Despite the fact that the potato is an unpretentious plant, it is one of the most affected by diseases and pests of crops. All summer residents know about the Colorado potato beetle, which can be seen with the naked eye. However, large losses in potato yield can be caused by a microscopic pest - potato nematode. This is a round worm, the size of which does not exceed 1 mm.
All potato nematodes are highly fertile and subsist on the host plant. In Russia, there are several types of this pest.
These two species are potato cyst nematodes and cause disease globoderosis... Malicious pests, they are objects of internal and external quarantine in the Russian Federation.
If potatoes are severely damaged, the farmer can lose up to 80% of the crop.
The pest lives in the ground, spreads through the soil, containers and tools, tubers with earth residues, melt water, etc. It is stored in the soil up to 10 years.
The golden potato nematode is found all over the world, including in Russia, especially in its central part and Siberia. Pale nematode is common in Europe, Latin America, Canada, cases of appearance in Russia are not registered.
The life cycle of both types of parasite is the same and continues about 40-60 days... The pest hibernates in the form of larvae and eggs in strong cysts.
In the spring, when young potatoes emerge, the eggs develop into larvae and penetrate the roots of the plant. The maximum range of their movement in the soil is 1 meter. In the roots, they lose mobility and develop until they turn into males and females. The optimum temperature for life is 15-20 degrees.
Males enter the soil completely, and females gradually grow, thicken and tear the roots, remaining partially inside the plant. After fertilization, the males die, and the females begin to lay eggs inside their own body. Fertility of one individual - from 200 to 1000.
When the eggs are ripe, the female's body dies off, its outer shell becomes hard and turns brown. This is how a cyst appears - a dead female with eggs inside. When harvesting potatoes, the cysts crumble, fall into the soil and winter there.
Golden nematode is called because during its life cycle her female changes color: first it is white, then cream and finally golden yellow. In females of the pale nematode, the white-cream color remains dominant.
The pest affects not only potato stems, but also tubers with leaves.
The female can lay eggs at a temperature from 5 to 37 degrees... The life cycle takes 20-45 days... Pests hibernate in the egg stage, while tolerating soil freezing well.
Early varieties are especially harmful. Infection occurs more often from the mother tuber than through the soil. From the ground, the nematode enters the tuber while it is forming. The pest infestation is especially strong in rainy years.
The pest parasitizes various plants, including potatoes, which causes tuberosity... Growths (galls) appear on the roots of an infected plant, as a result of which the internal vascular vessels become clogged and the plant begins to experience a lack of nutrients. In cold winters, it dies in the soil.
There is a danger that in the coming years other species of root-knot nematode - Colombian (Meloidogyne chitwoodi) and nematode Meloidogyne fallax - may appear in Russia. These pests are already found in European countries.
The defeat always begins as focal.
7 weeks after planting, pest cysts can be seen on the roots, first white, then bright yellow and eventually red-brown.
Tubers always small and few... Symptoms are especially pronounced if potatoes grow on poor, poorly fertilized soils.
Usually there are no external manifestations of the pest. In case of severe defeat leaves turn pale, become wavy at the edges... The internodes are shortened, the stems become thicker and bushy.
On tubers under the skin appear small white spots with a hole in the center... The pulp gradually becomes soft in the affected area. During storage, dark leaden spots form on the tubers. Over time, they grow and crack, from which the tuber dries quickly.
In a humid environment, during storage, the parasite is able to spread from diseased tubers to healthy ones.
The main method of pest control is use of nematode-resistant varieties and avoidance of monoculture.
Since the parasite lives in the soil, the annual planting of potatoes in one place contributes to the rapid spread of the pest. To prevent this from happening, you should alternate potatoes with the cultivation of other crops, that is, observe 4-5 year crop rotation.
The best predecessors will be plants that are not affected by this pest:
If summer residents do not have the opportunity to use long-term crop rotations and constantly change the place for planting potatoes, they can be advised on the method of one-year "covered" steam.
The essence of the method: in the fall, after harvesting and thoroughly cleaning the field from plant residues, they bring manure (160-240 t / ha), dug up and snatch with a thick layer of mulch. For example, you can use chopped straw, hay, or grass cuttings. With a layer of mulch, the field is left for the winter.
