Fusarium on crops of wheat and barley. Fusarium: signs of the disease, methods of control and prevention Fusarium spread rate

Plant diseases, as well as human diseases, have different modes of transmission.

It is quite possible to protect oneself from some of them, for example, by avoiding contact with an infected object or by moving away from the territory of infection. But there is a special way of transmission, which is almost impossible to defend against ...

Many of us have had chickenpox as children. Remember, not the most pleasant disease that can spread throughout the district with the speed of the wind - hence the name. It is almost impossible to avoid infection to an unprotected organism. Surprisingly, a similar disease exists in the plant world. Fusarium - this terrible infection scatters across the fields with every breath of wind, carrying the infection from ear to ear, from cob to cob and leaving behind a trail of death and defeat.

Fusarium head blight has been known in our country since the Russo-Turkish War, when an outbreak of a then unknown disease led to the death of the pets of the cavalry regiment, which was an indirect reason for the loss. In modern Russia, this infection was seriously discussed only at the beginning of the 21st century. The intensity of the spread and the damage done to agriculture turned out to be so great that even farmers, who had previously ignored plant protection products, willy-nilly turned towards chemicals. Epidemics of the disease are observed in most regions where wheat and rye are grown, especially in years when warm and humid weather conditions occur during the heading period of the crop. In Russia, Fusarium epiphytotics occur frequently (at least once in 2-3 years of vegetation) mainly in the North Caucasus, the Far East, in the northwestern and central parts of the country and in the Urals. Yield losses during the development of infection can reach 20-50%. Moreover, the growth of fungi in affected grains leads to the accumulation of toxic metabolites (mycotoxins) that are hazardous to human and animal health. Absolutely all cereal crops are affected.

What is fusarium? The causative agent of the disease is a representative of the genus Fusarium, a common and dangerous fungus that can infect a plant at any age. The fungus penetrates the plant through the soil and wounds, causing rotting of the roots and root collar. In the affected areas, the tissues turn brown, the stem becomes thinner, the leaves turn yellow, and soon the plant dies. Fusarium of cereal crops, which occupies one of the leading places among cereal diseases in terms of harmfulness, has been studied quite well, since it is widespread throughout the country. However, there are not many effective ways to deal with it. The danger of this infection is due to the many ways of transmission. The main sources of Fusarium are seeds, soil, crop residues of wheat, barley, corn, peas and weeds. Fungi are incredibly weather-resistant: they can overwinter on infected plant debris and seeds.

Outbreaks of the disease periodically appear in different regions of Russia: Kursk, Orel, Belgorod, Voronezh regions, Stavropol, Krasnodar Territory, Chechnya, Dagestan, Ossetia. And this is not a complete list.

In 2014, in the Stavropol Territory, a certain increase in the disease of winter grain crops with ear fusarium was noted, especially where the introduction of various technologies for minimal soil cultivation, violation of the crop rotation system and its oversaturation with cereal crops led to significant changes in the development and spread of the harmfulness of pathogenic organisms. The current year in the region was distinguished by an abundance of precipitation in a relatively warm climate, which contributed to the spread of fusariosis of the ear. Weather conditions comfortable for the infection during the flowering period (filling grain of winter spiked crops) favored the infection of plants, primarily in places where crops were previously affected by "snow mold" and root rot of Fusarium etiology. According to the branch of the Federal State Budgetary Institution "Rosselkhozcenter" in the Stavropol Territory, as of June 2014, 315 thousand hectares of winter crops or 18% of crops in 21 districts were affected in the region. The largest areas are affected in the 3rd zone - 151 thousand hectares (32% of crops), in Grachevsky - 40 thousand hectares, Trunovsky - 27 thousand hectares, Izobilnensky - 23 thousand hectares and in the Ipatovsky district - 123 thousand hectares. This is higher than the long-term average, but the spread of the disease in the fields in the region as a whole was low - from 1 to 5%. In order to avoid the spread of infection, regular monitoring of crops was carried out in the region for infection with ear diseases and, first of all, Fusarium in the phase of grain ripening. Measures have been taken for timely cleaning and separate storage of parties infected with Fusarium, if any. To date, 7.9 million tons of grain have already been harvested in the region. Checking the quality of grain showed a high percentage of food - 81%.

The situation in the Krasnodar Territory is not much different. In the current year, an early manifestation of fusariosis of the ear on winter crops was noted. The phytosanitary condition of winter wheat and barley crops was aggravated by heavy rainfall. The spread and development of the disease continues, the harmfulness increases, especially in the foothill areas of the region. According to the branch of the Federal State Budgetary Institution Rosselkhoztsentr in the Krasnodar Territory, the prevalence of infection on winter wheat was 2.5%, on winter barley - up to 9%, which exceeds the figures for previous years.

An example of the spread of Fusarium in two large regions of our country clearly demonstrates the seriousness and complexity of the situation. The mistake of most agronomists is in untimely response and the wrong choice of infection control methods. Ignorance, distrust of new technologies, inability to live "in step with the times" - as a result, ruined fields and millions in losses. But you can fight Fusarium. The main thing is to approach this issue comprehensively.

"Schelkovo Agrokhim" offers a new innovative approach to fight Fusarium and other common infections. CVS is a system for effective management of plant vegetation throughout the entire growth period. The system includes a number of measures that allow you to control the condition of plants at all stages of its growth: from soil cultivation to harvest.

What is CVS? Let me draw a clear analogy. Imagine a young but responsible couple planning to have a baby. What are they doing? Both spouses undergo a medical examination, take drugs to improve health before pregnancy. Further, during gestation, a woman reviews her diet, trying to make it more balanced and healthy, while taking vitamins. And after the birth of a child, all forces are rushed to maintain the health of the baby, observing the optimal diet for him. And all this is for the proper growth and development of a new, just emerging life. The same thing happens with plants grown according to CVS - the system for responsible farmers. CVS allows you to gradually control the growth and development of a plant and bring it to full maturity. Use of effective fungicides such as Benefit and Polaris in combination with an agrochemical Biostim Start will create the basis for the future harvest. Benefit and Polaris provide fast and deep penetration into the grain due to the innovative micro-imulsion preparative form, reliably protecting against helminthosporium-fusarium root rot and enhancing growth processes. Presowing treatment of winter wheat seeds with the preparation Biostim Start guarantees a high percentage of field germination. Seeds germinate a few days earlier and give friendly seedlings. The secondary root system is intensively formed, its active zone and water-absorbing capacity are significantly increased. Winter crops tolerate winter better and resume vegetation earlier. The tillering coefficient and the number of productive stems are significantly increased, as well as the number of grains per spike and the average grain weight, which leads to an increase in yield and grain quality. Fungicides Benazol and ZIM 500 protect against root and root rot in the autumn and early spring periods of vegetation and reduce the amount of the pathogen on vectors - plant debris; a Triad and Title Duo provide a long period of protective action and prevent a wide range of diseases of the leaf apparatus and ear.

At the stage of crop growth, micro- and organo-mineral fertilizers are used. Biostim Universal, Biostim Grain and Intermag Profi Grain that help the plant develop its own immunity through a balanced diet and protection from stress. Combination of drugs of series Intermag and Biostim will provide a higher utilization rate of mineral fertilizers and guarantee a cost-effective return on the costs incurred in cultivation technologies.

