What is a potato nematode and how to deal with it

The potato nematode appeared on the territory of the USSR in 1949. The first outbreaks of infection were detected in the Kaliningrad region. Microscopic worms are dangerous because in the first years of soil infection they do not affect the productivity of potatoes and their taste, but as they multiply and spread on the site, they destroy more than 60% of the crop.

Consider the description of the pest and the methods of treating the plants affected by it.

Description of the pest

The potato nematode is a quarantine pest belonging to the cyst-forming nematodes of the Heteroderis family (various nematodes). In addition to potatoes, it affects other plants of the Solanaceae family (eggplants, tomatoes, physalis). Depending on the climate, it gives 1-2 generations per year. Reproduction is bisexual.

Roundworms are characterized by sharp sexual dimorphism (two different forms of individuals within the same species). The female is 380–1070 µm long and 275–965 µm wide. The body color is pearly white, the shape is hemispherical or oval. During development, the color changes from white to yellow. During the transition to the cyst stage, the female becomes golden.

The length of the male is 890–1270 µm, the width is 31–46 µm. The body is vermiform, narrowed at the ends.

The larva is 366–570 µm long and 18–26 µm wide. The body is narrowed on both sides.

The vital activity of adults takes place inside the potato rhizome at a temperature of + 15 ... + 20 ° C. Males do not feed. Their main task is to find a female and fertilize her within 10 days. After that, the male dies.

One female reproduces 200-1000 eggs, which overwinter in a cyst (a dead female with eggs). The cyst easily leaves the roots and remains in the soil until spring. At an air temperature of + 12 ° C, larvae appear and infect potatoes.

One generation develops over 38–48 days. Wet weather with prolonged rains promotes intensive reproduction and development of the potato nematode.

Nematode species

There are several types of roundworms: golden, stem, pale, gall, leaf. Potatoes are prone to infection with golden nematodes.

Golden

The pest penetrates the rhizome and feeds on plant juices. This makes it difficult for nutrients to reach the stems, greens and young tubers. The potato bush begins to dry from the lower leaves. Tubers are formed small or not at all. The rhizome is strongly branched. The people call this phenomenon bearded.

Males resemble tiny worms. The body of females is spherical; 384 days after fertilization, it is filled with eggs. By autumn it gets dark, becomes golden brownish.

Pictured is a golden potato nematode.

Stem

This worm is only 1.7 mm in size and infects potato stems and tubers. Small dark spots are clearly visible on the infected tuber. Under the skin, you can see areas of loose light flesh. The surface is covered with cracks, dry rotting rot forms under it.

A stem nematode develops when there is excessive moisture. The worm parasitizes in damp cellars, crawling from tuber to tuber, infecting all planting material.

Pale

The pallid nematode has a developmental cycle similar to that of the golden nematode and differs only in color. In this case, the white body of the female acquires a brown tint.

The first signs of defeat are painful look of bushes. On such plants, no more than 3 stems are formed, which turn yellow prematurely. The infection spreads upward, starting from the lower leaves, and gradually covers the entire bush.

A small number of small potatoes weighing no more than 40 g are formed on a diseased bush.

Gallic

Gall nematode attacks potato roots and tubers. It parasitizes pumpkin crops: squash, squash, melons, pumpkins. Bumps, sometimes growths, up to 3 cm in diameter appear on the tubers. The infected plant lacks nutrients and moisture.

Sheet

The smallest nematode species. The length of the worm does not exceed 1 mm. The body is colorless. The pest moves inside the infected plant, provoking the attachment of viral infections.

Leaf nematodes parasitize not only potatoes, but also chrysanthemums and tomatoes.

Yellowish spots appear on the leaves. Soon the greens dry up and fall off. The worm spreads through wounds on the plant.

Symptoms of defeat

The danger of the potato nematode lies in the latent course of the disease. The first signs appear when the number of pests reaches a critical point. On the potato plantation "bald spots" appear: yellow and dry bushes are visible among the green mass. Tubers become smaller.

Small round cysts resembling grains of sand are visible under a magnifying glass. Often they are invisible, but at the slightest suspicion, it is better to hand over the wilted bush to the laboratory.

How to deal with a pest

A potato nematode is defined by the following expression: "It does not burn in fire, does not drown in water." To fight with pest it is very difficult, for this they carry out a whole range of measures, including agrotechnical techniques and treatment with chemicals. At the same time, no means guarantee absolute effectiveness. Farmers of the EU countries have extensive experience in fighting nematode, given that it appeared there earlier than in Russia.

