Pathogens Of Agricultural Crops Research Articles

Forecasting the phytosanitary state of agrocenoses: innovation developments

Goal. Development and implementation of new theories, methods, technologies and models that would allow more reliable forecasting of the development of pests and pathogens of agricultural crops.
 Methods. Analysis of innovative development of the Institute of Plant Protection of the National Academy of Agrarian Sciences of Ukraine and other institutions of the Scientific and Methodological Center «Protection of Plants» for 2001—2020. Isolation of those relating to the problem forecasting the development of pests and pathogens of plant diseases in agrocenoses of Ukraine.
 Results. The concept of formation of the phytosanitary state of crops and plantations under the conditions of climate change has been developed. The theory of the dynamics of the number of locusts and the prediction of emergency situations in the agricultural sphere of Ukraine has been developed. The widespread use of pheromone traps for diagnosing the phytosanitary state of agrocenoses of Ukraine is recommended. The cyclicity of outbreaks of mass reproduction of the Anisoplia austriaca beetle and the European corn borer was established, depending on the amount of solar activity. The possibility of applying GIS-technologies for the analysis of long-term data was studied. Predictive computer programs (models) of harvest shortages of rapeseed, sunflower, corn, sugar beet, and winter wheat from a complex of pests have been developed. An algorithm for the application of information technology programs for the analysis of multi-year dynamics of the phytosanitary state of agrocenoses has been developed. The role of the developed computer model of the development of leaf spots of grain crops in determining the moment for the most effective application of fungicides has been established. Methods of forecasting the development of pathogens of grape diseases in the South of Ukraine have been developed. A system of forecasting the phytosanitary state of agrocenoses of Ukraine in the conditions of the year and planning the implementation of protective measures has been developed.
 Conclusions. Innovative developments of the Scientific and Methodological Center «Plant Protection» make it possible to solve the following issues at a modern level: forecasting changes in the agrosphere based on the analysis of a long-term database of hydrothermal conditions and indicators of the phytosanitary state of agrocenoses; prevention of emergency situations in the agricultural sector on the basis of a modern monitoring system using GPS-navigation and the development of regulations for carrying out protective measures; forecasting the development of dangerous pests and diseases of agricultural crops; forecasting crop failures and determining the economic feasibility of chemical plant protection; forecasting the appearance and spread of quarantine pests.

Influence of tillage methods on the development of wheat diseases Aestivum and Fontum

Aim. To analyze the data in the available literature regarding the effect of various tillages on the development and prevalence of wheat pathogens.Discussion. According to the literature, the existing tillage technologies – classical, minimal and zero – significantly affect the development of pathogens that cause the development of wheat diseases in regions that differ in soil and climatic conditions. In Russia and other countries near and far, the issue of combating diseases of agricultural crops is dealt with by chemical, biological and agrotechnical methods. Despite the fact that agrotechnical methods are of the utmost importance in the general system of measures to protect plants from damage, for a long‐time agricultural technology as a means of plant protection was underestimated. However, many agricultural techniques, as well as genetics and selection, increase the resistance of plants to damage.Conclusion. As a result of these techniques, it is possible to create environmental conditions that will be unfavourable for the reproduction of diseases. At the present time, opinion is firmly established that separately undertaken, isolated methods cannot properly solve the problem of protecting plants from pathogens of agricultural crops. Only a set of methods combined into a system of measures provides a solid basis for plant protection. And in this system of measures, the role of agricultural practices is extremely large.