Also, the complex of preventive measures should include work to accelerate the decomposition of plant residues in the fields and reduce infection in the soil, thorough preparation of seed material, mandatory phytoexamination of seeds to identify the pathogen. In addition, it is recommended to rotate crops with a break of at least one year in the rotation and choose varieties tolerant to the disease for planting. The integrated approach promoted in CVS will allow you not only to give life to a new crop, but also to take care of its healthy growth, full maturation and, as a result, a good harvest. Your profit is in your hands.

Mirzaalieva Nargiza

ZAO Schelkovo Agrokhim

A significant amount of precipitation, combined with moderate temperatures in May and early June, contributed to the significant development of wheat diseases, and ears in particular. It is known that the physiological role of the spike in the formation of the future harvest is inferior only to the flag leaf and, according to various sources, is 20-25%. Therefore, protecting the ear from diseases is crucial for obtaining a high and high-quality wheat grain yield.

Wheat ear diseases: a danger to the crop

Particular attention should be paid to the monitoring and control of Fusarium, a disease of the ear of wheat, which had an epiphytotic development in 2014, and therefore a significant reserve of infection, despite its insignificant manifestation last year. The species composition of causative agents of diseases of the ear of wheat largely depends on the phase of plant development, the genotype and agricultural technology of the variety, temperature and humidity, and therefore differs over the years.

Fusarium head of wheat

Fusarium ear blight disease of wheat manifests itself in the heading phase and develops before harvesting. The affected ear acquires a light color (discolors) at the base, from its central part or top. Only individual spikelets can also be affected - then they acquire a light yellow color and are clearly visible against the background of other green ones (photo 1). The causative agents of the disease are fungi of the genus Fusarium.

On affected glumes, mycelium and conidial sporulation of Fusarium spp. in the form of purple pillows.

The penetration of pathogens into the central spike stem blocks the supply of nutrients to all spikelets located above. This leads to a billow (or empty ear).

Infection of plants occurs mainly during flowering, when ascospores of pathogens ripen. Wheat anther is a good nutrient substrate for the growth of fungi of the genus Fusarium, in particular F. graminearum. Fungal hyphae colonize anther tissues, penetrate the embryo, and spread by the grain coat.

It is believed that the degree of development of the disease is 70% dependent on the variety and agricultural technology, and 30% on weather conditions. The temperature of 20 ... 25 ° C and high air humidity (75% or more) in the period from flowering to harvesting contributes to the intensive development of fusariosis of the ear.

Diagnosis of fusarium ear of wheat

In turn, the degree of damage to the grain depends on the type of pathogen and the time of its penetration into the tissue. In this regard, two types of damage to the ear of wheat by the disease are distinguished:

1. A pronounced (deep) fusarium grain, according to a surface (macroscopic) analysis, is distinguished by plush and pink color due to the presence of fungal mycelium. This form of damage occurs due to early infection of the ears in the field (in the flowering phase), mainly by the fungi F. culmorum, F. graminearum and F. avenaceum.
2. The hidden (surface) form of Fusarium grain occurs when it is damaged late, has a weak infectious load, or is damaged during harvesting and storage of the crop. Such grain does not differ from healthy, but is a source of infection during its storage and sowing.

When analyzing grain, it is necessary to distinguish between fusarium, discolored and pink-colored (non-fusarium) grains. The main features characterizing Fusarium grains are:

• grain whitish, chalky, with complete loss of luster; on individual grains spots of pink-raspberry or cream-pink color are observed;
• endosperm is fragile, with mealy consistency; for late defeat by fusarium - from powdery to partially vitreous;
• most grains are shriveled, flat, with pointed sides and a well-depressed groove; in case of late defeat by fusarium - the shape of the groove and the size of the grain are close to normal, sometimes swollen, with exfoliated shell;
• the embryo is not viable, it has a black color on the cut; on the embryo and in the groove there is a mycelium of the fungus.

Discolored and pink-colored grains differ from fusarium fullness, normal endosperm and vitreousness, a viable pale yellow (on the cut) embryo without mycelium of the fungus. Pink-colored grains have a normal luster and spots of pink-red hues (mainly at the germ) that are not bluish.

The defeat of the ear leads to infection of the grain, as a result of which the crop shortage reaches 45-73%, the sowing qualities of the seeds deteriorate: the germination energy and germination can decrease by 24%, the weight of 1000 seeds - by 39-72%. The barrenness of affected plants sometimes reaches 60%. Laboratory germination of seeds from an ear with obvious signs of Fusarium can be reduced by 96%. The density of gluten and the baking properties of flour deteriorate, the amount of protein decreases by 1.3-5.6% with the release of ammonia, dangerous toxic substances (fusariotoxins) accumulate in the grain. When using fusarium grain for food or feed purposes, it can be a cause of poisoning for people and animals.

The most common representatives of fusariotoxins that pollute agricultural products are T-2 toxin, deoxynivalenol (DON, vomitoxin) and zearalenone (F-2 toxin). DON is most often excreted, and T-2 toxin is considered the most dangerous.

In grain with clear visible signs of fusarium, the mycelium of fungi of the genus Fusarium penetrates into all tissues - into the shell, aleurone layer and endosperm. The main localization of the mycelium of Fusarium spp. in grain with latent infection - pericarp cells. There is a deformation and a violation of the density of its transverse cells. The thickness of the cells of the outer epidermis increases by 1.5-2.0 times compared with unaffected ones, and the cells of the walls of the aleurone layer become thinner by 2.0-2.5 times.

The main sources of wheat fusarium infection are affected plant residues and seeds.

Septoria ear of wheat

Wheat ear disease manifests itself on the leaves, stem and ear of wheat. Typical signs of septoria leaves are the appearance of first light, yellow, light brown, and sometimes mild spots with or without a dark border. Black small pycnidia are located in the center of the spot or on its entire surface. Affected leaves often dry up. The spots on the stem are vague, without a clear border.

On spike scales, septoria appears as dark brown spots, sometimes with a purple tint (photo 2). In places of damage, the tissue may lighten and pycnidia appear on it.

Diagnostic signs of wheat ear septoria depend on the resistance of the variety, weather and agrotechnical conditions.

The mass development of septoria is facilitated by a temperature of 20 ... 25 ° C, the presence of drip moisture or a relative humidity of 90-100%. Under such conditions, pycnospores can germinate within a few hours after emerging from pycnidia. Dry periods of vegetation significantly suppress the development of the disease.

The grain in the affected ear becomes plush or completely absent. The underdevelopment of the ear leads to yield losses of 20-30% or more. Technological indicators of grain quality are significantly deteriorating.

Septoria infection persists on plant debris and seeds of wheat, shoots of carrion, winter crops in the form of pycnidia and mycelium. Wild cereals can also be a source of infection.

Olive mold on wheat acolos

Wheat ear disease manifests itself in wet weather during the ripening period on stems, physiologically aging leaves, spike and grain in the form of an olive-black velvety coating - mycelium and conidial sporulation of the pathogen (photo 3). After compaction, the plaque takes the form of sods.

With frequent rains, the spikelets affected by Fusarium are also populated by the causative agent of olive mold.

When wheat is harvested late and in rainy conditions, olive mold spreads quickly, causing blackening of the entire ground mass of plants. The development of the disease is enhanced by the presence of “honeydew” on the spikelets due to the high number of cereal aphids or the development of the causative agent of the horns (the fungus Claviceps purpurea (Fr.) Tul.). Yield shortfall can reach 10% or more. The affected grain is plush, has a reduced germination.

