Widespread disease. It affects more than 150 plant species, including cotton, vegetables (tomatoes, cucumbers, cabbage), potatoes, grains (wheat, barley), flax, alfalfa, hemp, tobacco, shag, etc.
When affected, brown, almost black, stripes (root rot) appear on the roots and basal part of the stem, which, in conditions of high humidity, become covered with a white or slightly pink coating of sporulation of the fungus, consisting of mycelium, conidiophores and conidia. Conidia are colorless, sickle-shaped, with 3-5 transverse septa. Plants wilt and are easily pulled out of the soil. On the cut of the stems, darkening of the vessels is noticeable. The crop loss due to disease usually reaches significant proportions - at least 60%.
The causative agent is the fungus Fusarium oxysporum, which belongs to the order of hyphomycetes, a class of imperfect fungi. The presence of specialized forms and races associated with certain host plants has been noted.
The main factor in the transmission of the pathogen is soil. Like the wilt pathogen, the fungus enters the plant through root system, and then spreads through the vessels. With a high initial population of the pathogen in the soil, the disease is especially dangerous when infecting plants in the early phases of their development.
The seasonal dynamics of the epiphytotic process during the transmission of the pathogen through the soil in the graphical representation resembles an S-shaped curve, which, depending on the resistance of the variety in different times reaches a plateau: when cultivating resistant varieties, much earlier and with a lower overall level of disease development than when cultivating susceptible varieties. The higher the population density of pathogen propagules in the soil, the higher the degree of disease development. The quantitative indicators of this pattern on different crops and soils with different suppressive conditions are not the same. According to S. Smith and V. Snyder, a very strong development of fusarium blight on sweet potato was noted when there were 5 thousand chlamydospores in 1 g of soil, while it was not registered with 50 diseased plants.
French scientists have shown that on suppressive soils there was no infection of pumpkin, cabbage and tomato by the pathogen even in the presence of 2400 propagules/g of soil. On conductive soils, plants died starting with 50 or more propagules/g of soil. The general theoretical index of soil colonization by F. oxysporum and F. solani is higher in conductive soil than in suppressive soil. The addition of glucose at a concentration of 0.1 mg/g was sufficient to increase the population of Fusarium species in conductive soil by 1.5 times. For such population growth in suppressive soil, the glucose concentration must be 10 times higher. This is due to the fact that the level of fungistatic action is higher in suppressive soil and is due, according to the authors, to competition of microbes for energy sources.
Soil suppressiveness is largely due to biotic factors. In some agroecosystems, the suppressors were saprotrophic fungi growing quickly in the soil - Mucor plumbeus, M. hieinalis, Trichoderma viride, Penicillium sp.; when they are introduced into the soil in combination and separately, suppression of fusarium blight of grain legumes is noted. However, in other environmental conditions, for example, on tomato plantings, soil suppression was caused mainly by the bacteria Bacillus subtilis, and on flax crops - Pseudomonas spp., on potatoes and other crops - Trichoderma harzianum alone or in combination with Aspergillus ochraceus, Penicillium Funicolosum. At a concentration of antagonists of 5·10 5 soil, the population density of the pathogen decreased from 600 to 200 propagules/g soil, while in their absence it increased to 5·10 10 .
Increasing soil suppressiveness can be achieved by selecting certain crops. Thus, with the introduction of clover, oats, lupine, and potatoes into the crop rotation, the ratio between the causative agent of fusarium wilt of flax and the saprotrophic microflora of the soil increased from 1:14 to 1:44 - 1:70, which significantly increased the suppressiveness of the soil and reduced the death of flax seedlings by 30 40%. At the same time, the density of the pathogen population decreased by 3 times. In permanent flax crops, the biological balance between pathogenic and saprotrophic species in the soil is disrupted, as a result of which the share of the causative agent of fusarium wilt in the overall structure of mycoceiosis, which includes 34 species, increased to 90% in some years, which caused massive plant disease.
