes with Alternaria, it is necessary:
- timely remove organic residues,
- spray a solution of Bordeaux mixture of 2%,
- to feed regularly with mineral fertilizers, which will enhance immunity,
- observe the proper agricultural practices on vineyards.
In order to avoid infection with Alternaria, grapes are recommended to acquire varieties that are resistant to the disease. At the moment, specially bred varieties that are able to resist these fungi does not exist. But given that Alternaria is very similar to other diseases, such as black rot and altracnosis, it is advised to choose grapes that are well opposed to these diseases. You can resort to planting:
- Cabernet Sauvignon,
- "Amur Breakthrough",
- "Amur Triumph",
Description of the fungal disease
Fungal disease spreads due to the hot and humid climate. It is easy to identify the affected shoots - they are covered with silver or brown spots from above. Some newcomers to viticulture confuse this disease with oidium. Accurately determine infection with Alternaria can be placed grapes in a moist chamber. Shoots quickly covered with a velvety olive bloom with the so-called kinidiyami. The leaves are first covered in the center by necrosis with light spots. After that, getting into moisture, the fungus begins to spread actively.
When Alternaria affects the fruit, they are covered with a touch of metallic shade. Also, the berries become tasteless, shrink.
Spores are released only through the cuticles. Alternariosis is very dangerous both for berries and in the process of storing grapes.
To combat Alternaria it is enough to fulfill the following requirements:
- keep the high agrofone
- destroy post-harvest residues of grapes,
- at the first symptoms, spray the bushes of grapes with a 2% solution of Bordeaux mixture,
- try to quickly harvest
- storing grapes in the recommended temperature conditions, adhere to the desired humidity.
External symptoms of the disease, causes of occurrence and spread
With increasing humidity on the back of the stains an olive gray bloom forms. Because of it, the disease is called olive blotch. Developing, the fungus dries and twists the leaves.
The danger is that the pathogen passes to the fruit, from which they crack and acquire a terrible taste. The affected shoots do not ripen, so they can not overwinter.
Another causative agent of this species, Alternaria tenuissima, is dangerous for varieties for hybrid forms of American-European origin. Most of them were derived as resistant to diseases of the grape - mildew, oidium, gray rot. The place of these pathogens is alternarioz.
Preventive measures against Alternaria grapes
To prevent the spread of the disease can be mechanical, agronomic and chemical methods.
2. Burning plant residues of grapes and dry weeds.
2. The use of EM - drugs, for example,
Emmies and other effective microorganisms increase soil fertility and suppress pathogenic flora. In the case of infection, treatment is carried out exclusively by chemical means.
Biological and chemical methods of control and treatment of the disease
If the symptoms of the disease are uniquely characterized by Alternaria, it means that the disease has spread so much that it is time to connect the "heavy artillery," that is, chemical drugs. Substances that are effective against this disease in terms of the range and duration of treatment coincide with drugs from black spot and altrachnosis.
- Copper sulfate.
- Bordeaux mixture.
Note! Preparation of Bordeaux mixture is performed in a specific sequence:
- Copper sulphate and hydrated lime are diluted in different containers.
- The lime slurry is thoroughly mixed and filtered.
- Lime milk is poured into a filtered solution of copper sulfate in a thin stream.
Tip # 1. Before combining both liquids, it is better to carry out a test compound of a small amount of substances. If the liquid does not coagulate, then everything is done correctly.
Bordeaux mixture is important to properly prepare.
Trichodermin - the most common biological fungicide against Alternaria. The treatment is carried out in the same time as against black spot, when the first leaves are opened, with an average daily temperature of +120 - 150. At a later time, chemical preparations are used at intervals of 10 to 14 days.
Treatment plan for grapes for Alternaria:
After tying up the vine, before bud break.
When the first sheet appears
Tip # 2.When processing grapes against altranosa, it is important to use sprayers, which is convenient to irrigate the underside of the leaves. Surface application of liquid does not give results.
Disease resistant grapes
For the treatment of grapes from Alternaria, it is better to use sprayers with a small radius of spraying.
One of the ways to avoid alternatives is the selection of varieties resistant to the causative agent. Specially bred forms that oppose only this pathogen has not yet been derived. Since the timing of infection and methods of control coincide with black rot and altreknozom, it is better to choose hybrids that confront these pathogens.
So far there is no information about the infection of the Alcrannose hybrid forms of Amur grapes, such as:
- “Amur Breakthrough” (or “One”),
- "Amur Triumph",
In the area of risk of infection is to refrain from planting European varieties:
- Pearls Saba,
- Queen of the vineyards.
- Alphonse Lavalle,
- Muscat Hamburg,
- Muscat Hungarian,
- Must be white.
Category: Questions and Answers
Question number 1. How long can you get rid of Alternaria?
Question number 2. What to plant next to the grapes to protect against the disease?
Experienced winegrowers surround the planting with plants that emit specific substances that repel insects. Those, in turn, damage the grapes and carry pathogens. Helping out pests will help:
Marigolds and other useful plants deter pests and significantly reduce the spread of disease.
Question number 3. Can neighboring vines and other crops become infected?
Unfortunately, they can. The causative agent of apple alternaria in living trees was first discovered precisely in the orchard. Studies that study the biological changes of the fungi of this group have not yet been completed. It is not yet known exactly what other cultures Alternaria can parasitize. In any case, definitely not worth planting grapes next to the apple trees.
Question number 4. Is Alternariosis Dangerous to Man?
Fungal diseases of plants are not transmitted to humans. Discomfort in digestion can cause berries infected with Alternaria. But this can hardly happen. The taste of diseased fruits is so nasty that it is impossible to eat them.
Serious gardeners mistakes in the prevention and treatment of Alternaria
Error number 1. Selection of grapes that are resistant to Alternaria.
In climatic zones, where the disease has been actively spreading lately, it is better not to plant the rash of European - American origin:
The varieties listed in varying degrees, resist the most common fungal diseases - oidimum, mildew, gray rot. Unfortunately, they do not have immunity from Alternaria.
Error number 2. Incorrect, thickened pruning.
Weakens grapes and creates favorable conditions for the development and spread of pathogens.
Error number 3. Surface treatment bushes.
The causative agents of alternatoriosis are based on the back of the leaf and on the shoots below them. Sprayed on the top of the sheet of the drug, the fungus does not reach. Thus, such a spraying is a waste of time and labor, the result is zero.
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