The main source of wheat ear disease infection is the affected plant residues and seeds, where the fungus persists as mycelium and conidia.

Hard smut of an ear of wheat

The first signs of smut disease of the ear of wheat are clearly manifested, starting from the phase of milky ripeness of the grain. At this time, the affected spikelets are somewhat splayed, with a blue-green color. During crushing of the affected grain, a grayish liquid with an unpleasant odor is released. Both individual spikelets and the entire ear can be affected. Affected spikelets do not bloom.

In the phase of milky-wax and full ripeness of the grain, the difference in the color of healthy and affected ears disappears. But in the affected spikelet, instead of a caryopsis, a smut sac (sorus) is formed with a fragile caryopsis shell, filled with a black mass of teliospores of the pathogen (photo 4). Such bags are easily crushed, have a much lower weight than healthy seeds. Therefore, in the phase of full ripeness, the affected ears often do not lean towards the soil, but remain straight.

Infection of plants occurs during the germination of spored seeds, before the emergence of seedlings on the soil surface. This is facilitated by cold soil (5 ... 10 ° C) at a humidity of 40-60%. Infectious hyphae of germinated teliospores penetrate the wheat seedling. Subsequently, the fungus spreads in the pericarp of the seeds, coleoptile, growth cone. But by the phase of milky ripeness, there is no significant difference between healthy and affected plants.

The source of bunt infection is spored wheat seeds. Seed material is clogged during harvesting, threshing, transportation and drying of the crop.

Diagnosis of infection of an ear of wheat with bunt disease

Regular phytopathological examination of crops makes it possible to establish the dynamics of the infestation of various varieties in order to make further decisions on the use of fungicides and the placement of grain lots on the current. The degree of ear damage by fusarium, septoria and olive mold is determined on a 5-point scale (Table 1).

When examining crops, at least 100 plants are selected evenly in different places along the diagonal of the field. The spread (P,%) and development (R,%) of the disease is determined by the formulas:

P = (n / N) × 100,

R = (Σn × b / N × 4) × 100,

where: n is the number of diseased spikelets (pcs.); N - the total number of accounting ears (pcs.); Σn × b - the sum of the products of the number of ears and the corresponding damage score; 4 - the highest score on a 5-point scale.

It is also important to take into account the presence of mycotoxins, fusarium and soot grains in a batch of wheat grain, depending on its purpose (Table 2).

Protection and control measures for ear diseases in wheat

To protect the ear of wheat from the described diseases, a complex of agrotechnical and special measures is used to prevent plant infection and seed spores during the growing season, collection and storage. In particular, they include: cultivation of resistant varieties; properly organized seed production; the use of a complex of agricultural practices aimed at increasing the resistance of plants; mandatory disinfection of seed, agricultural machinery and equipment; selection of preparations-protectants on the basis of approbation of seed crops and phytopathological examination of seeds; fungicidal protection of plants during their growing season. The use of recommended fungicides (“List ...”, 2014) is carried out on the basis of the forecast data for the development of diseases, taking into account the economic threshold of their harmfulness (EPV) (Table 3).

Measures to limit the development of wheat ear diseases

Compliance with scientifically based crop rotation and agricultural technology of crops and varieties is an important phytosanitary factor that prevents or limits the development of diseases.

Crop rotation. Wheat (especially seed crops) is recommended to be sown after a busy fallow, peas, early ripe soybeans. The development of diseases is facilitated by the placement of wheat after grain ear predecessors and corn. The plant remains of these cultures are a good substrate for the accumulation and preservation of the infection. Wheat crops after corn are two to three times more affected by Fusarium than after peas and soybeans.

Growing resistant varieties. Cultivation of highly productive genetically close varieties of cereal crops over large areas enhances adaptability and mass distribution of pathogens in agrocenoses. Soft wheat cultivars are considered to show higher resistance to Fusarium than durum wheat. Varieties with a thickened straw, a dense cuticle and in which the glumes adhere tightly to the grain are also less affected. Varieties with an extended growing season or flowering phase are more susceptible to disease. As is known, the ear can be infected with ascospores carried from plant debris in the soil. Therefore, undersized varieties are more susceptible to infection than tall ones. The best option is to grow not one, but two or three resistant varieties at the same time. Even under favorable conditions for the development of Fusarium, resistant varieties are able to show tolerance to the disease (not reduce yields).

Phytopathological examination and seed dressing. Direct crop yield losses caused by seed diseases can exceed 20%. Therefore, seed dressing is an obligatory event in the technology of growing agricultural crops, which makes it possible to protect young seedlings from seed, soil, and, in some cases, from aerogenic infections.

Seeds are carefully sorted before sowing to remove the plush and light grains, which are often a source of Fusarium pathogens. A phytopathological examination of seed material is also mandatory to establish the species composition of pathogens, the nature of the infection (internal, external or mixed) and the degree of seed damage.

The method of seed germination in filter paper rolls makes it possible to determine its sowing qualities depending on the degree of disease development. Disinfected seeds (100 pcs.) with an interval of 1 cm are laid out on filter paper 115 × 10 cm in size, moistened to full moisture capacity with sterile water, and fixed with a narrow strip of moistened paper. After that, the paper is wound into a roll, placed in a glass vessel and placed in a thermostat at a temperature of 23 ... 25 ° C. Rolls in a thermostat are periodically moistened.

After 7-10 days they are deployed, the laboratory germination of seeds and the degree of development of the disease on the seedlings are determined on a 5-point scale: 0 - seedlings without signs of disease and mycelium of pathogens; 1 - seedlings are normal, fungal mycelium is formed on seeds and seedlings; 2 - slight darkening of the tissues of the seedlings in the form of strokes or small spots; 3 - deformation of the seedlings with continuous spots on them and decay of the tissues; 4 - decay and death of the seed during germination. The degree of seed damage and disease development is determined by the above formulas.

The efficiency of seed dressing depends on the correct choice of preparation based on the results of phytopathological examination of seeds (Table 4). Seeds with a proportion of Fusarium grains above 20% are not recommended to be sown. The presence of smut infection is determined by centrifugation followed by microscopic analysis of the sediment.

Soil treatment from diseases and pests of wheat. The development of diseases is facilitated by the use of the no-till system, surface tillage and shallow incorporation of plant residues. It is also advisable to exclude the stacking of straw next to wheat crops.

Compliance with optimal sowing dates, seeding rates and seeding depth. Sowing wheat at the beginning of the optimal time allows you to accelerate the maturation of plants and avoid severe damage to crops. To avoid smut of durum winter and spring wheat, seeds should not be allowed to fall into cold soil.

Deep seed placement delays the emergence of seedlings, which is manifested in the weakening of plants, increased development of root rot and hard smut. Excessive seeding rates lead to thickening and lodging of crops, and this, in turn, contributes to the development of fusarium.

Ensuring a balanced mineral diet is carried out on the basis of an annual agrochemical survey of the fields, taking into account the needs of plants for the planned harvest. The introduction of high doses of nitrogen fertilizers, not balanced by other elements, often leads to soil toxicosis, the accumulation of pathogenic fungi in it. The latter are able to enhance the development of root rot and ear fusarium.