With water deficiency, tissue infection increased many times, inhibiting the healing process. In addition to soil, the pathogen persists in plant residues. Moreover, if infected crop residues are covered with a thin layer of soil, then the formation and dispersal of conidia does not occur. Additional transmission of the pathogen is also possible through seeds, and during the growing season - by airborne droplets using conidia. The importance of this transmission mechanism especially increases in protected ground.
The strategy for integrated plant protection against fusarium blight should include increasing soil suppressiveness and maintaining soil moisture at an optimal level for agricultural crops (at least 60% of full moisture capacity) to interrupt the mechanism of transmission of the pathogen through the soil, as well as the use of pathogen-free seeds for sowing. The cultivation of resistant varieties is of particular importance.
In order to improve soil health, black fallow is used in field crop rotations, as well as a 5-6-year break in the cultivation of susceptible crops. Systematic removal of infected plant debris is important. In protected soil, soil is disinfected at all stages of crop cultivation (disinfection of the main soil, peat mixtures for humus pots and bedding). It is effective to grow seedlings without picking in peat cubes, observe cultural rotation, enrich the rhizosphere of plants or substrate with antagonists, in particular Trichoderma viride, by pelleting seeds (400 g/c) and additionally adding the drug when planting seedlings in the ground and during the growing season (2.7 ·10 10 spores per 1 plant).
An excessively high content of species of the genus Trichoderma in the soils of greenhouse complexes often leads to inhibition of the development of other beneficial microflora and plants. It is recommended that the proportion of species of this genus in the structure of mycocenosis should not exceed 45%. In this case, pH values should be in the range of 4.5-7.5. In an alkaline environment (pH 8.5-9.0), Trichoderma practically does not develop.
Suppression of Fusarium wilt of cotton is achieved when the ratio between the pathogen and the introduced Trichoderma population is 1:8 and 1:10, provided that Trichoderma accounts for no more than 30-35% of all fungi.
Field experiments have shown the possibility of a biological method of combating the pathogen on tomatoes using antagonist bacteria Pseudomonas mycophaga (strain D-1). Before planting in the ground, tomato seedlings were treated by soaking the roots for 3.5 hours in a seven-day bacterial culture liquid (1:100 dilution) mixed with soil to a pasty consistency. On an area of 20 hectares, the incidence of Fusarium wilt decreased from 28.2 to 0.8%; At the same time, the fruit yield increased from 181 to 239 c/ha, and the return on the cost per ruble amounted to 16.6 rubles.
To avoid the transmission of pathogens through seeds, they are sorted, cleaned, calibrated and treated with TMTD or foundationazole.
The contamination of spring wheat and flax seeds after dressing should not exceed 5%.
To increase plant resistance to infection, it is recommended to avoid growing field crops on soils with low pH and high content nitrate nitrogen. Fertilizers should be applied in accordance with the data of agrochemical cartograms. In protected soil, it is important to maintain optimal conditions for growing cucumbers and tomatoes: soil moisture 85-90% of full moisture capacity, temperature 20-26°C (at night not lower than 18-20°C, during the day not higher than 30°C), watering with heated water (not higher than 25°C).
To prevent transmission of the pathogen by airborne droplets, crops are sprayed with foundationazole.
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Phytopathogenic fungi significantly reduce decorativeness, viability, as well as the yield and quality of food plant species, and fruit trees and berry fields, in addition, the terms of their economic use are also reduced.
Fungal spores can persist for a very long time in post-harvest residues, in the soil, and can be carried by wind, raindrops, animals and humans, containers, machines and tools. This is why it is so important to keep everything clean, and to always carefully and carefully dispose of plant debris on your site.
The presence of various fungi on plants is indicated by a change in the usual green color of the leaves and the characteristic color of the buds and flowers. It also manifests itself in the appearance of a cotton-like growth on the wood of soft or softened areas on the plant, spots of different colors or a gray “fluff” on the leaves, black sooty dots or dusty red “spots”, intersecting gray “threads” of fungal hyphae on the soil surface. On diseased fruits, rotten leaves and rotten wood, mushrooms may look like a loose “lace” or powdery mass, like a “film” or “crust”, or have the appearance of plates or scales. Under the influence of developing fungi, plant tissues become covered with plaque, spots or atypical “veins”. Then the parts of the plants affected by the fungi begin to die and decompose; or, conversely, curl, dry out, become deformed and become covered with cracks. The sooner diseased plants (or parts thereof) are identified, the simpler and easier it is to fight fungal diseases.
