As the plant develops, it is exposed to infections, pests, which leads to a change in appearance, inhibition of growth. If spots appear on the leaves of grapes, natural causes, such as deteriorating environmental conditions, should be considered. To restore the decorative properties of a plant, various means (biological, chemical) are used, the choice depends on the cause of the development of negative processes.
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Factors affecting the condition of grape leaves
If the plant is cultivated under suitable conditions, then the appearance of pigmentation (spots of a different color), deformation of the leaves is facilitated by microorganisms (fungi, bacteria, insects, mites, etc.). Among the most probable reasons are:
- Yellow spots - they appear as a result of infection with downy mildew. The disease is called mildew. Symptoms: Small yellow spots on the upper side of the leaves. White spots can be seen below. They are somewhat reminiscent of powdery mildew: plaque appears, lesions gradually increase, spread, as a result, the whole bush becomes ill. Leaves fall off, fruits shrivel, darken.
- Brown spots are a sign of anthracnose. This is a fungal disease, so it spreads quickly. The main symptom: the edges of the spot are darker than the middle. Not only leaves are infected, but also stems. The green mass is thinning, the fruits fall off.
- Light spots: white, gray, ashy. This is how powdery mildew manifests itself. Gray bloom quickly affects the leaves, then they fall off. The yield of such bushes is reduced, since the fruits are also susceptible to powdery mildew.
- Blackening of the leaves, the reason is the development of Alternaria (fungal disease). At first, small areas are affected, but soon the leaf completely darkens. The disease covers the entire bush, including the fruit. A metallic sheen appears on them. Increased humidity contributes to the development of Alternaria. Another likely cause of leaf blackening is excoriasis, or black spot. The disease develops in poorly ventilated areas, with high humidity. Helps to reduce yields.
- Reddening of the leaves. Sometimes this is a consequence of a natural process (the symptom appears when the conditions of the plant are violated). But also red spots are formed against the background of the development of rubella disease. Probable factors contributing to this: potassium deficiency in the soil, arid climate, low air temperature. Another reason is grape itch, but in this case the spots are small, and bulging plaques are visible on the back side.
- Rust. The disease is caused by a fungal infection.
How to eliminate signs of grape disease?
The choice of the remedy depends on the reason that caused the deterioration in the appearance of the plant, the decrease in yield. Ways to fight infections:
- The means Delan, Hom, Kurzat, Kuprikol will help remove yellow spots. They are used to prevent mildew disease. In case of infection, the vine is treated with a solution of copper sulfate (concentration 1%).
- Brown pigmentation of the plant. In this case, the means Previkur, Arcerid, Fundazol, Skor are used. An alternative option is a solution of copper sulfate, but the concentration should be higher - 3%.
- Powdery mildew. A solution of colloidal sulfur is used: 90 g per 10 l of water. Processing is carried out before and after flowering. You can use the funds Topaz, Ordan, Hom, Kurzat.
- When the foliage is blackened, a solution of copper sulfate (3%) or a biological product Trichodermin is used. Black spot disease must be fought with a less concentrated solution of copper sulfate - 1%.
- Rubella. Processing is carried out with potassium nitrate (1%). If the cause of red spots is a tick (itching), apply the acaricides Pyridaben, Amitraz.
- Rust. The treatment is carried out twice with a break of 14 days, using the Strobi fungicide. Recommended scheme: 5 g per 10 liters.
The vineyard should be planted in well-blown areas, pruning should be done in a timely manner, and organic debris should be removed from the aisles (in large vineyards).
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