The use of nitrogen fertilizers in high doses enhances the development of fusariosis of the ear by three to seven times. A lack of nitrogen can lead to lodging of wheat, in the presence of rain and high temperatures will contribute to the development of diseases. In general, the application of higher doses of fertilizers can prolong the synthesis processes in the grain until the phase of full ripeness. This leads to a sharp increase in the nutritional resources of pathogenic fungi, lengthens their stages of development on the host plant and the duration of the period of mycotoxin production.

The use of fungicides against diseases of the ear of wheat. Seed dressing (tebuconazole, carboxin, etc.) is used directly against hard smut. Regarding the control of other described diseases of the ear, they focus mainly on the most dangerous of them - fusarium. Protection against Fusarium head blight, as a rule, makes it possible to limit the development of Septoria and olive mold at the same time. Apply one of the recommended fungicides (Table 5) in the phase of the beginning of flowering (appearance of the first visible anthers), and, if necessary, again in the phase of milky ripeness of the grain. The choice of terms for processing crops is due to the fact that the highest development of the disease is manifested when plants are infected in the flowering phase, less - with milky-wax ripeness. Fungicides of triazole groups are quite effective in protecting wheat from phytopathogens of the genus Fusarium.

Harvesting. At the first signs of fusarium or olive mold, a pre-harvest inspection of crops is carried out in order to establish the degree of infestation of various varieties and the subsequent placement of grain lots on the current. Affected crops are harvested in a short time and stored in separate batches. Fungi of the genus Fusarium can develop on wet grain even at a temperature of 3 ... 8 ° C. Therefore, to prevent the accumulation of mycotoxins, it is urgently dried to a moisture content of 14%.

A. Dermenko, cand. Agricultural Sciences, Department of Phytopathology NUBiP Ukraine

As soon as it hatches, the tender and translucent root rushes to where it will spend its whole life - down into the fertile thickness of the soil layer ...

And there is the enemy. One of the worst phytotrophs is waiting for prey, invisible and inaudible. He spread the hyphae like trapping nets, scattered the poisoned bait of spores. Lurking here and there are well-protected capsules, ready at the slightest touch to throw out a destructive "landing". Fusarium, omnipresent and all-pervading, able to wait for years, never misses its chance. He is the culprit fusarium, a disease that mows down entire fields.

Fusarium - who is it? omnivorous family

[!] Saprophytes are fungi or bacteria that live off the remains of dead organisms. Symbionts are fungi or bacteria that live off living organisms.

List them all? Not only this article, but also a multi-volume book will not be enough. The top three included only those who particularly “distinguished themselves” in a field that was by no means noble. Simply put, the most harmful.

(F. graminearum), feeding on the tissues of the host plant, "in gratitude" saturates them with poisonous secretions. "Drunken bread" ... a harmless-looking name refers to a deadly syndrome - alimentary-toxic aleukia (ATA). In the forties of the last century, thousands of people fell victim to the fungus, mainly residents of the Urals and the Volga region.

Healthy (left) and fusarium-affected spike. Fusarium cereal under the microscope

(F. nivale). Micronectriella snow. No mushroom has ever caused as many tears as this one. Spring, the snow melts in the fields... Not at all: winter crops remain under a white blanket. More precisely, under the shroud. Because it's not snow at all. Farewell, hope for the harvest ...

(Fusarium solani) and its genetic counterpart Nectria haematococca. Contrary to the name, it is not limited to potatoes. In the sphere of his "interests" are all nightshades, legumes and pumpkin. And that's not all: on the "conscience" of the fungus outbreaks of tree cancer, reaching the scale of epiphytosis.

A plant affected by potato Fusarium (left) and a healthy specimen. Fusarium potato under a microscope

From fusarium suffers losses not only agriculture. The omnivorous family is able to ruin a forest nursery and a garden center, let the owners of vegetable greenhouses and flower greenhouses go around the world. Of course, if they are careless.

Like a true mafia, the Fusarium never goes into business alone. For example, Fusarium graminearum is always accompanied by "cousins" - F. avenaceum, F. culmorum, F. poae, F. sporotrichioides and others. Nektria hematococcus acquired a no less magnificent retinue: it is followed by Fusarium heterosporium, F. ubglutinans and F. verticilliodes, Fusarium oxysporum ... And again, the ubiquitous F. graminearum, which for the sake of this occasion took the form of corn gibberella (Gibberella zeae).

The attentive reader will ask: what does Nectria, Gibberella and Micronectriella have to do with it? Mushrooms of this genus have two life forms, sexual (teleomorph) and asexual (anamorph). Their physiology differs, however, in fact they are one and the same.

So: the asexual form is the Fusarium. And nectria, gibberella, micronectriella and others are its second, highest hypostasis.

Fusarium - signs

Summer day in the garden is full of life. You can directly hear how everything around is growing, blooming, gaining ripeness ... But the keen master's eye notices: the tops of one of the plants do not look very good. Yes, and others, next to him, became discouraged ... Water, urgently! But the leaves behave somehow strange: instead of cracking down, they droop and are completely hopeless.

A beginner usually makes a lot of unnecessary gestures: he waters again, already more generously; loosens the soil, shade, even fertilizes just in case. Finally, he decides to spray from insects: so what if they are not visible, they probably hid ... This is usually where it all ends. The plant is sent to the compost heap (again, an error, why, we will explain below).

An experienced grower will not waste a minute. Anyone who already has some experience with Fusarium will cut off the affected shoot and examine the cut. Preferably under a magnifying glass, even better if you have a microscope. However, the characteristic dark ring is visible to the naked eye. These are vessels clogged with fungal hyphae.

“Ah, you are… wilt!!” the agronomist swears. And send the plant to the laboratory. For the disease, whose name comes from the English wilt, that is, “wither”, is generated not only by the Fusarium.

Withering. In our country, this term is most often accompanied by the word "verticillium". Foreign phytopathologists, having found hyphae inside the vessels, make a general disappointing diagnosis: wilt. Synonym: tracheomycosis. For a single representative of the flora, this sounds like a sentence. For the treatment of wilt is not subject to. And it doesn’t matter if it is of Fusarium origin or Verticillium. The drooping shoots say: late.

Fusarium affects plants of any age. If these are seedlings or seedlings, then we are talking about the so-called black leg. There, it doesn’t come to wilting - a fresh-looking shoot falls overnight, with a characteristic constriction in the region of the root collar. But an older plant is still able to resist. Not for long, however - from several days to a month or two, depending on the size and species.

Since the Fusarium lives in the soil, the attack always starts from below. For some time, nothing is noticeable, because an adult has a lot of vessels, and their walls are quite strong. The fungus gradually moves up to the young tissues, supporting the forces with plant juices. The incubation period can take up to thirty days. Growing, hyphae seal the vessels completely. Moisture does not go up, photosynthesis products go down. Everything, the "circulatory system" no longer functions.

Sooner or later, under the pressure of the mycelium, the walls of the vessels burst, and the fruiting bodies come out into the air. But this is the final stage of Fusarium, when the plant is actually dead.

So, the signs of Fusarium wilt, as the infection develops:

• chlorosis and watery areas on the leaves;
• loss of turgor;
• dark ring, clearly marked on the cut;
• darkening, when viewed through the light, of the vascular network of the sheet;
• drying and dying off of the aerial part;
• the appearance, usually in the region of the root collar or in shaded areas, of whitish plaque, and more often reddish mold, that is, sporulation of the fungus.

