Grape diseases: signs, causes and treatment
Grapes – a culture that requires increased attention, especially if it is grown not in the south of Russia, but in the middle belt or in Siberia. Since the plant is heat-loving, it is quite difficult for it to survive in a cool climate, and lack of care, unsuitable soil and various diseases can destroy not only the harvest, but also the entire plant together with its leaves, stems and roots.
Grapes, like most other living organisms, are most often infected by infections transmitted from a diseased plant to a healthy one. This is how various viral diseases, fungi and harmful bacteria are transmitted.
In many cases, disease carriers in the vineyard are weeds and small soil pests: insects and rodents.
In infested bushes, any external factor affects their growth and development, be it soil fertility, soil composition, moisture, regularity of rainfall, etc. For example, diseased grapes simply rot during heavy rains.
There is also a non-infectious type of grape disease – it includes various mechanical damages, such as improper pruning, sunburn on the leaves, damage to the roots with gardening tools.
Fungal diseases of grapes.
The most common disease known to all farmers and winemakers is called powdery mildew (Sidium), or in common parlance, downy mildew.
This fungus affects the leaves, shoots and berries of grapes, creating yellow and gray spots on them. This symptom should not be ignored, otherwise you can be left on the plot not only without a crop, but also without a crop in general.
Fungi multiply in the soil, on fallen leaves and rotten berries, and are carried by the wind over large vineyards. Young leaves and berry bushes are more susceptible to infestation, older bushes are more resistant to this infection.
For prevention, experienced gardeners tie up shoots so that they do not lie on the ground; remove stems and excessive shoots; clean under vineyards, remove and burn leaves; and spray 5-6 times per season with preparations containing copper (1% Bordeaux mixture, copper oxychloride). The treatment is completed 3 weeks before harvesting.
Powdery mildew is treated by regularly spraying vines with fungicides. Zircon has shown good results. Another set of effective remedies: Strobi, Polyhom, Rodimol Gold.
Another dangerous fungus is Oidium. It is slightly less common, but the symptoms are almost the same as the first disease – gray spots on the leaves and berries.
The folk name for this disease is powdery mildew. If measures to prevent and treat this infection are not taken, the crop will be under serious threat. At first the berries will begin to burst, and in a few years the crop will disappear completely.
Prevention measures are no different from those for powdery mildew. The same measures will help protect the plant from infection.
For treatment, it is necessary to use solutions with the addition of sulfur preparations. Sulfur effectively fights the infection and saves the crop.
For a ready-made solution, you need to dilute 80 grams of sulfur in a bucket of water. You can also use sulfur powder with the addition of wood resin. Carbis Top, Tiovit, Topaz also help.
Anthracnose is the withering of the vineyard. Leaves and branches become covered with brown spots and wither. Most often caused by frequent heavy rains.
Treatment is the same as for mildew – chemical treatment and removal of damaged shoots.
If the disease has become chronic or prolonged, fungicides such as Cardozide, Fundazole, Polycarbacin, Horde, Pravur, Artceride, Abiga-Pic should be used. Absence of antifungal drugs should be done regularly at two-week intervals.
A disease similar to anthracnose is cordosporosis. When infected, the leaves become covered with olive spots and wither. Use a Bordeaux mixture to treat it.
Alternaria is a spring fungal disease. Symptoms are as follows: berries are covered with a heterogeneous white plaque, and other parts of the plant – gray or brown. Damaged berries quickly rot. Bordeaux liquid is effective in the fight.
Escoriosis (black spot) – This fungus forms black spots all over the plant. Leaves, fruits and branches turn black. Infected stems turn black, wither and die off, unable to hold the bunch. To save the plant, pruning and burning the damaged branches is necessary, and the plant can also be treated with Medea MA antifungal fungicide in early spring when the buds are just budding.
Apoplexy. This fungal disease affects the bush in the middle of the season, in hot weather. A white coating forms on the lower leaves. Because of the large amount of toxic substances released by the fungus, the plant can die very quickly, but there are cases when the disease manifests itself in a chronic form for several years. Arsenite helps against this fungus, but it is poisonous and should be used with caution.
