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Potatoes are almost the most popular vegetable, grown by more than 80% of summer residents. It is he who is most often affected by a variety of infections. Bacterial, fungal or viral diseases of potatoes can destroy most of the crop even before harvesting. Even when storing a healthy-looking potato, there is a risk of spoilage. In this case, the infection from the tuber can go to other vegetables, stored together with potatoes.
To protect yourself from loss of harvested and stored crop, it is important to detect signs of infections in time. The most common belong to three groups:
- fungal infections - late blight, alternaria, scab, cancer, phomosis and fusariosis;
- viruses - mosaic and necrosis;
- bacterial diseases - brown and ring rot, black leg.
Each group is represented by several harmful infections that can reduce potato yield 3-5 times. According to statistics, fungal diseases of potato cause the greatest losses of crop.
The most common infection is late blight. The losses of a crop at infection by it can reach 60% and more. External manifestations of late blight begin to appear in the flowering phase. The lower leaves of the potato are covered with brown spots that grow over time, which eventually cover the entire nest. In rainy weather, a white coating appears on the underside of diseased leaves - the spore-bearing tissue of the Phytophthora infestans fungus. Tubers infected with late blight are covered with dark spots. At the same time, the fabrics remain dry and firm.
When sick plants appear, it is important to practice crop rotation of the potato, because the spores of phytophthora persist in the soil, on the remains of the leaves and in the tubers.
Infected with blight of tubers is not recommended for storage, as in this case there is a risk of losing the entire crop, including vegetables that are in the same room as the sick potatoes.
Another dangerous infection is potato cancer. In the areas where the cases of infection of potatoes are fixed, a quarantine regime is introduced. This fungal disease affects the tubers and stolons of plants, leaf blades and stems. On the tubers in the immediate vicinity of the eyes there are growths that increase in size. Despite the absence of obvious rot, tubercle cancer patients can not be stored.
To avoid the appearance of disease, it is important to choose resistant to it varieties. When there is a cancer of the potato, it is necessary to destroy the infected tubers. The field on which the foci of the disease is found can not be sown with potatoes for a minimum of 3 years.
This disease can destroy the entire plant, including stems and tubers. Most often its victims are medium late and late varieties. The first signs of infection can be recognized by the appearance of brown spots on the leaves that appear before the flowering of the plant. Over time, the diseased leaves turn yellow and die. Foci of infection on tubers can also be easily recognized by brown color and irregular shape. If the potato alternaria potion affects most of the tuber, the surface of these spots may look wrinkled.
Like this disease manifests itself and the phomosis of potatoes, with the only difference that the spots on the tubers acquire a grayish shade, and their size does not exceed 2-5 cm in diameter. Another significant difference is the timing of infection. If the alternaria penetrates into the young stems of the plant, then the phomosis affects the stems in the second half of the vegetation. Ripened by them, spores along with rainwater fall into the soil, where the tubers become infected.
Before laying down for storage of planting material from the site where the plants infected with phomosis and plantaria were found, it is important to conduct the dressing of the tubers. Infection can be contained and compliance with the temperature in the basement.
Large losses of harvest can be suffered and when they are affected by various types of scab: ordinary, powdery or silvery. Ordinary scab develops only at high soil temperatures and low humidity. Sick tubers are covered with dry, slightly stained dark spots above the surface of the skin. Stems this kind of scab does not strike.
The same applies to plants and powdery scab of potatoes. It affects only the underground part of plants. At the initial stage, round spots with a diameter of 6-7 cm, covered with a white coating, appear on them. Over time, these areas are destroyed, and in their place remain red sores. Unlike ordinary scab, the powdery show activity only at high humidity.
Silvery scab affects only the tubers during storage. As a result of infection, they lose a lot of moisture, which makes them light and excessively dry. To plant such a potato is not suitable. It provokes an outbreak of the disease with high humidity (more than 90%) and a temperature above 3 degrees.
To avoid mass infection of tubers by any kind of scab, it is important to observe crop rotation of potatoes. It is important to pay attention to and prepare the planting material: the dressing before storing for storage will prevent re-infection of tubers and soil.
Black potato leg
The disease develops as a result of the defeat of the plant by the bacteria Pectobakterium. The source of infection are diseased potato tubers, plant remains in the soil. It is often spread by insect larvae. It affects almost all parts of the plant at any phase of development. Chronic character acquires in dry conditions. Potato bushes begin to hurt immediately after emergence. First the leaves turn yellow, then they curl up and dry up. The bush quickly fades, the stem becomes soft and easily pulled from the ground. On the tubers the black leg of the potato manifests itself as dark rot in the part of the stolon.
Another disease of potatoes, in which the yield loss can reach 50% - fusarium wilt. Most often it develops in conditions of high temperatures and humidity. At first fusariosis can be taken for the diseases of potato tops, photos of which often flash in specialized publications. Infection affects the leaves of the plant: the upper becomes light, and the edges of the lower become anthocyanin shade. Over time, they lose elasticity and wither. On the lower part of the stems there are spots covered with a touch of orange or pink. Getting into the soil, the infection affects the tubers, causing their decay.
To avoid the death of the harvest from fusariosis, it is enough to mow down the infected tops and remove all plant residues from the site. Only after this, you can start harvesting potatoes.
How to treat potatoes from fungal infections?
It is necessary to fight with fungal diseases of potatoes at the stage of preparation of planting material. Before processing the potatoes with a solution of boric acid or copper sulfate, it is important to take away the tubers undamaged by the infections. During vegetation it is necessary to constantly monitor the condition of the tops. At the first signs of disease, it is necessary to remove the affected plants, then to process planting with a 2% solution of copper sulfate, Hom or Maxim.
Fungal infections often fall into the soil with not completely rotted plant residues and manure. It is important to exclude such phenomena, since this will reduce the labor costs for processing crops by special means and increase the amount of harvest. To avoid infection of tubers during harvesting, it is necessary to mow the tops in advance and remove plant residues from the site. Tubers, damaged during transportation and storage, should be consumed in the first place, since they are most often affected by infections.
Also important is the crop rotation of potatoes. Most fungal diseases exist in the soil for 2-3 years. If there are no cultures on this territory that can become carriers of infection, it spontaneously disappears.