What can be done to, if not get rid of fungal diseases, then at least significantly reduce their likelihood. There is, for example, such a well-known agronomic technique as liming the soil. In this case, the soil is alkalized and thereby reduces the risk of damage to plants (for example, clubroot). If there is a lack of boron in the soil, beets are more likely to develop heart rot. Excessive application of nitrogen to the soil with a lack of phosphorus and potassium increases the damage to cereals by rust, and to potatoes by late blight.
At home, a liquid for disinfecting plants, pots and plant care equipment can be prepared from a solution copper sulfate with the addition of one of the available insecticides. To obtain a disinfectant liquid, 2 g of Actellik (or 1 g of Decis; or 1 g of Karate) is added to a 0.5% solution of copper sulfate (5 g per 1 liter of water). You can use an aqueous solution (0.1–0.2%) of potassium permanganate (potassium permanganate) for treating equipment and spring tillage.
Prolonged rains and high soil moisture, stagnant humid air in dense plantings often lead to fungal diseases garden plants. One preventative method is to keep the garden clean. You should regularly collect all the carrion, and at the first signs of damage by fungal diseases, immediately begin treating the diseased plants. Severely affected specimens that cannot be treated must be burned.
When propagating plants and caring for them they use charcoal and other means that prevent the penetration of pathogenic fungi into plant tissue. Biogrowth regulators, such as Energen, help strengthen plant immunity. Energen increases productivity by 30-40%, stimulates the growth and development of plants, protects against adverse factors, frost, drought, increases the survival rate of plants during transplantation, and also reduces the nitrate content in fruits.
If the plants still become sick, then you have to resort to treating them with suitable fungicides, or, in order to avoid rapid infection and death of many plants. especially in the collection, destroy diseased specimens.
Essential oil, in the form of spraying or treating plants with an alcohol solution of essential oil (1:100), has a powerful effect on the reproduction and spread of harmful fungi. Pronounced antifungal properties have essential oils oregano, thyme, monarda, lavender, patchouli, hyssop, marigold, eucalyptus, cedar and some other plants. You can use alcoholic extracts of plants such as onions, garlic, marigolds, yarrow, tansy as an antifungal agent, which are prepared in a proportion (1:10, and then, before use, also diluted in water 1:10).
Plant diseases caused by fungi
BLACK FOOT is the most common disease that affects seedlings of most crops. When young plants are infected with blackleg, white spots and constrictions form in the lower part of the stem, which subsequently turn brown and rot, causing the plants to wither and die.
ROOT ROT – often affects adult plants: they begin to lag in growth, turn yellow, and then partially or completely die. Species affected by root rot cannot be planted in the soil into which they were introduced. fresh manure, as well as in places where in previous years there were plants affected by this disease.
Fusarium wilt - brown necrotic spots appear on leaves and stems. The plant is stunted and then dies. Plants of the same species cannot be planted in their place for several years. In the germination phase, rotting of the roots, stem at the root collar and cotyledons is observed. The seedlings turn brown and often die before reaching the soil surface.
Powdery mildew - a white powdery coating appears on the lower and/or upper side of the leaves and petioles, and then dark spots.
PERONOSPORASIS or downy mildew is widespread in areas with sufficient moisture. The disease affects all above-ground organs. The disease manifests itself in two forms: general plant oppression (diffuse damage) and leaf spot (local damage).
RUST – widespread. The disease most often appears in the second half of the plant growing season. The disease develops most strongly in warm and humid years.