Gray rot, white rot, black rot
Gray rot is a gray fibrous growth that affects all parts of the plant. It most often appears on the lower bunches of berries. It is a very dangerous disease that is difficult to treat. Medea ME, Titul 390, Potnitsa, Chorus, Anthracnol are recommended drugs. For prevention, lift the stems from the surface of the ground, graze the plant, remove weeds, and do not overdo the nitrogen fertilizer.
White rot is not much different from it. In this disease, it is mainly the berries that rot. A white coat, like a white horse, partially or completely covers the hands. This disease does not always indicate a fungal infection, sometimes it appears mechanically with damage to the plant. Treatment is the same as for Mildu.
Black rot. In this disease, the leaves and berries darken. When damaged, they become dark purple or black in color. The disease progresses quickly and spreads to healthy areas, and the rot increases. Anthracnose, topaz and fungicides containing copper are suitable for treatment.
Armillosis is a fungal disease that affects the roots and leaves of grapes. At first they turn yellow, and in the fall they grow yellow and brown fungi. Treat grapes with fungicides containing copper.
Verticillosis is a disease that progresses for five years. During the disease, shoots and leaves turn yellow. For treatment, the spraying of bushes with Fundazole is suitable.
Viral diseases of grapes
The most dangerous diseases of grapes are viral. Experienced winemakers and farmers know that in the case of a viral infection, the only correct way is to remove the bush, because such diseases are practically incurable. The disease is caused by small harmful bacteria that are transmitted by young seedlings or insects.
Such complaints are very difficult to identify because the symptoms are almost indistinguishable from fungal diseases or the effects of external damage to the vine, so preventive measures are recommended, such as:
- Planting only healthy “clean” seedlings
- Regular and periodic control of biting and sucking pests.
- Dig up and completely dispose of diseased plants
The most common viral diseases have the following names: leaf marbling, chlorosis (infectious), leaf vein necrosis, bloody mosaic, and short-stemming.
Non-transmissible diseases.
The most common disease caused by infections is chlorosis (glandular). It occurs due to unfavorable natural conditions, mainly developing in cold weather, but improper fertilization of the soil can also be the cause.
Too much alkalization and fertilization with nitrogen-containing substances also leads to chlorosis. Another common cause is iron deficiency in the soil.
The disease can be diagnosed by the following symptoms: grapes stop blooming, shoots become brittle and brittle, and the leaves change color and become very pale with a yellowish tint.
Chlorosis can be treated at any time by spraying a solution with iron preparations, but direct sunlight during treatment is excluded. It is recommended to use a solution consisting of 10 liters. Water and 100-200 grams of iron sulfate added. Leaves can be sprayed with iron sulfate, it strengthens their structure.
In addition to iron, it is recommended to fertilize the soil with vitamins, which include manganese, zinc and boron.
Pests of grapes
The danger to grapes is not only diseases, but also many different pests that weaken the plant and make it even more susceptible. The most dangerous are Reblaus, leafworm, grape moth, spider mite and others.
Diseases of the grapevine: description with photos, treatment
Photo: edaizm.ru
A separate vineyard is a very tempting species, but absolutely requires competent care. Even the most beautiful vine is not immune to diseases and problems. First of all, the leaves suffer from them – and this is a sure sign that an exchange is urgently needed. We’ll tell you what grape leaf diseases you may encounter and what to do about it!
Pimples and tubercles on the leaves
Yellowing is far from the only way a plant reacts to disease or unsuitable conditions. The spots on the leaves can vary in color, and sometimes they are structured. This makes it a little easier to find the cause because it’s mostly pests.
– Effort and bloat on the leaves are galls, which are caused by aphid larvae. Reborne is the main enemy of American and European grape varieties;
– Another parasite that leaves structured marks on leaves is the itch. It leaves nodules on the front of the leaf plate, while the back leaves depressions covered with hairs;
– In the worst case, the growths appear due to bacterial cancer on the leaves of grapes. It is accompanied by the formation of tumors and ulcers on all shoots. The disease is not treatable, so it is necessary to get rid of the damaged vine as soon as possible.
Leaves turn yellow and dry
If old vines turn yellow from the bottom up toward the end of the season, this is a natural process. But if young shoots turn yellow in mid-summer, you should be concerned.
