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The most famous infectious diseases of agricultural plants. Mass destruction of agricultural plants by infectious diseases. The concept of natural disasters

Epiphytoty is a mass, progressing in time and space, infectious disease of agricultural plants and (or) a sharp increase in the number of plant pests, accompanied by mass death of agricultural crops and a decrease in their productivity.

Panphytoty is a mass plant disease and a sharp increase in the number of plant pests in several countries or continents.

Epiphytoties include:

rust of cereals, with the defeat of which yield losses are 40-70%;

rice blast - the disease is caused by a fungus, yield losses can reach 90%;

late blight (potato rot) - a disease that affects the leaves, stems and tubers of potatoes, etc.

The death and disease of plants can be the result of improper use of various chemicals, for example, herbicides, defoliants, desiccants, which are used to destroy weeds and wild shrubs during the development of new lands, removing or drying the leaves of agricultural plants before harvesting, as growth and maturation stimulants.

Locusts cause incomparable damage to agriculture in many countries of Africa, Asia and the Middle East. 20% of the surface is exposed to its raids the globe. Locusts, moving at a speed of 0.5-1.5 km / h, destroy literally all vegetation on their way. So, in 1958, one flock destroyed 400 thousand tons of grain in Somalia in a day. Trees and bushes break under the weight of settling swarms of locusts. Locust larvae feed 20-30 times a day.

Serious pests of agriculture are rodents (marmots, ground squirrels, gray voles, etc.). During mass reproduction, their numbers can increase by 100-200 times. This increased number of rodents requires a huge amount of food, which becomes agricultural crops, especially cereals.

Outbreaks of the spread of biological pests occur constantly. The Siberian silkworm causes great harm to forest plantations. Hundreds of thousands of hectares of coniferous taiga, primarily cedar, died from it in Eastern Siberia. Termites are extremely harmful to buildings, vegetation and food. There is a known case of the destruction by termites of the city of Jonestown on about. Saint Helena.

The main actions aimed at preventing plant diseases are deratization, disinfestation, biological, chemical and mechanical pest control in agriculture and forestry (spraying, pollination, surrounding the centers of pest distribution with ditches).

In the event of an epiphytoty, phytopathological reconnaissance is organized, which conducts a survey of agricultural land, places of storage and processing of products plant origin and the territory adjacent to them, establishes the type of pathogen and the boundaries of infection zones.

The main measures to protect plants from infectious diseases are:

breeding and cultivation of disease-resistant crop varieties;

compliance with the rules of agricultural technology;

destruction of foci of infection;

carrying out quarantine measures;

chemical treatment of crops, sowing and planting material and etc.

Rescuers are involved in work in conditions of epiphytosis in the event that it assumes menacing proportions.

Means of destruction of agricultural plants biological

pathogenic microbes, in which the active principle is spores of stem rust of wheat, rye, yellow rust of wheat and late blight of potatoes, as well as insects - carriers of these microbes or pests that can cause mass destruction of crops.


Edwart. Glossary of terms of the Ministry of Emergency Situations, 2010

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MINISTRY OF EDUCATION OF THE REPUBLIC OF BELARUS

Educational Establishment "Mogilev State University

them. A.A. Kuleshov"

Department of Physics and Technical Disciplines

ESSAY

Damage to agricultural plants and forests by diseases and pests

Mogilev 2010

    The concept of epiphytoties

    Forest pests and diseases

    Pests of agricultural plants

The concept of epiphytoties

Infectious plant diseases differ significantly from each other not only in pathogenesis and external manifestation, but also in the nature of their development in nature. Some diseases are ubiquitous, but rare, and the level of their occurrence remains almost unchanged. Other diseases are more common, but also little subject to fluctuations; mass development of these diseases over large areas and severe damage to plants that pose a threat to crops or plantations is not observed. Such diseases include many types of stem rot of tree species, damping off of seedlings and a number of other diseases.

At the same time, there are diseases, the distribution and development of which in a certain area or within the entire range is not constant, subject to sharp fluctuations. These are the many types of rust and powdery mildew, some types of vascular diseases and root rot of tree species, a number of viral and other diseases.