The sequence described above is not always followed. Even a venerable phytopathologist, who has devoted half his life to studying Fusarium and fighting it, will not assert anything without laboratory tests.

However, the most important visual inspection will give: confidence that the simplest fungus was attacked. Which one is not so important. Because most modern fungicides have, let's say, a wide "field of fire". That is, they are universal or almost universal.

root rot

In fairness, first you would need to describe the "roots", and then the "tops". The appearance of Fusarium in the aerial part of the plant is preceded by a long and methodical work on the destruction of the root system. A fungus is an inhabitant of the soil, and in this environment it feels more confident than anywhere else. If the situation at the top does not suit him with something (for example, an abundance of sunlight or good ventilation), then he will remain underground. Good food in abundance.

Plant roots not only draw moisture from the soil, but also release their own substances. It is on them that the threads of the mycelium react. And they attack. Breaking resistance is not difficult. Yes and no, where from? After all, the root cap is probably the most delicate and unprotected organ of the plant. Having broken through, with the help of enzymes, a barrier only one cell thick, the Fusarium settles inside. It is arranged in a businesslike way, thoroughly growing into the walls. Eats, adds on everything ready. Along the way, it slowly but surely poisons the host, throwing mycotoxin poison into his body.

He does not appreciate "housing", he does not appreciate it at all. However, what is the point of the Fusarium to save the life of its carrier? The fungus assimilates the organic matter that is at the initial stage of decomposition much better.

A serious source of Fusarium are stored tubers, bulbs, root crops. A little less often - fruits and seeds. The names correspond to the nature of the lesion: dry rot of potatoes, red rot of bulbous, or clamp rot. For those who do not know, kagaty are industrial storage cellars, huge in area. That is, a place where, if overlooked, the fungus "unbelts" with might and main, nullifying the work of vegetable growers. The home underground, of course, does not reach the kagat. So what, the Fusarium will not disdain, will pay a visit there as well.

Risk group

The most famous victims of Fusarium are crops. In the middle lane, wheat, rye, barley, soybeans, peas, sunflower and others suffer. More heat-loving, such as cotton, melons, rice and corn, are not ignored. Greenhouse farms, and even ordinary summer residents, may lose crops of tomatoes and cucumbers because of this misfortune. Signs of tracheomycosis wilt can appear on radishes, peppers, and eggplants. Cabbage also suffers. An adult is less common, but its seedlings are extremely susceptible to "", which, in fact, is the same Fusarium. Asters, dahlias, carnations, petunias will not remain intact, clematis and roses will fall.

Forest nurseries are losing hectares of seedlings. In dense ridges, Fusarium spreads at the speed of a steppe fire.

Plants living in apartments did not escape the fate of "street" counterparts. Fusarium on indoor flowers, sorry for the tautology, is flourishing. He is always ready to spoil the mood by eating a collection of orchids and eating his favorite begonia. The Fusarium menu includes fuchsia, balsam, azalea, pelargonium, indoor and garden chrysanthemum, cyclamen ...

It’s easier to say which cultures do NOT get sick with fusarium.

Zinnia, gypsophila, periwinkle, mallow, ferns, ageratum, primrose and philodendron are invulnerable to him. Among indoor plants, only saintpaulia can resist, and from vegetables - asparagus ().

The risk is increased in acidic soils, especially with excessive moisture. Clay and heavy loam Fusarium does not favor, prefers that it is easier, that is, sandy loam. It almost never occurs in leached soils, except in the form of single spores.

Conditions for the development of fusarium

Until the middle of the last century, there was an opinion that Fusarium is dangerous only in greenhouses. Or in the south, where in summer daytime temperatures are kept within 25 - 28 degrees. Alas, over time, the pathogen moved deep to the north, and continues its march.

It is impossible to unequivocally state, they say: fusarium develops under the conditions of such and such. The combination of heat and high humidity is favorable for the mushroom itself. Plus, the presence of air in the soil, because the Fusarium is an aerobic organism, it also needs oxygen.

However, for many plants, the same conditions are optimal, therefore, their resistance is higher. Yes, the Fusarium does not come out the winner every time. Otherwise, only mushrooms would have remained on the globe ... a sad picture.

[!] General pattern: an outbreak of infection is provoked by those conditions that allow the Fusarium to develop, and at the same time inhibit the plants.

If there is stale air in the room, crowded plants, high humidity, and old soil in the containers, plus a lack of drainage, signs of fusarium will almost certainly appear.

Fusarium control

First of all, all contaminated soil must be changed. The one that will take its place should be etched with Trichodermin in advance. Instead, you can use: Fitosporin-M, Trichofit, Fitolavin, Gliocladin, Gamair, Previkur, Agat-25K, Alirin-B and others.

[!] Don't let the word "pickle" scare you: these biological preparations are completely safe. After their application, berries, fruits and vegetables are permissible to eat.

Caution is required by Bordeaux liquid, Vectra, Vitaros, Quadris, Skor, Maxim, Topaz, Oksihom, Bravo, Raek, Diskor and other fungicides of a chemical nature. But in advanced cases, when delicate biofungicides are powerless, they are needed. Instructions to help, children and pets - to another room, gloves on hands and go. Yes, do not forget about the respirator.

Boxes, pots, flowerpots and other containers must be disinfected. Wash well with soap and treat with bleach. Also sterilize the instrument.

The plant that has already fallen ill cannot be saved in ninety cases out of a hundred. In the remaining ten, they proceed as follows: cut off the stalk, see if the cut is clean. If dark, cut higher. And so on to healthy tissue. The stalk is soaked in a solution of one of the preparations (Fitosporin-M, Trichodermin, Maxim) and then rooted in calcined sand using biostimulants (Zircon, Kornevin and the like).

This way you can save phalaenopsis, azalea, and any home plant that the owner values ​​\u200b\u200band which is able to propagate by cuttings.

Fusarium prevention

Preventive measures are the alpha and omega of the fight against all fungal infections, including Fusarium. So:

1. Compliance with agricultural practices. Strong, healthy plants do not get sick with Fusarium.
2. Disinfection of soil, containers, tools and other garden props.
3. Destruction of diseased plants. Burn! Putting them in the compost heap makes it one big reservoir of Fusarium.
4. Acidified soils are neutralized by liming. A good option is ash or dolomite flour.
5. Don't stress the plants. This can be caused by a sharp change in conditions, shaking, movement, and in particular, rotation relative to the cardinal points.
6. Fusarium travels, "saddling" aphids, spider mites, whiteflies and other phytophages. Therefore, in the foreground is the fight against peddler insects.
7. Use of fusarium-resistant varieties. Almost every culture has these today.

By observing these, in general, simple rules, you can never meet Fusarium at all.