– Chlorosis is a reaction of grapes to a lack of trace elements, especially magnesium. Less often there is a lack of iron, zinc and other useful components. In this case, a complex feeding is urgently required;
– grapes turn yellow due to lack of moisture and drying out, so adjust the watering regime;
– And if the leaves are yellow, but softened, it is a sure sign of rot, but already due to excess water;
– When the yellow leaves start to dry out at the ends, the grapes may be getting too hot. On hot days, the scorching sun is bad for most plants;
– Leaves turn yellow and wilt when there is not enough sunlight, since photosynthesis is directly dependent on sunlight;
– Irregularly scattered spots that form a mosaic-like pattern are a symptom of mosaic disease. This is an incurable virus that is still poorly understood, but most of its strains appear in the same way;
– Verticillium is another cause of grape leaves gradually turning yellow and falling off. At the same time, the shoots quickly wither, and the nodes begin to lignify irregularly.
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Brown spots on the leaves of grapes
Sometimes spots on the leaves take on a richer darker shade – orange, brown, brown. And there are reasons for this!
– Most often, small dark spots that appear on the leaves are a symptom of anthracnose. Later these spots will increase in number until the leaf dies;
– Bright and as if rusty spots indicate a disease of the same name – rust. This is another fungus that affects most garden crops;
– If the leaves of grapes first turned yellow, and then red and softened, it may be a symptom of rotting processes and even root rot. It is necessary to carefully inspect the root zone, reduce the watering regime and treat the plant with fungicides.
– Brown spots on the leaves combined with black spots on the shoots are a symptom of black rot. The same spots on the berries are deformed and appear droopy;
– Light brown spots covered with a velvety plaque with a pronounced shine are a sign of alternariosis. Later they turn into necrotic foci.
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Leaves of grapes turn black
If the leaves openly turn black, this is a manifestation of necrosis, and it is necessary to take immediate action!
– Phomopsis infection thrives on humid cool days, causing blackening of the leaves, the shoots turn white and the berries rot;
– Black, oval dots on leaves and all other parts of grapes are the first symptoms of black spot. The dangerous disease completely affects the vine, causing necrosis;
– Dark spots or light spots with black centers appear due to cercosporosis. The fungus safely overwinters in the ground and actively develops during flowering of grapes. Black spots can be seen even under the skin of ripening berries;
– If the leaves first turn yellow and then blacken, and the grapes wilt and fall off – try to feed them with potassium;
– Less often the cause of blackening is too loamy soil, as the roots of grapes do not take root well and suffocate in such dense soil.
White plaque on grape leaves
White plaques are a sure sign of fungal diseases, because they are actually future mycelium and spores.
– The first cause of the appearance is true mold, which spreads on hot, dry days. The bunch gradually turns a grayish color, and the berries burst;
– Mildew is the most common disease of medium width grapes. It is a false mold that is promoted by wet, cool days;
– If the plaque is initially gray, it can become a gray column. Grapes that have already formed, frown, are covered with the same plaque and rot;
– A white coating resembling cobwebs is left by the spider mite. Every gardener has encountered it at least once. Damaged leaves first turn yellow, and then turn red from the veins.
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Yellowed and light leaves
Sometimes the leaves of grapes do not turn yellow, but as if fading and wilting. We have already figured out the possible causes!
– If the young shoots are growing wilted, it means that the immunity of the grapes is weakened. Use special immunomodulatory drugs, otherwise it is a sure path to serious diseases;
– If the floor is too drained, the young shoots also become pale and weak. Therefore, it is extremely important to follow a feeding plan;
– Healthy adult leaves are first deformed and then covered with light spots due to white rot. Be sure to treat all cuts and wounds, as this fungus enters most often through mechanical damage.
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Leaves of vineyards curl.
If the leaves have started to deform, this is also an alarming symptom, so do not fool yourself. It is not just a matter of aesthetics, as the entire crop may die!
– The most dangerous variant is the virus of the same name, which quickly covers the entire vineyard. The harvest is cut in half, and the remaining grapes are much worse in taste and quality;
– Leaves may curl at best due to lack of oxygen. Therefore, do not thicken the grapes too much to save space and do not forget to thin the plantings regularly.
– If the leaves curl, wilt and dry out at the same time, it is likely that the grapes lack water;
– A lack of potassium causes the leaf plates to wilt, and phosphorus also causes the young leaves to darken. If the leaf bends like a boat, it lacks molybdenum. And when the edges curl and the leaves get smaller, zinc is the problem.