The mass development of an infectious plant disease in a certain area over a certain period of time is called epiphytoty. The study of epiphytoties occupies a special section of phytopathology - epiphytotiology. This is the study of the development of pathogen populations within host populations and of plant diseases resulting from their interaction under the influence of the environment or human intervention.

The role of the pathogen, host plant and environment in the development of epiphytoties

The emergence, development and decay of epiphytoties, as well as the dynamics of diseases in general, obey certain patterns and depend on the interaction of three components involved in the epiphytotic process: the pathogen population, the disease, the host plant population, and the environment. If this interaction is favorable for the development of the disease, it progresses and epiphytosis occurs. If the course of epiphytoties creates conditions that prevent its further development, its gradual attenuation occurs, the outbreak of the disease stops. Each of these components plays a specific role and is equally important.

The role of the pathogen. The role of the causative agent of the disease is exceptionally great. For the occurrence of epiphytoties, it is necessary that the pathogen has high aggressiveness and virulence in relation to the host plant growing in the area and that the stock of infection is large enough. The decisive prerequisite for epiphytoties may be the emergence of a highly aggressive pathogen, new to the area, with high fecundity and the ability to accumulate in nature.

The higher the rate of reproduction of the pathogen, the easier and faster it spreads, the longer it is able to survive without losing viability, the greater the threat of epiphytoties. And, conversely, a reduction in the stock of infection, a decrease in the energy of reproduction and the rate of spread of the pathogen, a decrease in its aggressiveness are the most important prerequisites for the attenuation of epiphytoties.

The role of the host plant. It is also very significant. The mass development of the disease occurs only if a large number of susceptible plants are concentrated in a certain area. The significance of this factor increases when the development cycle of the pathogen proceeds on two different host plants, which is observed in rust fungi of different hosts. In this case, for the occurrence of epiphytoties, the presence of both host plants in sufficient quantities is necessary. Therefore, the removal of the intermediate host can be a decisive condition for stopping the further development of rust.

Weeds play a very important role in the accumulation of infection and the development of epiphytoties, on which pathogens of cultivated plants and forest species can multiply and persist. The role of the host plant during introduction is especially great: if the imported plant species is susceptible to local pathogens, then with time the development of these diseases on the new host can acquire the character of epiphytoties. The same thing happens if a pathogen, getting into new areas, finds new susceptible hosts there.

The host plant can also play an important role in the attenuation of epiphytoties. If the epiphytoty is seasonal, then age-related changes in plants or their tissues can contribute to its attenuation, due to which the plants acquire resistance, as is observed, for example, with lodging of seedlings or oak powdery mildew.

A general increase in the stability of plantings under the influence of changes in external conditions or as a result of natural selection can also be a factor in the attenuation of epiphytoties, since the most stable or hardy individuals survive in the population. Finally, epiphytosis can stop when resistant plant species or forms are introduced into the culture.

The role of the environment. This role is often decisive. Especially great importance have the climatic conditions of the area and the weather conditions of a given year, sometimes several recent years. The determining moment in this case is, as a rule, not one factor (for example, optimal temperature or humidity), but the optimal combination of many factors that favor the mass reproduction of the pathogen, its accumulation and spread, and infection of plants. Environmental factors can contribute to the emergence of epiphytoties even if they have an adverse effect on the host plant, causing its weakening and thereby reducing its resistance to the disease. And, conversely, any conditions that prevent the accelerated reproduction and preservation of the pathogen in nature, its rapid spread and infection of plants, as well as all factors that increase the viability and resistance of the host plant, can be factors in the attenuation of epiphytoties.

Thus, epiphytosis is a complex set of interrelated elements that are continuously changing under the influence of many factors: genetic, environmental, economic, etc. These elements form in time and space, as it were, a continuous chain, and its individual links and the nature of the connections between them are determined by the specifics of the relationship in the pathogen-host system and the characteristics of the environment.

Dynamics of epiphytoties

Epiphytoty is a dynamic process, in the development of which a number of successive stages are distinguished: 1) a preparatory stage, or pre-epiphytoty; 2) an outbreak of a disease, or an actual epiphytoty; 3) stage of depression, or attenuation of epiphytoties.