At the beginning of summer, all sprouted potatoes that were missed during the autumn harvest are removed from the site. The shelter is not removed. During dry season water the field 1-2 times... After the next wintering, the remnants of the mulch layer are removed, a nematode-resistant potato variety is planted in the field and grown for at least two years in a row.
The effectiveness of the method: under favorable weather conditions (warm winter, a lot of precipitation in summer), the destruction of the pest can reach 98%. Nematode larvae will die from natural enemies: bacteria, ticks, predatory fungi.
It is impossible to constantly plant only nematode-resistant potato varieties. This can lead to the pest becoming more hardy. A common variety is planted every 3-4 years.
Strong chemical preparations can be ineffective, since the cysts in the soil are protected by a hard shell, and after the larvae are introduced into the plant, the use of pesticides can harm the future harvest.
Some chemical treatments:
Popular ways to deal with a pest include the following tricks:
If there is a suspicion that the potato bush is infected, it is necessary to carefully dig it out together with a lump of earth, inspect the roots. If they have small golden balls on them, it could be parasite cysts.
Such plants need remove from the site and burn... After working with an infected plant, you need to rinse well, and it is better to disinfect containers, tools and shoes that have come into contact with the ground.
In general, correct observance of crop rotation, careful care of potatoes, timely application of fertilizers to the soil help prevent the spread of the parasite on the site. After all, the best way to combat any plant disease is prevention.
The quarantine phytosanitary regime for potato nematode was canceled in nine personal subsidiary farms of the Porkhovsky district of the Pskov region after three years of monitoring. Why it is necessary to comply with the time frame and what crop rotations to use to combat nematode disease of the potato, read right now
The Rosselkhoznadzor Administration for St. Petersburg, the Leningrad and Pskov regions carried out quarantine phytosanitary examinations of nine private subsidiary farms in the city of Porkhov, Pskov region.
In 2008, on the territory of these farms, with a total area of 1.28 hectares, a quarantine phytosanitary zone was established for a quarantine object - golden potato nematode (Clobodera rostochiensis (Woll).
As a result of the investigations carried out in these territories, no cysts of the golden potato nematode were detected for 3 years. By order of the Rosselkhoznadzor Office, the specified quarantine phytosanitary zones were abolished, the quarantine phytosanitary regime was canceled.
Golden potato nematode is subject to external and internal quarantine of the Russian Federation. Among the diseases and pests affecting potatoes, nematode diseases occupy one of the first places.
The harmfulness of the nematode lies in the fact that with a strong defeat of the potato, growth slows down, the tops turn yellow, the stems lengthen, the lower leaves die off, the potato becomes small, the yield decreases sharply, the tubers are sometimes completely absent. In addition to potatoes, it affects tomatoes, eggplants, and other plants of the nightshade family. Heavily infested bushes die long before harvesting, not forming at all or forming very small tubers.
The quarantine organism penetrates the roots of potato plants and parasitizes inside, feeding on plant tissue. In this case, the digestive enzymes secreted by the nematode have a toxic effect on the host plant. Cysts can persist in the soil for more than 10 years, without manifesting themselves in any way, but as soon as the roots of plants of the Solanaceae family (including potatoes and even weeds) are nearby, the cysts wake up, larvae emerge from the eggs and attack the roots, penetrating inside. On average, crop losses are 30% -50%, but can reach 80-90%.
The wide distribution of the nematode is facilitated by its high fertility, the ability to settle in the soil, to be carried with tools, with seed material.
Among the measures to combat SCI: the use of non-affected crops, nematode-resistant varieties of potatoes in crop rotation, fertilization, destruction of weeds, especially from the Solanaceae family. In a crop rotation system, potatoes should be returned to their original place no earlier than after 3-4 years. From the point of view of nematode control in the private sector, the best crops are cruciferous plants (radish, radish, turnip, mustard).
Measures to combat quarantine objects should be comprehensive, and include not only agrotechnical, but also organizational and preventive.
In order to prevent the import and distribution of quarantine items, individuals and legal entities, individual entrepreneurs engaged in the production, import, use, storage, processing and sale of regulated products must:
- systematically conduct a quarantine phytosanitary survey of available land plots, storage sites, use of regulated products
- upon detection of quarantine objects or suspicions, immediately report to the Rosselkhoznadzor services.