1

Among the topical environmental and hygienic problems in Russia and the CIS countries, a well-known place is occupied by fungal diseases of grain crops, in particular, head fusarium (FA) of winter wheat. Since the 80s In the 20th century, the distribution and harmfulness of Fusarium blight of winter wheat and barley, caused by the fungus Gerlachia nivalis (syn. F. nivale Сes.), is increasing in the Krasnodar Territory. The pathogen infects plants throughout the growing season as the causative agent (sometimes along with F. culmorum Sacc.) of "snow mold". The disease develops due to excessively early or late sowing; poor hardening of plants in autumn; high snow cover; late snowmelt; cold weather with frequent frosts and high relative humidity in spring, cold and rainy summer. The defeat is increased by the saturation of crop rotations with wheat and rye, grain predecessors, weediness of crops, uneven fields, and an excess dose of nitrogen fertilizers in the fall. In case of infection of plants with F. culmorum and F. graminearum, the affected leaf blade looks somewhat darker than when infected with a typical snow mold pathogen (F. nivale Ces.). In recent years, the same pathogens have been recorded as a leaf pathogen ("Fusarial leaf spot"). The source of infection is overwintered plants affected by snow mold. The ability to infect, along with leaves, an ear, grain and synthesize MT sometimes equalizes F. nivale and F. culmorum in terms of harmfulness with F. graminearum, which causes FC. The direct damage to the yield of ears is not always great, however, the vital activity of F. nivale contributes to the accumulation of nivalenol, deoxynivalenol (DON) and other mycotoxins (MT) in the grain.

Fusarium of cereal crops has become globally widespread. It has acquired the character of a pandemic and always develops under favorable weather conditions. The causative agents are fungi of the genus Fusarium Link.: F.graminearum, F.moniliforme, F.cul-morum, F.sambucinum, F.nivale, F.avenaceum. Fusarium of cereal crops is usually represented by F. graminearum, F. cumorum, F. nivale, F. avenaceum. F. graminearum prefers warmer and milder climates, while F. culmorum and F. avenaceum tolerate dry and cool conditions more easily. The disease affects all cereals, but Fusarium spike and wheat grains are especially common and harmful. The most intense infection occurs in the flowering phase of wheat. The defeat of FC (fungi of the genus Fusarium Link.) is manifested by yellowing of the ears, a spidery coating of mycelium of a pale pink hue on the scales with a transformation into merging pale pink or orange-red formations. A frail grain with loose endosperm causes losses of 25-30% or more of the yield, depending on the level of the primary manifestation of FC and the duration of the development of the disease until the phase of milky-wax ripeness. Procurement of fusarium grain in some years is 3-4 million tons. Mushrooms are able to continue development and infect grain at any stage of production - in windrows, on a current, during harvesting, transportation, storage (at a moisture content of more than 15%), processing, and during the manufacture of products.

The acquisition of toxic properties by grain during the periods of ripening and storage due to the accumulation of MT in it is a national economic problem. The main MTs of domestic Fusarium grain are DON and ZL. DON (vomitoxin) is produced mainly by various strains of F. graminearum, F. culmorum, F. nivale. The most active producer of ZL is F. graminearum, however, F. culmorum, F. moniliforme, F. nivale, F. tricinctum and other species also have the ability to synthesize it. MT concentrations are related to the content of fusarium grains, therefore, restrictions on the content of such grains have been introduced for grain crops.

Fusarium refers to difficult-to-predict diseases. Approximately a four-year cycle has been adopted for it. Since 1985, Fusarium of grain and ears has received a wide epiphytotic distribution in the territory of the former USSR and the Russian Federation, the maximum outbreak occurred in 1988-1989. with unusually wet conditions during grain ripening. The main ranges of Fusariums are located in the southern regions of Russia, in particular, on the territory of the Krasnodar and Stavropol Territories. The volume of harvesting of fusarium wheat increased many times over: from the harvest of 1989, 3980 thousand tons entered the state resources of the RSFSR, including 3708 thousand tons with a content of fusarium grains up to 1%; from 1 to 3% - 258 thousand tons and over 3% - 14.8 thousand tons.

The reasons for the spread of FA in the southern regions of the European part of the country can be not only warm, humid weather conditions during flowering, ripening and harvesting, but also the irrational use of intensive cultivation technology (minimization of soil cultivation, surface treatment with disc tools), substandard seeds, passion for late-ripening varieties , oversaturation of crop rotations with grains, especially wheat and corn, separate protracted harvesting. It is known that the placement of wheat over corn for grain, the overestimation of mineral nutrition (excess nitrogen) increase the susceptibility of plants to FA and contribute to the growth of the pathogen's harmfulness. The volumes of treatments with plant protection products are decreasing. In the Krasnodar Territory from 1988 to 1994. they decreased from 365.8 to 8.9 thousand hectares. The farms, referring to the difficult financial situation, refuse to process even potentially dangerous areas. Systematic exposure to pesticides can also increase the resistance and toxin-forming properties of FA pathogens.

The difficulty in preventing the spread of Fusarium is also associated with an acute shortage of fungicides that suppress FA. An important task remains the further search, development and study of these tools. In the practice of combating winter wheat fusarium, fungicides such as fundazol (benlat), impact (flutriafol), sportac (prochloraz), alto (cyproconazole), folicur (tebuconazole), tilt (propiconazole), rex KS (thiophanate methyl and epoxiconazole) have gained popularity , korbel (fenpropimorph), granite (bromuconazole), opus (epoxiconazole), etc. Improvement of the chemical method within the framework of integrated plant protection is aimed at selecting effective, but low-dangerous preparations for agrocenoses. When testing new and clarifying the effectiveness of recommended drugs, one should take into account their effect not only on the main pathogen, but also on associated microorganisms. Another side of the problem is the lack of FA-resistant wheat varieties. An effective means of combating FC is the use of agricultural techniques (crop rotation, deep plowing, incorporation of crop residues, etc.) in combination with chemical plant protection products.

Since the 1980s The distribution of wheat FA in the North Caucasus acquired an epiphytotic character, the development of the disease reached 40-70%. In such years, the disease manifests itself in cereal crops with an area of ​​up to 1.0-1.5 million hectares, the amount of contaminated grain reaches 4 million tons. 18%, and affected crops - 76%. Direct losses of marketable crops were estimated at 20-50% or more. Due to the high content of fusariotoxins, the grain was often unsuitable for use as food and forage. In 1989, the disease was found everywhere in the Krasnodar Territory, but with a lesser degree of development - up to about 20%. The range of FC covered all grain-sowing regions of the region and the Republic of Adygea (RA). Crops in the Central, Northwestern, Western, Southeastern and Piedmont zones were especially affected. The maximum spread of the disease (up to 17-31%) was noted in Starominsk, Tbilisi and Maykop regions (and in some fields - 100% with 70-80% damage to the ear). Fusarium wheat was contaminated with MT DON in 82-100% of cases. On the whole, in the RSFSR, 900 thousand tons of wheat (23% of the total mass of fusarium wheat) turned out to be unsuitable for use for food purposes in 1989 due to exceeding the permissible levels of MT, including 840 thousand tons in the Krasnodar Territory.

The prevalence of fusariotoxins in grain, their danger to human health caused the introduction of regulations for their content in food raw materials in 77 countries. In Russia, maximum allowable concentrations (MPCs) for MT of fungi of the genus Fusarium have also been established. For example, MPC for DON is 0.7 mg/kg in wheat and 1.0 mg/kg in barley. For ZL this figure is 1.0 mg/kg and for T-2 toxin - 0.1 mg/kg. Each species of Fusarium is capable of synthesizing a certain spectrum of MT. Taking into account the species affiliation of the pathogen fungus and determining the toxigenicity, it is possible to predict the contamination of Fusarium grain with specific MTs.