During the first stage, those changes in the populations of the pathogen and the host plant occur in nature, which then lead to an outbreak of the disease: the appearance of new, more aggressive races of the pathogen or more active, due to optimal weather conditions, reproduction and accumulation of the pathogen already present in the area , the concentration of susceptible plants over large areas (for example, when creating pure forest cultures) or a decrease in the stability of plantations for one reason or another; the emergence of favorable conditions for plant infection (for example, in connection with human economic activity, increased recreational loads or the impact of abiotic factors, etc.). The duration of this stage can vary, but most often it lasts for several years.

The second stage (outbreak) is characterized by a simultaneous lesion a large number plants, a strong degree of damage and death of a significant part of diseased plants, a high level of damage caused by the disease. The climax of the outbreak can be timed to a certain age of plants or to the period with the most favorable weather conditions for the development of the disease.

During the third stage (depression), there is a gradual decrease in the number of diseased plants and the degree of their damage. The zone of distribution of epiphytoties usually also decreases.

The duration of epiphytoties, as well as its individual stages, depends on many factors and can fluctuate greatly. Epiphytotics of some diseases develop during one season, others can last for many years.

The processes occurring in interacting populations of pathogens and host plants are described and explained by mathematical models. Mathematical modeling of epiphytoties is considered in the works of Van der Planck and other authors. Models of population changes over time are used to analyze population parameters, assess the development and predict epiphytoties.

Types of epiphytoties

Depending on the characteristics of development and the extent of distribution in nature, the following main types of epiphytoties are distinguished:

Local epiphytoties, or enphytoties. They are characterized by an annual (over several years) strong development of the disease in a limited area, sometimes in the form of separate foci. The causative agents of local epiphytoties, as a rule, are constantly present in the area. They are able to persist for a long time in the soil, on plant residues, seeds, weeds, etc. The infective onset of such pathogens usually accumulates slowly in nature and spreads relatively slowly. However, if the stock of infection reaches a high level, then in the presence of susceptible plants and favorable external conditions, epiphytoties often occur. An example of local epiphytoties is the lodging enphytoties observed annually in nurseries in many regions of the country.

Progressive epiphytoties. Epiphytoties of this type start as local, but over time cover larger areas. They are usually caused by the most aggressive pathogens that have a high reproductive energy, form several generations of asexual sporulation during the summer, and are able to spread rapidly through the air or with the help of insects (for example, epiphytoties of rust, powdery mildew, some vascular and viral diseases).

The reason for the occurrence of progressive epiphytoties may be the transfer of infected planting material from one area to another or the pathogen entering new areas for it, where there are significant areas of susceptible host plants. An example of such an epiphytoty is the epiphytoty of Weymouth pine blister rust, which arose and quickly covered vast areas occupied by this pine in the USA after the pathogen was brought to America from Europe.

Progressive epiphytoties often develop over many years. In young pine cultures created on vast areas of concentrated clearings in the northern and northwestern regions of Russia, progressive epiphytoties of snow shute and rust of pine shoots are observed.

Widespread epiphytoties, or panphytoties, are characterized by the massive development of the disease on the territory of an entire country, sometimes several countries or continents. Panfitotia is a rather rare phenomenon, but they can take on the dimensions of a national disaster, as happened during the panfitotiya of potato late blight in the middle of the 19th century. At the beginning of the XX century. the nature of panphytoty was the mass distribution of powdery mildew of oak and powdery mildew of gooseberry, brought from America to Europe. The ubiquitous distribution of the root fungus in many countries of Europe and North America has also reached the level of panphytoty over the past decades.

In addition, there are slowly developing, or tardive, and rapidly developing, or explosive, epiphytoties. The former are most often observed when perennial plants (for example, woody) are affected by diseases such as Dutch elm disease or root rot on conifers. They are characterized by a smooth rise of the flash and its gradual attenuation. The latter are caused mainly by pathogens with a high reproduction rate and are characterized by a sharp increase in the outbreak and its rapid attenuation. The course of epiphytoties of this type is often subject to seasonal changes and is largely determined by environmental factors. Examples are the epiphytotics of apple scab, seedling lodging, powdery mildew, rust, schütte, and other agricultural uses. Law >> Ecology

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    • epiphytoty is a mass, progressive in time and space, infectious disease of agricultural plants and (or) a sharp increase in the number of plant pests, accompanied by mass death of agricultural crops and a decrease in their productivity.

    panphytoty called a mass plant disease and a sharp increase in the number of plant pests in several countries or continents.