The procedure for immediate notification was approved by order of the Ministry of Agriculture of the Russian Federation dated 09.01.2017 No. 1.
(Source: press service of the Rosselkhoznadzor Office for St. Petersburg, Leningrad and Pskov regions).
There are three varieties of nematodes dangerous for cultivated plants: golden potato, stem and gall. Each of them has its own characteristic features.
Golden potato nematode is a roundworm that infects only vegetables from the Solanaceae family. It causes particular harm to potatoes and tomatoes, parasitizing the root system and oppressing plants. The pest spreads most intensively in areas where potatoes are grown for several seasons in a row, without observing the required time interval of crop rotation lasting 4–5 years.
A tiny worm no more than 2 mm long is fixed on the roots with the help of a special device and feeds on the cellular contents. Particularly dangerous are females, which are somewhat larger than males and look like white grains of sand, tightly stuck to the root system of the plant. Over time, they harden and with the onset of autumn acquire a golden hue, turning into cysts. Each cyst is filled with several hundred eggs or larvae, which can survive in this form for about ten years, without dying during drought or severe waterlogging, from sudden temperature changes and even when exposed to aggressive pesticides.
Stem nematode primarily affects the aerial part, gradually descending to the tubers. The most susceptible to this pest are young plantings, whose stems become abnormally thickened and branched, the leaves become smaller and lose their color intensity, and the internodes become shorter.
Tubers affected by the nematode stem variety are very poorly stored, while simultaneously infecting neighboring healthy fruits. Sometimes the volumes of the lesion are so large that by the spring all the reserves become completely unusable for human consumption.
Gall nematode dangerous not only for nightshades, but also for other families, for example, for pumpkin. Tubers and roots attacked by this worm become lumpy, and the plant itself begins to noticeably lag behind in development, since nutrition in the aerial part does not come well due to the compression of the vessels by the formed galls. The secondary harm caused by the root knot nematode is the transfer of various viral diseases to the affected bush. On a massive scale, the infection of a site with this pest does not manifest itself immediately, but only after 5 or even 7 years.
Signs of infection are detected when the worms have already stuck to the roots or tubers of the plant. Usually this is the 40-50th day from the moment of landing.
The following symptoms indicate the presence of a golden nematode on the site:
A pale cyst nematode manifests itself with similar symptoms. Plants affected by worms are located on the site in a chaotic manner.
It is rarely possible to understand that a stem nematode has started in potato plantings during the growing season. In some cases, the plants become too curly. Another symptom is the thickening of their stems.
The most obvious signs of stem nematode infestation on tubers are:
When infected with a nematode, the yield of potatoes steadily decreases. In advanced cases, summer residents lose up to 80% of tubers. The soil in which the parasitic worms live is not suitable for growing nightshade crops. It will be possible to return them to their original place without the risk of infection only after 10 years. The pest is also dangerous because it weakens the plants, and pathogenic microorganisms easily penetrate through the damage that it leaves on them. Rot and fungal diseases are faithful companions of parasites.
Golden potato nematode is a roundworm that parasitizes potato roots during the growing season. It hibernates in the soil in the stage of eggs and larvae, enclosed in the shell of an old female (cyst).
In the spring, with the onset of warmth, with sufficient humidity, and also under the influence of substances secreted by the roots of potatoes, up to 200 larvae emerge from the cysts, which attach to the roots (except for potatoes, other plants of the Solanaceae family are also affected) and feed on their juice. Soon they acquire a spherical shape and golden color - hence the name. Their size is no more than a poppy seed. By the time the potatoes are harvested, ripe cysts are easily shaken off the roots, filling the arable layer.
With a weak population, you can detect a nematode in your own field only by digging a bush during flowering and examining its roots under a magnifying glass. With an average - you can already observe bald spots from oppressed plants lagging behind in growth with yellowed lower leaves. The number of tubers under the bushes decreases sharply, they become small (15-45 g). With a very strong colonization, tuberization does not occur at all; instead, only a mass of small fibrous roots is formed.
An important point
Cysts of golden potato nematode with larvae can persist in the soil capable of infection for up to 8-9 years even in the absence of a host plant (potato).