PAENIBACILLUS POLYMYXA КВ — PRODUCER OF BIOLOGICALLY ACTIVE SUBSTANCES

Objective. To investigate the ability of Paenibacillus polymyxa KB to produce biologically active substances that stimulate the growth and development of plants. Methods. Qualitative and quantitative determination of auxins, abscisic acid (ABA) and cytokinins in the culture fluid (CF) of P. polymyxa KB was carried out by high-performance liquid chromatography (HPLC) using Agilent 1200 liquid chromatograph; gibberellins were measured by high-performance liquid chromatography (HPLC/MS) using Agilent 1200 liquid chromatograph (Agilent Technologies, USA) and Agilent G1956B mass spectral detector. The content of vitamins in P. polymyxa KB was determined using Waters liquid chromatograph with a tqs-micro mass-selective detector. The content of amino acids in CF was studied by ion exchange chromatography on a Sycam amino acid analyser. The ability of P. polymyxa KB to synthesize exopolysaccharides and enzymes was determined using classical microbiological and biochemical research methods. Antifungal properties of the bacterium were studied by the dual culture method. Statistical calculations were carried out using analysis-of-variance method. Results. P. polymyxa KB synthesises phytohormonal compounds: auxins — up to 81.15 μg/g of dry biomass, abscisic acid — up to 9.84 μg/g; gibberellic acids (GA3 — within 2.48 μg/g and GA4 — 1.96 μg/g of dry biomass); cytokinins (zeatin — up to 16.42 μg/g, kinetin — up to 6.78 μg/g, isopentenyl-adenine — up to 9.03 μg/g of dry biomass), as well as vitamins: thiamine (B1) — within 0.93 mg/dm3 CF, riboflavin (B2) — 0.48 mg/dm3, pyridoxine (B6) — 0.27 mg/dm3, folic acid (B9) — 0.18 mg/dm3 CF. P. polymyxa KB shows phosphatase, amylolytic, proteolytic, pectolytic activity, produces amino acids: histidine — within 300.4 mg/dm3, alanine — 236.3 mg/dm3, proline — 164.2 mg/dm3, valine — 157.8 mg/dm3, isoleucine — 148.4 mg/dm3, threonine — 126.2 mg/dm3, cystine — 124.0 mg/dm3 CF and others. The bacterium synthesizes exopolysaccharides amylopectin and levan. P. polymyxa KB shows antagonistic activity against phytopathogenic micromycetes from the genera Fusarium, Alternaria, Nigrospora — pathogens of agricultural crops. Conclusion. P. polymyxa KB synthesizes a significant amount of physiologically active substances that can play an important role in the processes of plant organogenesis.

Development of Energy-Resource-Saving Plants for Disinfection of Soil and Substrate

The soil is a favorable environment for many microorganisms, pathogenic bacteria, fungal spores, insect eggs due to the presence of nutrients and moisture in it. Soil treatment from pests and pathogens of agricultural crops for the purpose of disinfection can be carried out by chemical, energy, thermal and biological methods. The most common method is thermal. The article proposes to use infrared heating as an alternative energy source. (Research purpose) The research purpose is developing energy-resource- saving installations for disinfection of soil and substrate. (Materials and methods) The article presents three devices and their capabilities for disinfection of soil and substrate with infrared radiation. (Results and discussion) One of the options for progressive scientific and technical developments is the development of software management of soil and substrate disinfection for the implementation of energy-saving electrical technologies, which regulates parameters depending on the set values: heating time, height of the frame with IR burners above the ground, humidity, porosity, soil temperature, ambient temperature and power of infrared burners. (Conclusions) During the analysis of the state and prospects for the tillage before planting, the need for the development of scientifically based devices for disinfection of soil and substrate was justified. The proposed use of software control of soil and substrate disinfection will allow setting and maintaining the required level of treatment depending on the technological process, type of soil, open or closed ground. The use of an automatic disinfection control system will make it possible to achieve optimal processing parameters and increase productive indicators.

Подбор консорциумов на основе эффективных штаммов гриба рода Trichoderma для создания биофунгицида

As an agrarian country, Kazakhstan has sufficient resources to produce high quality organic products which are in demand in foreign markets and can be sold at higher price in comparison with inorganic analogue. The use of biological plant protection measures will improve the quality of produced organic products, as well as will positively effect on soil recovery. Fungi of the genus Trichoderma are effective antagonists of many fungal pathogens of crops and natural alternative of chemical fungicides, characterized by rapid growth on cheap nutrient media. Studies all over the world show that consortia consisting of several microbial species or strains are more effective as a biological plant protection measure than preparations comprising a single microbial species or strain. Thus, the possibility of cultivating three different Trichoderma strains without inhabiting the growth and development of each individual strain as part of a separate consortium was studied by the method of counter cultures. As a result of the studies performed, three most compatible consortia numbered 2, 3 and 4 were selected, without noticeable suppression of the growth of each strain. Studies have also shown abundant growth and sporulation of Trichoderma strains on organic nutrient media based on bran and oat flour, rather than on synthetic Czapek-Dox medium. The selected consortia will be used in further research to identify their antagonistic properties in relation to various pathogens of agricultural crops. Moreover, the most optimal conditions will be determined, providing many conidia with a long shelf life.

Chitinase production by Trichoderma viride in submerged state fermentation

We have identified the optimal conditions for the production of chitinolytic enzymes of T.viride in submerged state fermentation. The production of chitinase by a new strain of fungus was carried out on the basal liquid medium, containing (%) colloidal chitin 0.5, NaNO3 0.2, KH2PO4 0.1; MgSO44-7H2O 0.05 and KCl, 0.05. The activity of enzymes of the chitinase complex of the strain was evaluated using the method using dinitrosalicylic acid (DNS reagent). A quantitative determination of the activity of chitinases in a producer microorganism was established by their ability to hydrolyze 0.2% colloidal chitin (in phosphate buffer 0.05 M, pH 5.2), by the content of reducing sugars formed in this process, which were evaluated using a DNS reagent. The results of studies of the influence of various cultivation parameters showed that highest chitinolotic enzymes production by T.viride was obtained at pH 4.0, (301.15-303.15) K and after 144 h growth. The studied soil isolate can be further used in biotechnological research, as well as for biological control of pests and pathogens of agricultural crops.

