Potato fusarium: description, causes of the disease, measures against it

The fungal disease fusarium can have a detrimental effect on potato bushes not only during the growing season, but also during potato storage, which can lead to a loss of 40% of the crop or more.

Therefore, it is important to know about the causes and course of this disease in order to fight it effectively.

Description

Fusarium is dangerous not only because of the extent of crop damage. Because of its slow development, it is not always detected in time. In addition, if there were diseased potatoes on the site, the mycelium of fungi can remain in the soil for several years, which is why it is not recommended to grow vegetables on the site for 7 years.

Causes of the disease

The causative agent of potato disease is the fungus Fusarium oxysporum. Fusarium is usually the result of several pathogenic factors. First of all, the fungus can penetrate into plants and tubers through mechanical damage: punctures, incisions, fractures, eating tubers by cabbage borer, wireworm, and nematode. Therefore, mechanical damage to the tubers should be avoided as much as possible when planting, processing bushes, and harvesting.

Further, fusarium wilt can be a consequence of the lack of proper care for the plantation: if the potatoes are not weeded, loosened, excessively flooded with water in conditions of elevated temperatures, then favorable conditions for the development of the fungus are created.

The source of potato infection can be the remains of soil or other plants, organic fertilizers, infected planting material. The lack of preventive treatments with fungicides also plays a significant role in this case.

Symptoms of fusarium wilt of potatoes

The disease does not appear immediately, so it is difficult to diagnose it quickly. Visually, the beginning of the appearance of symptoms is manifested in the yellowing and browning of the upper leaves, which gradually lose their tone, begin to wither and curl into a tube.

The penetration of fungal spores into the stems provokes their growth and clogging of vessels, which blocks the plant's metabolism. If you break the stem, you can see yellowed and browned vessels. From above, the stems are covered with a light coating of white color.

As for the tubers, they are covered with brown spots, under which the flesh of the tuber begins to slowly rot. In the end, the pulp under the skin becomes rotten, rotten and the tuber or its part can easily crumble under mechanical influence. At the same time, the diseased tuber infects the rest of the potatoes that are stored together with it. Therefore, during harvest, infected vegetables should be thrown away immediately.

Fusarium disease biology

After entering the plant, fungal spores develop in the conducting system of the potato. In addition to clogging the vessels, spores can cause intoxication of the potato bush. The most favorable moment for the onset of fusarium is the flowering period of potatoes, when their immune system is maximally weakened. Gradually, fusarium leads to rotting of plants and tubers.

Fusarium infection during storage

Potatoes can also become infected during storage. This is possible only if:

• infected soil or organic residues from the previous harvest remained in the storage place;
• infected tubers were not selected during the laying of potatoes for storage;
• if potatoes were mechanically damaged during harvesting;
• if measures to protect potatoes from pests, as well as the temperature and watering regime, were not observed during growth, then during the laying period the potatoes may already be infected.

In order to prevent fusarium infection, the storage place should be cleaned as much as possible and treated with fungicide solutions. You should also minimize picking potatoes so that diseased potatoes do not infect healthy tubers.

Control measures and protection against fusarium wilt

In general, measures to combat Fusarium wilt should be divided into two groups: agrotechnical and biological.

Agrotechnical measures include:

• timely weeding of beds;
• moderate watering;
• preventive treatment of tubers before planting, as well as treatment of bushes during the growing season;
• removal of infected bushes from beds and their destruction (burning);
  compliance with crop rotation rules.

The chemical effect is treatment with biological and chemical reagents that affect the foci of the disease and destroy fusariosis pathogens from the inside.

Biological fungicides

Biological fungicides are preparations for combating fungal and bacterial diseases, which contain useful microorganisms that destroy disease-causing cells. Fungicides of this type are considered the safest, so they are used by supporters of organic farming. In particular, biological fungicides include Sporomax™ B (Bacillus subtilis bacteria) and Sporomax™ T (Trichoderma harzianum fungus spores), the dosage is 10 g/10 l of water.

The simultaneous use of both fungicides enhances their effect and reliably prevents the development of Fusarium wilt.

Sporomax™ T is also used to disinfect the soil before planting potatoes and to treat places where tubers are stored (basements, cellars, sheds, etc.) by spraying the room with a knapsack sprayer.

To reduce the degree of infection of potato plants, it is necessary to treat the soil with these preparations before planting the tubers and for a better effect of the drugs on the leaf, it is recommended to add the adjuvant Izomax™ 2ml/10l to the tank solution, which will allow to evenly cover the thick tops of the potatoes with the active substance and accelerate the penetration of the drugs into the plant.