Fungicides are drugs used against fungal diseases
These drugs are divided into a number of groups: inorganic (preparations based on sulfur, copper and mercury) and organic. They are divided into preventive (they stop the development and spread of the pathogen at the site of accumulation) and therapeutic (they cause the death of the fungus after it infects the plant). Fungicides are also contact and systemic. Contact fungicides, when applied to plants, remain on the surface and cause the death of the pathogen upon contact with it. The effectiveness of contact preparations depends on the duration of action, the amount of fungicide, the degree of retention on the treated surface, photochemical and chemical resistance, weather, etc. Systemic fungicides penetrate into the plant, spread through the vascular system and suppress the development of the pathogen due to direct exposure to it or as a result metabolism in the plant. Their effectiveness is mainly determined by the speed of penetration into plant tissue and to a lesser extent depends on meteorological conditions. The nature of the use of fungicides is different: seed protectants, for treating soil and plants, both during the dormant period and during their growing season.
With the systematic use of the same fungicides, their effectiveness may decrease due to the formation of persistent races of the pathogen. To prevent this phenomenon, it is necessary to strictly adhere to the dosage of the drug and alternate fungicides.
Biological fungicides: Fitosporin, Barrier, Barrier, Fitop, Integral, Baktofit, Agat, Planzir, Trichodermin. Biological fungicides are characterized by low toxicity and high efficiency.
Acrobat M, Ditan M-45, Ridomil, Sandofan - have a systemic, penetrating and contact effect, acting against a wide range of phytopathogenic fungi.
Bordeaux mixture (one of the most effective and oldest remedies) is effective in the fight against rust, gray rot, spotting, late blight, scab and false powdery mildew. To spray plants during the growing season, use a 1% solution; to spray woody plants before buds open, use a 3-5% concentration.
Glyocladin - Analogue of Trichodermin. Biological fungicide to suppress pathogens of fungal diseases in the soil.
Potassium permanganate (potassium permanganate) is used to treat seeds, bulbs, corms, and plant rhizomes in a concentration of 0.1–0.15% for two hours. Can be used for health-improving watering of seedlings, seedlings and adult plants at the root in the fight against blackleg, fusarium, and bacteriosis. Used to disinfect equipment and tools.
Oxychome has contact and systemic activity. It has a destructive effect on pathogens at all stages. Provides a long-term therapeutic and preventive effect.
Soda ash (baking soda) is used to combat powdery mildew. For spraying, prepare a 0.3–0.5% solution. For better adhesion to plants, laundry soap is added to the soda solution.
Tattu enhances immune system plants, is well tolerated by plants throughout the growing season.
Tilt, Topaz, Skor, Bayleton, Alto, Impact, Vectra - have a systemic, penetrating and contact effect, acting against powdery mildew and rust fungi.
Trichodermin. Biological fungicide for the treatment and prevention of root infections of plants. The mycelium of the fungus, growing from spores in moist soil, suppresses about 60 types of soil pathogens that cause root rot.
Fitosporin-M is a microbiological preparation intended to protect plants from a complex of fungal and bacterial diseases.
Fundazol is a fungicide and disinfectant with a wide spectrum systemic action against large number fungal diseases of seeds and plants.
Copper oxychloride is effective against the same diseases as Bordeaux mixture. Used in 0.4–0.5% concentration. Do not add soap to the working solution.
When purchasing fungicides, they are always accompanied by instructions for use. It is very important to strictly follow the dilution instructions, use of recommended doses, timing and rules of application.
Alexey Antsiferov, candidate of agricultural sciences,
Corresponding Member of ANIRR
Pathogens most often penetrate the plant through the root system and subsequently cause its death. Inside vascular system An extensive branched mycelium develops, as a result of which the affected plant dies. Fusarium wilt develops very quickly, in fact occurring within a few days of infection.
The disease is common in all climatic zones. In our country, it is most often found in the south, southeast or Far Eastern regions. On average, in the most unfavorable years, productivity different cultures may decrease by 40%.
Fusarium wilt of cucumber early stage can be diagnosed by drooping top during hot hours. If the disease occurs in acute form, then the plant withers completely and instantly. It suffers - the main rhizome dies, but the lateral shoots partially remain viable.
It starts with a color change lower leaves. They become chlorotic and drooping. As the disease progresses, the color of the veins changes - they become brown. Gradually all the leaves begin to die, necrosis appears.
Fusarium wilt of strawberries begins with the death of tissue along the edges of the leaves and slight wilting. Then the petioles and leaves turn brown, and the rosette loses its elasticity and falls apart. Rot may appear when high humidity. The plant dies completely after about 1.5 months.
