Scab on potato: the reasons for the appearance and the ways of treatment

Scab on potato is a fungal disease that affects the tubers. Pathogens can stay in the soil for a long time, and get into the vegetable through pores or small wounds. Just want to say that the infected root can be eaten, but the damaged part is cut and thrown away. The danger of the appearance of scab is that the commercial and taste qualities of the vegetable are reduced, the level of vitamins, minerals and amino acids falls. If the loss of useful substances is 35% -40%, then the yield is reduced by half (in some cases, losses reach 60% -65%).

Favorable conditions for the development of the disease

Like any disease, the scab arises in certain cases. Among them are the following:

- soil pH is 6.1 - 7.4, that is, a slightly alkaline reaction.

- Air temperature 24 ° С - 29 ° С.

- Soil moisture content is within 50-70%.

- When applying lime and wood ash.

- When fertilizing the soil with manure. The danger lies in the fact that in the fight against scab, spoiled tubers are often used to feed livestock. Given that microorganisms are very stable, they pass through the digestive tract of the animal and go along with its excrement. Soil fertilization with such manure can cause additional infection.

- With an overabundance of nitrogen-containing fertilizers and calcium.

- With a lack of boron and manganese in the soil.

Preventative measures to prevent the appearance of scab

It is best to immediately create and try to maintain the conditions under which the causative agents of the disease will be uncomfortable. But if you still noticed on the tubers small bulging warts, then be sure to find out, How to get rid of scab potatoes. There are general tips for gardeners who can minimize the risk of developing the disease:

• Thoroughly inspect the planting material. Choose large tubers weighing 75-100 g, pretreated with a solution of boric acid (10 g per 9 liters of water).
• Deep sowing of root crops also reduces the risk of scab.
• After harvesting, it is necessary to collect all the remains (spoiled tubers, roots, stems) and destroy them.
• The planting site for potatoes must be changed, periodically sowing beans after it, which enrich the soil with nitrogen and disinfect it. Return the tuber culture to its original place in 4-5 years.
• Check the acidity of the soil (pH should not exceed 6.0). Otherwise, the culture can attack the potato scab. Treatment Chemical means Does not give results, but to reduce the risk of infection is not difficult. The pH can be adjusted by adding mineral fertilizers (superphosphate) under the tubers. Clearly observe the schedule of watering. The introduction of lime is only relevant when the soil pH is below 4.9. It is useful to mulch the potatoes with fallen pine needles, bring in sulfur (2.1 - 3.2 kg per hundredth) or gypsum (15-20 kg per hundred square meters).

These are only general recommendations. It is important for gardeners to know that there is a different scab on potatoes. The methods of struggle and the conditions of development can differ insignificantly, but in general the rules for eliminating the problem are the same.

Scab

This type of disease is more common than others. The causative agent is Streptomyces scabies. It develops well in sandy and calcareous soils, in conditions of high humidity and high doses of organic matter. The onset of the disease is easy to diagnose for small ulcers, which gradually grow and eventually become covered with a corky plaque.

Ordinary scab on potatoes Does not appear on all grades. The most powerful immunity to the disease is "Berlechingen" and "Priekul", as well as "camera".

Along with the general rules of planting and caring for culture, there are several additions. Before How to get rid of scab potatoes, Carry out preventive treatment of tubers - sprinkle them with "Nitrafen" or "Polycarbacin". It is very effective in combating the disease helps the germination of planting material in the light. Watering cultures begin immediately after deepening into the soil and continue until the trunk of the plant grows to 1.5-2 cm in thickness.

Scab powdery

The causative agent is Spongospora subterranea. Develops in too wet soil. And the lumps of the pathogen can mix themselves in the ground and reach the roots. Such a scab on potatoes Manifested in the form of warts of light gray color.

The skin of the tuber cracks at the site of infection, the disease spreads further. It is believed that such varieties as "lorch", "jubel", "cardinal" and "mazhestik" are practically not subject to the disease.

This disease is a potato - scab Powdery - affects the roots and trunk. Tubers are susceptible to additional infection with late blight and the appearance of dry rot. Planting material before sowing is kept in a solution of 40% formalin (proportion - 1: 200) for 6-7 minutes, then cover for a couple of hours with a tarpaulin.

Silver scab

In the beginning on the tubers there are spots of brown color or small areas resembling black soot. After peeling the peel of the potato, the stain becomes gray.

The causative agent is the fungus Helminthosporium solani, which multiplies rapidly at a temperature of 19-21 ° C and a humidity of 90-95%.

The disease is dangerous because the yield is very low. Affected tubers continue to lose weight even when stored, and the place of warts may appear gray rot. The yields on loamy and sandy loamy soils are more susceptible to the disease. Before planting, the tubers are etched. The treatment is also carried out immediately after harvesting before storing, using such preparations as Nitrafen, Botran, Fundazol, Celest or Titusim.

Rizoctonia, or Black scab

The causative agent is Rhizoctonia solani. Develops in conditions of high humidity. As a rule, infection occurs if the spring is late and rainy. Appears in the form of dark depressed spots or sclerotia, which are difficult to scrape off the surface.

Black scab on potatoes It is dangerous because it can hit the tuber even at the germination stage. Such shoots either perish, or appear on the surface with a lesion of the stem and twisted upper leaves. The causative agent is best on loamy soils.

This is one of the most unpleasant variants of the disease, since resistant varieties do not exist. In order not to reveal the black potato scab, the treatment begins with etching the tubers with such bacterial preparations as Integral, Planrys or Bactofit, as well as by means of Fenoram, Vivatax or Maxim.

Depth of planting: sandy loamy soils - 7 cm, loamy - 8-11 cm, peat - 12-13 cm. Maintain the average planting time, when the soil warms up to + 8 ° С. Prevents the appearance of rhizoctonia in the introduction of mineral and organic fertilizers in doses slightly higher than those recommended for this class.