    Epiphytoties include:

    Rust of cereals, in the defeat of which yield losses amount to 40-70%;

    Rice blast - the disease is caused by a fungus, yield losses can reach 90%;

    late blight (potato rot) - a disease that affects the leaves, stems and tubers of potatoes, etc.

    The death and disease of plants can be the result of improper use of various chemicals, for example, herbicides, defoliants, desiccants, which are used to destroy weeds and wild shrubs during the development of new lands, removing or drying the leaves of agricultural plants before harvesting, as growth and maturation stimulants.

    Locusts cause incomparable damage to agriculture in many countries of Africa, Asia and the Middle East. Its attacks affect 20% of the surface of the globe. Locusts, moving at a speed of 0.5-1.5 km / h, destroy literally all vegetation on their way. So, in 1958, one flock destroyed 400 thousand tons of grain in Somalia in a day. Trees and bushes break under the weight of settling swarms of locusts. Locust larvae feed 20-30 times a day.

    Serious pests of agriculture are rodents (marmots, ground squirrels, gray voles, etc.). During mass reproduction, their numbers can increase by 100–200 times. This increased number of rodents requires a huge amount of food, which becomes agricultural crops, especially cereals.

    Outbreaks of the spread of biological pests occur constantly. The Siberian silkworm causes great harm to forest plantations. Hundreds of thousands of hectares of coniferous taiga, primarily cedar, died from it in Eastern Siberia. Termites are extremely harmful to buildings, vegetation and food. There is a known case of the destruction by termites of the city of Jonestown on about. Saint Helena.

    The main actions aimed at preventing plant diseases are deratization, disinfestation, biological, chemical and mechanical pest control in agriculture and forestry (spraying, pollination, surrounding the centers of pest distribution with ditches).



    In the event of an epiphytoty, phytopathological reconnaissance is organized, which conducts a survey of agricultural land, places of storage and processing of plant products and the territory adjacent to them, establishes the type of pathogen and the boundaries of infection zones.

    The main measures to protect plants from infectious diseases are:

    breeding and cultivation of disease-resistant crop varieties;

    Compliance with the rules of agricultural technology;

    · destruction of the centers of the arisen infection;

    Carrying out quarantine measures;

    chemical treatment of crops, seed and planting material, etc.

    Rescuers are involved in work in conditions of epiphytosis in the event that it assumes menacing proportions.

    Life safety as a branch of knowledge. Dangers and their sources.

    BJD as a branch of knowledge.

    natural hazards.

    anthropogenic hazards.

    social dangers.

    BJD as a branch of knowledge.

    BJD- the science of human safety in the environment.

    The purpose of the study is to study dangerous factors environments and development of protection against them.

    The history of the Belarusian Railway begins from ancient times.

    AT Ancient Greece and Rome, doctors drew attention to the disease of "mining workers", linking the state of health and working conditions of people. In the Middle Ages and the Renaissance were known " occupational diseases”, for example, “the disease of the old hatter”.

    In the 19th and 20th centuries, new theories appeared that provided the basis for improving working conditions and reducing the working day.

    In the 2nd half of the 20th century, the disciplines "Labor protection", "Civil defense" appeared. At the end of the 20th century, BJD became isolated as a science.

    Man and environment.

    The relationship between man and the environment (direct and reverse).

    THE CONCEPT OF NATURAL EMERGENCIES.

    The concept of an emergency (ES) natural origin in accordance with the text of the Federal Law “On the Protection of the Population and Territories from Natural and Man-made Emergencies” can be formulated as an unfavorable situation in an indefinite territory resulting from a dangerous natural phenomenon, a natural disaster that may or have caused human casualties, damage to human health , environment significant material losses: and violations of people's livelihoods.

    Thus, natural emergencies develop under the influence of natural hazards(natural Disasters).

    Under a dangerous natural phenomenon we will understand a spontaneous event of natural origin, which, due to its intensity, the scale of distribution of duration, can cause negative consequences for the life of people, the economy of the natural environment.

    What dangerous natural phenomena occur on the territory of our country and in other countries of the world?