In general, it can be noted that Fusarium wilt can occur at any stage life cycle plants, but most often this occurs during the flowering period.
How does infection occur?
The main source of infection is contaminated soil. Therefore, plants most often suffer in greenhouses, where the soil is not changed and crop rotation is not applied. Another cause of fusarium is contaminated seeds. Fungi develop and grow together with the plant, and then destroy it.
Fusarium wilt: measures to prevent and control the disease
Etching planting material will prevent the possibility of introducing pathogens into the seed bed. Good digging of the soil, loosening, replacing the substrate, crop rotation and disinfection of tools also reduce the possibility of the disease occurring. Mushrooms develop well when high temperature air (about 28 ° C), high humidity and short daylight hours. Therefore, it is necessary to ventilate greenhouses well. As a preventive measure, you need to inspect the beds once a week and identify affected plants. Diseased specimens are removed and burned. Good results shows preliminary steaming of the soil and its disinfection with special biological preparations based on fungal antagonists. Among chemical preparations, you can use “Privekur”.
A third example is Fusarium culmorum, which also infects the roots of seedlings of a wide variety of plants (asparagus, cereals). It is not found in the soil as a free mycelium, unlike Pythium and Rhizoctonia, since its spores germinate only in the presence of a suitable substrate. All these species belong to saprophytic “sugar” mushrooms. They preferentially attack young, already damaged or weakened roots and never disappear from the soils of cultivated fields.
Fungi that damage vascular vessels are found primarily in the Fusarium oxysporum group and among the Verticitlium species. The fungi that cause tracheomycosis penetrate the roots of the host plant, in which they, however, immediately grow to the conducting vessels (xylem).
This leads to plant wilting, which does not occur as a result of mechanical blockage of blood vessels, but is caused by the action of fungal secretions on the plants.
Mushrooms primarily secrete special wilting toxins (fusaric acid, lycomarasmine), which disrupt the osmotic functions of living cells, mainly in leaves. Secondly, they contain pectinase, which destroys protopectin, the main substance of the middle plates in the vessels. The pectic acids and other partial hydrolysis products released in this way increase the viscosity of the xylem sap and thereby impede the water supply.
Since the remaining tissues of the host plant are resistant to wilting pathogens, only a few, less resistant vessels are affected. Only after the plant dies and the fungus leaves the conducting vessels can the affected root infect neighboring roots. Forcibly removing a damaged plant causes infected parts of the roots to remain in the soil, and the disease spreads even faster. The application of nitrogen fertilizers stimulates the development of fungi that attack blood vessels, directly enhancing their nutrition.
Since fungi can exist as saprophytes, they do not disappear even when crop rotations change. Tracheobacterioses are widespread, the causative agents of which can be, for example, Erwinia tracheiphila, Corynebacterium michiganense, Xanthomonas campestris or Pseudomonas solanacearum. These bacteria also contain pectinase and even cellulase, so the process of plant wilting occurs in the same way as when damaged by fungi.
However, all these fungi can remain for many years in the form of dormant spores (archymycetes, phycomycetes) or sclerotia (ascomycetes, imperfect fungi) in the absence of their host, until a suitable food plant appears again.
Low temperatures, drought and poor soil aeration allow mushrooms to better tolerate the cold season. Likewise, resting cabbage clubroot spores survive longest in relatively dry, alkaline soils. Such conditions limit the possibility of spontaneous germination of spores, which in winter would naturally damage the mushrooms.
If with tracheomycosis the growth of the fungus inside the plant does not depend on the condition of the soil, then for ectotrophic fungi developing in the roots, soil conditions are always decisive.
In addition, they damage only the seedlings, so the period of possible infection is relatively short. The opposite is true for Ophiobolus fungi. True, the processes in the soil are so complex that it is quite difficult to predict the impact of certain measures, such as applying fertilizers. With each new combination of external factors, conditions may develop completely differently.
