Many problems bring potato disease to gardeners. Photo, description and treatment of scab (rhizoctonia), dry rot - the subject of our conversation. After all, potatoes are a staple food in many countries. It is easy to grow it on a personal plot, which makes it popular with gardeners. But potatoes are susceptible to many diseases. The main pathogens are various fungi, bacteria, viruses. Prevention is almost the only remedy. Many diseases can be prevented if preventive measures are taken in time or treatment is started at the initial stage.
Scab or rhizoctonia is a common potato disease
Scab, a description of potato disease
Scab, blackleg or rhizoctonia is a fungal disease of a potato that occurs wherever it is grown. The causative agent of the disease is the fungus Rhizoctonia Solani, which can be in the soil, even when there are no potatoes. The parasitic activity of the pathogen is determined by temperature, humidity, and the state of the host plant. The pathogen of rhizoctoniasis infects not only tubers, but also other parts - stems, stolons, roots.
Rhizoctonia is one of the most common fungal diseases of potatoes in home gardens, called the black leg or black scab. It causes especially great damage under favorable conditions for the development of pathogens.
Rhizoctoniosis - manifests itself in the form of a black scab, rotting of the eyes, sprouts, dying of roots, as well as a “black leg” of stems in wet weather. At the beginning of the development of the disease, lesions on the stolons, roots, stems have a reddish-brown color. When they mature, they turn into gross ulcers with cracks. If the ulcers are significant, then they can encircle the stem, interfering with the normal movement of juices and carbohydrates throughout the plant. Thus, symptoms of the disease can be seen on the ground and on the tuber.
On infected stolons, stems above or below the surface of the soil, sunken brown ulcers of various sizes and shapes can be seen. These ulcers can be of a zoster nature - in this case, the plant dies sooner or later. On such stolons, young nodules cannot be born, develop.
Black plaque is the most visible sign of the disease. In this phase of the disease, the Rhizoctonia Solani fungus forms growths from dark brown to black, as if the potato were stained in the ground. But this is not land, these are the so-called sclerotia, which are on the surface. They are irregular in shape, ranging from small flat spots to large convex spots. Although these structures adhere tightly to the surface of the tuber, they do not penetrate inside and do not spoil the taste of potatoes.
However, if such potatoes are used as seed material, sclerotia will inhibit the development of planted potatoes - they can even destroy it. This is because, during the growing season, the Rhizoctonia Solani fungus infects the root system, the base of the plant stems. The movement of nutrients from leaves to young tubers is disrupted. Upper leaves curl along the main vein. It appears that they are affected by aphids.
The main source of infection is seed. Sometimes heavily infected potatoes are not even able to form stems. This symptom is called "no top", it can be confused with the same symptoms as growing from physiologically old seeds.
Potato scab, photo, description and treatment
The treatment of rhizoctonia, black scab requires an integrated approach, knowledge of each stage of the disease. One of the most important means of combating the disease is the acquisition, planting of seed material of only high quality, which is not infected with pathogenic fungi.
An effective way to fight diseases is prevention - presowing light germination of tubers. The introduction of rotted manure, superphosphate, potash fertilizers reduces the negative effect of the pathogen.
Potatoes are best planted after corn, beets, beans, peas. Weak plants are most susceptible to the disease, but it practically does not infect sprouts of germinated tubers. Therefore, it is very important to sprout potatoes before planting, so that before planting, it would be possible to discard potatoes infected with rhizoctonia. It is equally important after the rain to loosen the ground so that a crust does not form. In this case, no favorable conditions are created for the fungus that causes the disease.
Processing potatoes before planting with a 1.5% solution of boric acid also protects it from infection with rhizoctonia. The volume of the solution should be prepared at the rate of 50 ml per 1 kg of tubers.
The disease is most pronounced in cold and wet seasons. Microspores are stored in potatoes or in plant debris for up to two years. When cutting seed material in the presence of infected tubers, for example, when growing potatoes from eyes, infection of healthy ones is possible. Therefore, do not forget to remove diseased bushes from your site. Cut the tops before digging the crop so that the rhizoctoniosis bacteria do not have time to get to the tubers from the leaves. Be sure to germinate the seed material to remove diseased potatoes in time. Try to be sure to warm it in the sun, dry it, plant green seeds before putting it into storage.
Dry rot, potato fungal disease
Dry rot of potato, photo, description
Dry rot is caused by several species of fungi of the genus Fusarium, hence the name dry fusarium rot. If you, periodically inspecting the potatoes in the basement, find dry, pressed spots on the peel, this indicates that it is affected by dry Fusarium rot. These spots are the first symptoms of the disease. As a rule, they appear on the surface of the tuber. Gradually, the flesh under the stain dries, becomes rotten. The skin is wrinkled, torn. In the voids formed, mycelium grows, that is, mycelium with maturing spores.
Mushrooms of the Fusarium genus of several species cause dry rot. Depending on the species, the spores are similar to grayish-white, yellowish or pink convex pads.
Where could this potato disease come from? This can be said at the location of the spots.
If dry rot appeared on tubers only from the side of the stolon end (a small dent on the potato, where the stolon was attached), then the whole soil of your garden is infected with this fungus. Let us explain: the stolon is a lateral underground shoot, at the end of which a potato tuber ripens. This is a potato “umbilical cord” by which a growing nod receives nutrients from a bush.
And if potatoes are affected from different sides, then the reason is improper harvesting, poor storage. Most often, the disease begins to rage where there were injuries, incisions, lesions of late blight or scab.
Your basement may be too warm. At elevated storage temperatures, dry rot develops rapidly and spreads. As you know, the optimal storage temperature of potatoes is 1-3 degrees above zero.
Dry rot on potatoes, methods of control, prevention
Most methods to deal with this disease of potato are aimed at preventing injury to tubers when harvesting or storing. Preventing damage to the surface of potatoes will help to avoid infection.
If the soil is contaminated in your area, you should not plant potatoes there for at least five or six years. Siderata or crops sown on such a field will eliminate the fungus from the ground, but this may take several years. Therefore, the main thing is to prevent soil contamination. And this can only be achieved by careful selection of seed material.
Can I eat infected potatoes?
Is it possible to eat potato infected with scab? Or should they be thrown away? Not at all. Select them, remove the damaged parts. Feel free to fry potatoes or mashed potatoes for dinner.
Conversely, potatoes affected by dry rot are not recommended. Even if you have a tuber affected only on one side, you should not eat, supposedly healthy, the other half. Throw away the whole tuber without any pity.
To keep your potatoes healthy, pick or buy high-quality seed material for planting. Pay attention to the characteristics of the variety, to resistance to a particular disease. Dig up potatoes intended for future planting earlier than for food and storage, as the longer it will be in the ground, the greater the likelihood of infection. Try to observe crop rotation.