Reference. If your site is in the quarantine zone, if you follow a number of rules, you will be able to grow excellent potatoes. It is important to remember: a product from such a zone is used in cooking, but is not sold in other regions.

The final victory over the potato nematode will take more than one decade of continuous work, but the pest population can be reduced in 1-2 years.

If there are no more than 3-5 cysts per 100 cm3 of soil, there will be no harm to the potatoes. A significant decrease in yield is observed when 10-16 cysts are found per 100 cm3 of land.

Agrotechnical methods

To combat the pest, simple but effective agrotechnical and preventive methods are used:

1. Crop rotation. Potatoes are not planted in the same area for several years in a row. Even if a crop is planted in one place no more than once every 3-4 years, a serious increase in the nematode population will occur no earlier than in 40-45 years.
2. Pest-resistant varieties are planted only for 3 years in a row, the next year they choose ordinary planting material. There is another option - to grow only crops with a high degree of protection, but change varieties every 4 years.
3. In autumn, potato tops and weeds from the infected area are harvested and burned, taking precautions. The working tool is disinfected with a 4% formalin solution.
4. In autumn and spring, the soil is fertilized with urea. Nitrogen is harmful to potato nematodes. With a slight spread of the pest on the site, they dig a hole, dump the tops and weeds into it, cover everything with urea (5-6 kg / 1 m3 of green mass), and sprinkle it on top with soil from a "clean" area.
5. Healthy material is chosen for planting. The tubers are washed and treated with a solution of potassium permanganate (0.5 g / 10 l).
6. When disembarking, add 1 tbsp to the holes. l. bird droppings. A solution is prepared from fresh droppings in a ratio of 1:10 and the area is watered.
7. Rye, beans, peas, marigolds, clover and mustard are planted next to the beds. The roots of these plants secrete substances that are harmful to the nematode.If rye is sown in the field in the second decade, up to 90% of the larvae are destroyed, and rotted straw serves fertilizer in the spring. Nodules containing nitrogen are formed on the roots of legumes. The seeds are added directly to the holes or planted between the rows of potatoes.
8. Ringed (earth) worms are natural enemies of the nematode. Increasing soil fertility creates favorable conditions for their reproduction.

Chemical method

When the potato nematode is massively spread, chemicals are used. Processing is carried out 6 weeks before planting the culture, following the manufacturer's recommendations.

For the destruction of nematodes, powerful fungicides are used: Chloropicrin, bromomethane (methyl bromide), Nemagon. These funds are released in the form of poisonous gases. They are used to process soil and seed material. Penetrating into the respiratory system of worms, toxins cause their death. The work is carried out in the means of protection of the skin and respiratory tract.

Preparations based on organophosphate nematicides (Lindane, Karbofos, Phosphamide) are used to eliminate stem and leaf nematodes. The prepared solutions irrigate the planting material.

Important! Given the high toxicity of drugs against potato nematode, landing tubers in the treated areas are produced in 20-50 days.

Biopreparations "Basamil", "Phytohit", "Nematofagin BT", "Pecilomycin" do not have a toxic effect on tubers and are effective against the pest.

Folk ways

One of the most effective folk methods of getting rid of nematodes is to pour boiling water over the soil. No herbal infusions and decoctions will cope with the pest.

The infected area is evenly watered with boiling water to a depth of 20 cm. A plastic wrap is pulled on top. This will cool the earth more slowly. The method destroys worms that settle only in the upper soil layer. The nematoda, parasitizing in the deep layers, moves to another part of the garden.

Harm to humans

The pest poses no danger to humans. However, it is undesirable to eat tubers affected by a nematode: they lose their taste and acquire an unattractive presentation.

Potato varieties resistant to nematode

The table shows the varieties with immunity to nematodes. The root system of plants resists parasites, killing about 80% of the worms.

Conclusion

Potato nematode is an insidious pest that can leave the gardener without a crop if control measures are not taken in time. It is difficult to destroy it, but compliance with the rules of agricultural technology and preventive measures (crop rotation, harvesting tops and weeds, disinfection of seed material, selection of varieties resistant to pests, nitrogen fertilization), treatment of potatoes with fungicides based on organophosphate nematicides and toxic gases, watering the beds with boiling water greatly reduce population of worms.