Under the influence of pathogenic fungi, pathological processes occur in plants, accompanied by disruption of the structure and physiological functions of the plant or its individual parts, for example, the formation of growths, swellings, changes in respiration, assimilation, enzymatic activity, impaired growth and development, and death of affected tissues. Externally G. o. r. characterized by one or another type of lesion, which can be local or general. To local defeat, covering small areas plants or its individual organs, include spotting (cercospora (See Cercospora) of beets, apple and pear scab, etc.), fungal plaques (powdery mildew etc.), ulcers, pustules (plant rust); to the general - withering of plants.
G. b. r. transmitted by seeds, tubers, bulbs, roots, cuttings, seedlings and other parts of diseased plants. The infection can persist in post-harvest residues, in the soil, and be transmitted by wind, raindrops, animals and humans, containers, agricultural products. machines and tools. Pathogenic fungi can penetrate plant tissues through stomata (grape miles), water pores, lentils, through epidermal cells and cuticle (cabbage clubroot, potato canker), hail wounds (corn smut), sunburn, frostworm (black apple cancer), through cracks. Many insects, by damaging plants, open the “gate” of infection and often transmit pathogens.
Chemical measures consist of treating seeds with fungicides (see Fungicides), vegetative plants, disinfection of agricultural products. premises, storages, soil, etc.
Lit.: Naumov N.A., Diseases of agricultural plants, 2nd ed., M. - L., 1952; Natalina O. B., Diseases of berry growers, M., 1963: Dictionary-reference book of phytopathologist, ed. P. N. Golovina, 2nd ed., Leningrad, 1967: Tupenevich S. M., Shapiro I. D., Defense vegetable crops and potatoes from diseases and pests, 3rd ed., L., 1968.
S. M. Tupenevich.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what “Fungal plant diseases” are in other dictionaries:
fungal plant diseases- Table 25. Fungal diseases of fruit: 1 gray fruit rot of stone fruit (plum); 2 apple tree milky sheen; 3 the same, fruiting of a mushroom on the bark of a tree; 4 apple scab; 5 apple tree fruit rot and mummified... ...
Processes that occur in a plant under the influence of various causes of pathogens and unfavorable conditions environment, manifested in dysfunction (photosynthesis, respiration, synthesis of plastic and growth substances, water flow,... ...
Plant diseases are processes that occur in a plant under the influence of various causes of pathogens and unfavorable environmental conditions, manifested in dysfunction (photosynthesis, respiration, synthesis of plastic and growth substances, ... ... Wikipedia
See Plant Diseases... Agricultural dictionary-reference book
QUARANTINE PESTS AND PLANT DISEASES- naib, dangerous pests and diseases that are absent in the country or are common in part of its territory, but can be included in various categories. rns of the country or penetrate independently, spread and cause damage. X. cultures. Threat… …
Plant pests and diseases of quarantine significance for the USSR (1986)- I. Not registered in the USSR A. Plant pests 1. Orange scale + Unaspis citri 2. White-bordered beetle Pantomorus leucoloma 3. Great tangerine fly Tetradacus citri 4. Oriental mealybug Pseadococcus citriculus... ... Agriculture. Large encyclopedic dictionary
crop diseases- diseases of agricultural plants, pathological processes occurring in plants under the influence of pathogens and unfavorable environmental conditions; manifest themselves in disruption of photosynthesis, respiration and other functions, causing damage... ... Agriculture. Large encyclopedic dictionary
DISEASES OF AGRICULTURAL PLANTS- pathol. processes occurring in plants under the influence of pathogens and unfavorable environmental conditions; manifest themselves in disruption of photosynthesis, respiration and other functions, causing damage to the department. organs or premature death. B. s. r.... ... Agricultural encyclopedic dictionary
Diseases characterized by the formation of spots of dead cells on leaves, stems, fruits and other parts of plants; special case Nekrozov. Causes: lack of elements of soil nutrition for plants, pollution... ... Great Soviet Encyclopedia
Books
- Fungal diseases of strawberries and strawberries. Monograph, Govorova Galina Fedorovna, Govorov Dmitry Nikolaevich. The monograph summarizes domestic and foreign experience; the authors present the results of their own long-term studies of diseases and selection characteristics wild strawberries and strawberries...