The species composition and properties of fusarium pathogens change markedly depending on the soil and climatic conditions of the zone. To characterize the phytosanitary situation, it is customary to take into account the dynamics of agrometeorological indicators that affect the state of agrocenosis and determine its variability in the future. At each stage of plant development, information is collected on the phytosanitary state of crops, which is used both to make decisions on the tactics of agrotechnical and protective measures, and to accumulate long-term materials on the impact of plant protection systems on the state of agrocenoses. When assessing the phytosanitary situation, the current information is compared with the data of long-term observations. These materials serve as the first and necessary step in improving plant protection. The next stage is the development of an algorithm for protective measures: agrotechnical, chemical or biological in terms of timing and direction of their action, depending on the state of the agrocenosis.

Weather conditions have a fundamental influence on the development and interaction of agrocenosis. It is known that with high snow cover and slow snow melting, snow mold develops more intensively, and the defeat of wheat FC depends to a decisive extent on the amount of precipitation, humidity and air temperature. FC mainly develops in those years when warm, humid, rainy weather prevails during the periods of earing, filling and ripening of grain. Of key importance may be the conditions that develop in a certain period of time ("critical periods"). Therefore, taking into account the meteorological situation is a mandatory condition for assessing and forecasting the phytosanitary situation. It makes it possible to predict the phenology and degree of development of pathogens, as well as the phenology and condition of plants, which is important for choosing the tactics of preventive and protective measures. Phytosanitary diagnostics uses four forms of meteorological information: characteristics of the climatic features of the region; characteristics of the weather features of the past year (season); indicators of temperature, precipitation, soil and air humidity for specific periods of time of the current season; weather forecasts of different lead times. Climate data are averages of its main characteristics over a long period: average annual indicators of the sum of temperatures and the sum of precipitation; the average timing of the onset of the seasons of the year and deviations from them; temperatures and rainfall in each season. Air temperature, precipitation, air humidity, intensity and duration of sunlight, and other data are subject to registration. For winter crops in the cold season, the temperature of the soil in the zone of the tillering node, the depth of freezing and the timing of thawing of the soil, snow cover, and the condition of plants are taken into account. Quantitative relationships between indicators of the state, efficiency of plant protection and meteorological factors are established by statistical methods at the next stage by analyzing the information accumulated over a number of years.

The main causative agent in the southern regions of the CIS (Krasnodar, Stavropol Territories and Ukraine) is F. graminearum, in the non-chernozem zone F. avenaceum and F. culmorum are close to it in terms of pathogenicity, symptomatic manifestations and harmfulness. The dominance of F. graminearum over other species and the impoverishment of the species composition of the population increased in long-term foci of the disease. In the North Caucasus region and specifically on the territory of the Krasnodar Territory, F. graminearum, gradually replacing related species, is, according to various sources, from 76-87 to 90% of the Fusarium population. All 12 strains isolated from Fusarium grain in the North Caucasus produced DON and ZL, although the levels of their toxigenicity varied widely: 1.3–4820.0 mg/kg DON and 2.3–384.0 mg/kg ZL. Apparently, the population of F. graminearum, which causes grain fusarium in the southern regions, produces predominantly DON and GL, as well as FA pathogens in Canada and the USA. Representatives of another chemotype F. graminearum, common in Southeast Asia, synthesize nivalenol along with DON, which is a more dangerous combination due to the high toxicity of the latter. Other MTs (T-2 toxin, DAS) are almost not produced by this species.

The toxigenicity of F. graminearum depends on the geographical origin of the strains. In the Krasnodar and Stavropol Territories and North Ossetia, most of the isolates produced DON in amounts less than 200 mg/kg. SL was accumulated by fungi in smaller amounts than DON. In all zones, except for North Ossetia, weak DL producers predominated, forming up to 50 mg/kg of the toxin. The North Ossetian population was the most toxigenic: 48% of the strains of the population produced more than 200 mg/kg ZL. High toxigenicity of F. graminearum isolates from Azerbaijan was established, synthesizing up to 10000 mg/kg ZL. It is possible that the foothill agro-climatic conditions favor the acquisition of F. graminearum properties for the synthesis of high concentrations of PLs. This potential danger, obviously, it is expedient to investigate in the foothill zone of the Krasnodar Territory.

If we take as a measure of the harmfulness of Fusarium, the DON concentrations per 1% of Fusarium grains in the grain mass, i.e. the ratio of the amount of DON to the content of fusarium grains, then in the Krasnodar Territory it was 1.02-1.08 and varied slightly depending on the year. In other zones of the southern region, fusarium blight was less harmful, the ratio of DON/fusarium grain blight was noticeably lower on average (0.58 and 0.71). It can be assumed that the Krasnodar Fusarium population consists mainly of F. graminearum, all strains of which are capable of synthesizing DON, while the Fusar populations in the Stavropol Territory and Ukraine are more diverse and include species that are not active producers of DON.

Bibliography

1. Donchenko L.V., Nadykta V.D. Food safety. - M.: Pishchepromizdat, 2001. - 528 p.
2. Zakharenko V.A., Novozhilov K.V., Goncharov N.R. Collection of methodological recommendations for the protection of plants. - St. Petersburg, 1998. - 299 p.
3. Lvova L.S., Omelchenko M.D., Orlova N.Yu., Bystryakova Z.K. Fusarium wheat mycotoxins. Peculiarities of its acceptance, storage and processing // Survey information. - Ser.: Elevator industry. - M.: TsNIITEM bread production, 1992. - S.1-44.
4. Monastyrsky O.A. Current state and problems of the study of toxinogenic fungi affecting cereal crops // Topical issues
   biologization of plant protection. - Pushchino, 2000. - S.79-89.
5. Tutelyan V.A., Kravchenko L.V. Mycotoxins (medical and biological aspects). - M.: Medicine, 1985. - 320 p.
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Bibliographic link

Grushko G.V., Linchenko S.N., Khan V.V. CHARACTERISTICS AND CONDITIONS OF THE DISTRIBUTION OF FUSARIIA EARS ON WINTER WHEAT CROPS OF THE SOUTHERN REGIONS OF RUSSIA // Modern problems of science and education. - 2005. - No. 2.;
URL: http://science-education.ru/ru/article/view?id=1514 (date of access: 03/28/2020). We bring to your attention the journals published by the publishing house "Academy of Natural History"