Typically, cysts are carried with soil, including those left on the tubers, brought to your site by wind, rain, tools (plow, hiller, shovel) or with the feet of the owner of the site walking through an infected neighbor.
The main spread of the parasite is infected planting material, which was grown in fields affected by helminths. This is especially true for tubers with pieces of earth adhering to them, carrying worm cysts. The container in which the crop is transported is also a source of infection.
There are three types of nematodes, due to which the disease occurs:
In addition to potato tubers, it infects tomatoes and parasitizes on weeds of nightshade crops. Golden potato nematode is a very small worm that feeds on the juice contained in tubers and causes bacterial brown rot. The massive occurrence of these individuals is considered to be a very dangerous quarantine parasite.
You can find out if the soil has signs of a golden nematode by digging up a potato bush after it blooms. If you remove the soil from the formed young tubers and take a good look, you will notice the smallest round blotches on the roots. These are mature female individuals of the worm with dimensions of 0.61 by 0.55 mm, having a pearl hue, over time, covered with a brown shell.
Resting cysts can survive fairly severe frosts, floods, dry periods and radiation effects. While at rest, they remain in the ground for a long time and show their viability even after 10 years. This potato disease is capable of spreading rapidly in moist and loose soil. The danger of the worm is that at the initial stage of infection, it is not possible to detect whether the soil is infected.
Golden potato nematode produces two generations of eggs per year (up to 1200 eggs).
After winter, part of the young nematodes emerge from the cysts, and, having made their way into the potato tubers, all stages of growth pass through there. In the process of life, they gradually suck out the juice from them, which causes deformation and slowing down of the growth of the stems and leaves of the plant.
Rapid contamination of the soil by the golden potato nematode occurs due to the phased release of the larvae from the cysts. This period can last 3-6 years.
This species attacks the stems, tubers and leaves of the plant, especially of early varieties. The appearance of potato bushes visually changes. Increased bushiness is noted, the stem becomes thinner than usual, internodes are shortened. The leaves take on a pale color, shrink, their edges become wavy.
The potato stem nematode itself infects tubers in the soil during active growth. During this period, the worm makes its way into the fruit through their stolons.
The extremely low mode of vigorous activity of the parasite is -5C. The female lays eggs at temperatures from + 5 to + 17C. The life span of parasites is 25-45 days.
Sizes of adults of potato stem nematode:
The harmful threshold of such a parasitic organism can be from 20 to 50 larvae per 1 kg of soil.
Potato stem nematode harms the crop during storage. In this case, gray spots are formed on the tubers, which then darken, break, revealing a brown mass instead of a dense white fruit, which is called "dry rot".
Rainy seasons are most favorable for the life of the stem worm. Click beetle damage to tubers also contributes to infestation.
Potato nematodes do not pose a danger to humans, as they can only damage plants.
It is a microscopic worm with a size of 1-1.5 mm. This parasite causes tuberosity on the tubers. The nematoda makes its way into the roots of potatoes and nests in their structure. They become the habitat of the worm. The toxic substances released by the parasite lead to the formation of various growths and protuberances (galls) on the roots, inside which the larvae develop.
This dangerous type of worm makes it difficult to supply water and food, as it affects the root system, on which plant life depends entirely. Bushes that have begun to grow first slow down in growth, and then die. The harmful effects of the potato nematode are especially dangerous in dry and warm weather. Their mass accumulation can not only damage bushes and tubers, they can serve as carriers of viruses and other diseases.
Females of stem nematodes are quite fertile. Up to several hundred galls can be found on the roots of one bush.
The nematode brings the greatest harm to potatoes in the fields and personal plots, where this vegetable crop is constantly grown. This situation contributes to the accumulation of pathogens and parasite cysts in the infected areas.
Sources of infection can be the affected soil, compost, humus, the tubers themselves, as well as the tools used by people.
Crop rotation is not only protection from the worm, but also a preventive measure that allows you to protect the site from it in the future. Re-planting in one place is allowed after 3-4 years, better later.
It should be borne in mind that infection with a worm of one of the considered species is the reason for quarantine in a particular area. If a nematode is found, the phytocontrol authorities should be reported. The sale of such products to other regions is prohibited. However, infected potatoes are allowed to be eaten, provided that they are not extensively eaten by rot.