    2. Classification of natural emergencies

    Scientists divide these phenomena into 10 groups (classes) depending on the mechanism of their origin.

    Not every dangerous natural phenomenon leads to an emergency, especially if there is no threat to human life at the place of its occurrence. So, for example, an annual flood is not counted as a flood if it does not threaten anyone. There is no reason to consider storms, storms, avalanches, freezing, volcanic eruptions as emergency situations in those places where a person does not live and does not carry out any work.

    An emergency occurs only when, as a result of dangerous natural phenomenon arises real threat man and his environment.

    emergency NATURAL nature are classified (systematized) into several types and types.

    Geophysical hazards.

    These include earthquakes and volcanic eruptions. Since these phenomena are due to internal tectonic processes of the Earth's development, they are called endogenous.

    Geological (exogenous) hazardous phenomena.

    Unlike internal endogenous geophysical phenomena, they entirely originate and develop on the surface of the Earth, destroying rocks that have come to the surface of the earth's crust as a result of endogenous processes.

    Exogenous phenomena include: landslides, mudflows, landslides, screes, avalanches, slope washout, subsidence of rocks, erosion (destruction of rocks by water, wind, man), abrasion (destruction of coasts by waves), dust storms.

    Meteorological and agrometeorological hazards.

    These are phenomena associated with atmospheric processes (changes in pressure, humidity, temperature and air velocity):

    Storms, hurricanes, tornadoes (tornadoes), squalls; heavy precipitation (rain, hail, blizzard, ice); hard frost, frost; extreme heat, drought, dry wind.

    4. Marine hydrological hazards:

    Tropical cyclones (typhoons); extratropical cyclones (hurricanes); strong sea waves (5 or more points);

    strong tidal waves, drafts (dangerous wave fluctuations in ports); icing of ships and structures; strong pressure and drift of ice, separation of ice floes; impenetrable ice.

    5. Hydrological hazards:

    High water levels - floods (floods, wind surges, traffic jams, ice jams, floods);

    Low water levels;

    Early freezing, the appearance of ice on navigable reservoirs and rivers.

    Hydrogeological hazards: lower or higher levels ground water.

    7. Natural fires: forest, steppe, field (grain massifs), peat, fossil fuels (coal, shale).

    Infectious morbidity in humans: epidemics, pandemics, dangerous infections.

    Infectious morbidity of farm animals: epizootics, enzootics, panzootics, etc.

    The defeat of agricultural plants by diseases and pests: epiphytoties, panphytoties, mass distribution of pests.

    It should be noted that many hazardous natural phenomena are closely related to each other. So, for example, an earthquake can cause collapses, landslides, mudflows, floods, tsunamis, avalanches, and activation of volcanic activity. Many storms, hurricanes, tornadoes are accompanied by showers, thunderstorms, hail. Extreme heat is accompanied by drought, lowering of groundwater, fires, epidemics, and pest invasions. Try to more fully trace these connections and the mechanisms of their formation in the study of individual topics.

    On the territory of our country there are all kinds of dangerous natural phenomena. There is no area where they are not. Each city, district (krai, region, republic) has its own characteristic differences in the types, frequency and scale of hazardous natural phenomena. For example, on the ocean and sea coasts, these phenomena occur more often than in the central regions of Russia. But here, centuries-old observations have shown a fairly frequent occurrence of emergencies. This is evidenced by a table compiled by scientists based on the results of studying all Russian chronicles and other historical sources for a thousand years.

    Studying this table, pay attention to such a type of emergency as famine years. The then level of agriculture and food storage technology did not ensure the creation of large food reserves. Therefore, such an increased attention of chroniclers was caused by rainy summers, frosts and returns of cold weather in summer. In ancient times, these were the most dangerous phenomena. They ruined the harvest, doomed people to hunger, disease, epidemics. With today's advances in agriculture, food processing and medicine, these dangers have somewhat decreased. But the changed density and height of buildings, the multiple increase in the population in potentially dangerous areas brought to the fore in their consequences such dangerous phenomena as earthquakes and floods.

    In addition, when analyzing the data of the table, especially for X-XIV centuries

    Dangerous natural phenomena recorded in Russian historical sources of the 10th-19th centuries.