Fusarium is a worldwide problem. Diseases resulting from the infection of various cereal crops by certain species of pathogenic fungi of the genus Fusarium are among the most serious and potentially devastating diseases throughout the world, and especially in the regions of the USA, Canada, Argentina, Australia and Europe, incl. Ukraine engaged in the cultivation of wheat. Since the beginning of the 1990s, there has been a sharp increase in the incidence of diseases caused by a pathogenic fungus of the genus Fusarium. The risk of infection has increased due to changes in cropping practices: for example, the increasing use of minimum tillage technology; an increase in the frequency of sowing grain crops in the crop rotation, as well as as a result of an increase in the area under corn. Infectious lesions caused by a pathogenic fungus of the genus Fusarium can occur at the base of the stem, on leaves and on ears. The greatest damage is caused if the pathogenic fungi Fusarium graminearum and F. culmorum infect the ear. Since these pathogenic fungi produce mycotoxins, they can be a direct reason for limiting the use of contaminated grain for food and feed production. Mycotoxins are dangerous for humans and animals Fusarium spike leads to a decrease in the weight of a thousand grains and the number of grains per ear, and also reduces the viability of seeds. Yield losses can reach more than 50%. This disease also reduces the baking quality of flour and can adversely affect the brewing process when infected barley is used. However, an even more important factor is the ability of the pathogenic fungus Fusarium to produce mycotoxins, i.e. products of the metabolic processes of the fungus, which are toxic to humans and animals and can cause serious damage to the body, even in small concentrations. The most dangerous fusariotoxins, which are produced on cultivated cereal balls, are nivalenol, deoxyn-valenol - mainly on wheat, triticale and barley. Wheat, barley and rye are especially vulnerable. Typical symptom: discolouration of the ear Infection or re-infection with F. graminea rum and F. culmorum results in discolouration of the ear or a whole group of colossi. Brown-violet coloration is also often observed on the central axis of the ear. If the weather conditions are favorable for the development of the fungus, then at the base of the spike and at the edges of the spike scales, spore bodies are formed, the color of which ranges from orange-red to pink. Symptoms of the disease may differ, depending on which of the cereal crops is affected by this disease - wheat, triticale, oats, rye, spring or winter barley. Infection with conidia and ascospores. Pathogens, predominantly in the form of conidia and ascospores, overwinter in the fields on dead plant debris such as straw and stubble. Conidiospores can infect the ear after being sprayed from letter to letter up along the stem by raindrops, but wind-blown ascospores also play an important role in directly infecting the ear. Ascospores develop in fruiting bodies called perithecia. These fruiting bodies are formed on infected organic residues located on the soil surface. Over time, the perithecia mature and scatter ascospores. If cold and wet weather persists for a long time after spore release, an asymptomatic increase in the number of spores may occur. Because ascospores can only spread over very short distances, the source of infection in a particular field is usually a potentially infected object present in that field. The risk of infection depends on whether crops are near the epicenter of infection at the time of spore release. The most susceptible to them is the flowering phase, when the pathogen has just matured its spores, they easily penetrate into the plant tissues. The main routes of infection are anthers, ovaries, and the inner surface of the glumes. After successful infection, the mycelium of the fungus begins to develop inside the plant tissue towards the stem. With a strong infection, the pathogen produces a large amount of mycelium, which is deposited in the vascular-conducting system of the stem. As a result, partial or complete discolouration of the spike or white spike occurs. The degree of infestation depends on weather conditions and pathogen potential. The most important factor influencing the incidence of Fusarium infection is the forerunner, tillage quality, variety selection, weather conditions and fungicide use. Two of these factors, precursor and tillage, have a recent influence on the amount of pathogen accumulation potential. The combination of the initial pathogenic potential and weather conditions, in turn, determines the accumulation of the pathogen, which can later lead to the appearance of fusariosis of the ear. The danger of Fusarium infection also depends on the perception of agricultural (development stage / resistance of the variety) and the timing of the application of fungicides. Variable and rainy weather during the heading period is especially conducive to the occurrence of infection. In order for destructive pathogens such as fungi of the genus Fusarium to infect the plant, they only need a wet period of 24 to 40 hours at temperatures above 20°C. ° C during the flowering period of wheat, there can be a very high risk of an outbreak. Different types of Fusarium fungus differ mainly in the requirements for the temperature at which infection occurs (F. culmorum: 16-18 ° C; F. graminearum: 20-22 ° C). Warm and humid weather between flowering and maturation of crops, combined with their late harvest, creates preconditions for the spread of pathogens and contamination of grain with toxins. Main source of infection: maize stubble in short rotation crop rotation. Stubble, as well as other plant residues that remain on the soil surface, especially corn stalks, which are difficult to decompose, are a source of infection throughout the growing season; thus, the risk of infection of further crops is increased. So, tillage with minimal mechanical action contributes greatly to the occurrence of infection: depending on the technology used and the method of cultivation, most of the plant residues remain on the surface of the soil and in its surface layer. According to a study in France, after harvesting wheat planted by direct seeding after corn, the content of deoxynivalenol in it was four times higher than that of wheat sown after ploughing. For minimum tillage, the content of toxins in the soil was twice as high as for plowing. It is absolutely clear that the incorporation of stubble into the soil by plowing significantly reduces the risk of infection. However, the stubble, which was previously in the soil and during the plowing process, returned to the surface of the soil during preparation of the soil for the subsequent crop, still remains a source of infection if it is not completely overripe. The greatest risk of infection is if wheat is sown by direct seeding after corn. The second very risky method, although with a much lower degree of risk, was hanging wheat by direct sowing in the stubble after the predecessors of cereal grains. Different strategies must be used to reduce infestation. Farmers need to apply certain agronomic measures to avoid infection of crops with Fusarium fungus, since the crop should not contain toxins in concentrations exceeding the acceptable level of infection. Depending on location and other factors, the following measures should be taken to reduce infection: Careful crop selection in rotation: Reduce the amount of corn or grains in long rotation rotations.

Variety selection: growing varieties with less susceptibility to Fusarium fungus; Stubble incorporation: plowing the soil reduces the risk of infection; also grinding and uniform distribution of plant residues of agricultural crops accelerates the process of their decomposition in the soil with the help of microorganisms (which proceeds even faster when ammonia urea is added to the soil);

Carrying out top dressing of agricultural household balls round: underdevelopment of the crop and lodging (both of these phenomena can increase the susceptibility of plants to infection) should be avoided by applying fertilizers in accordance with the requirements for specific crops. Harvesting the crop as soon as the grain has reached the required stage of maturation (sufficiently low moisture content);

Application of plant protection products: use of fungicides.

Treatment of seeds with disinfectants, spraying leaves and ears with appropriate preparations (which include such active ingredients as tebuconazole, prothioconazole: Lamardor, Raxil Ultra, Falcon, Folicur), which reduce infectious loads. Effective fungicides are already available, but weather conditions remain the main factor that determines the appearance of infection. If conditions are conducive to infection, farms have little choice but to use fungicides to control Fusarium to reduce infection and, most importantly, to reduce mycotoxin production. When the lesions caused by this pathogen are already present at the time of processing the leaves, it makes sense to use a preparation containing components that are effective against the Fusarium fungus - Falcon, Folicur. Such actions can lead to a significant reduction in infection by these pathogens and a decrease in mycotoxin contamination. According to the results of tests, during which the ears of cereal crops were treated with azole fungicides (containing components such as tebuconazole or prothioconazole as the active substance), it was clearly proved that when the crops were treated at the appropriate time, the degree of damage by ear fusarium, and, accordingly, the level of infection with the toxin , can be significantly reduced. In field trials spanning several years in France, Germany and the UK, Falcon significantly reduced infections with the pathogenic fungus Fusarium in more than half of the wheat varieties studied, and also reduced the content of deoxynivalenol in grain by an average of 50%. The timing for processing is highly dependent on the species of pathogenic fungus Fusarium and the weather conditions required for infection. All this means that the time for optimal treatment of crops with fungicides is limited. The best time to apply drugs during flowering is after one to two days from the moment of infection with a pathogen. First of all, after rain, after the beginning of the appearance of the ear (when about 30-40% of the ears appeared). Spraying efficiency may be less if it is carried out only a few days earlier or later than necessary. Tests carried out over a period of several years have shown that the optimal time to use the preparations is, on average, within three days before flowering and three days after flowering. However, the occurrence of infection caused by the pathogenic Fusarium fungus can be successfully reduced with the use of Falcon.