Soil Disinfection Methods in Protected Ground

Soil is a favorable environment for many microorganisms, pathogenic bacteria, fungal spores, insect eggs due to the presence of nutrients and moisture in it. Soil treatment from pests and pathogens of agricultural crops for disinfection can be carried out by chemical, energy, thermal, biological methods. The most common method is thermal. This is because many pests and pathogens have a protein structure that is easily destroyed when the temperature increases, and the thermal effect can be obtained from various heat carriers. (Research purpose) The research purpose is in developing an energy-efficient method of soil disinfection using infrared radiation. (Materials and methods) The article shows the relation between the spectral thermoradiation characteristics of soil with characteristics of infrared emitters, namely the amount of applied heat, temperature, conductivity, soil moisture, and exposure time, to justify the rational mode of operation for decontamination of the soil. The article presents a mathematical model for this purpose based on known laws that determine the relationship between the necessary parameters. (Results and discussion) Authors offered a plant for soil disinfection with infrared radiation. It was found that the high energy efficiency of the installation is achieved by a high efficiency of infrared burners and infrared radiation affects directly the object of treatment, the soil. The article presents structural-logical and mathematical models of infrared power supply. (Conclusions) Analysis of the heating kinetics equation showed that the maximum permissible speeds for the process of infrared heating of the soil depend on its thermophysical properties, the maximum permissible temperature, the area and the required depth of warming of the soil. It was found that infrared heating and a device for disinfecting the soil in this way will allow energy-efficient, convenient and fast processing.

Genómica de hongos fitopatógenos como herramienta para el desarrollo de estrategias de manejo

Los patógenos más devastadores de los cultivos agrícolas son los hongos, su manejo ha variado en el tiempo, este se ha dado de acuerdo al desarrollo del conocimiento de cada época y a la cultura. En las últimas dos décadas el desarrollo vertiginoso de las plataformas de secuenciación masiva y la bioinformática ha permitido la generación cientos de secuencias de genomas completos de hongos incluidos los fitopatógenos, abriendo la puerta para mejorar estrategias de manejo existentes y generar nuevas.Los hongos son considerados los patógenos más devastadores de las plantas causando el 60% de las pérdidas, a pesar de que solo el 10% de los hasta ahora descritos puede colonizar plantas vivas (Aslam et al., 2017); es decir, solo un pequeño número es considerado patógeno de especies vegetales. El manejo de enfermedades causadas por estos, en cultivos de importancia económica, siempre ha sido un reto que afrontar por el hombre desde la aparición misma de la agricultura. Las estrategias se han dado de acuerdo al desarrollo del conocimiento de cada época y a la cultura. Los primeros reportes escritos de enfermedades son mencionados en algunos textos griegos antiguos de Homero (1000 años a.C.); también aparecen en el antiguo testamento (750 años a.C.) y fueron documentadas de manera similar a como se abordaron las guerras y las enfermedades humanas. Los primeros agentes causales a los que se les atribuyeron las pérdidas de los cultivos fueron las divinidades a manera de castigo, y el manejo se daba a través de ofrecimiento de sacrificios a los dioses para que se apaciguaran y de esta forma evitar el daño de los cultivos a causa de mildeos, royas entre otras plagas. También los textos de Homero señalan la posibilidad de manejarlas con el uso del azufre, y Demócrito (470 años a.C.) recomendaba el uso de aceite de oliva para contrarrestar los tizones (Agrios, 2005).

De novo genome assembly of Geosmithia morbida, the causal agent of thousand cankers disease.

Geosmithia morbida is a filamentous ascomycete that causes thousand cankers disease in the eastern black walnut tree. This pathogen is commonly found in the western U.S.; however, recently the disease was also detected in several eastern states where the black walnut lumber industry is concentrated. G. morbida is one of two known phytopathogens within the genus Geosmithia, and it is vectored into the host tree via the walnut twig beetle. We present the first de novo draft genome of G. morbida. It is 26.5 Mbp in length and contains less than 1% repetitive elements. The genome possesses an estimated 6,273 genes, 277 of which are predicted to encode proteins with unknown functions. Approximately 31.5% of the proteins in G. morbida are homologous to proteins involved in pathogenicity, and 5.6% of the proteins contain signal peptides that indicate these proteins are secreted. Several studies have investigated the evolution of pathogenicity in pathogens of agricultural crops; forest fungal pathogens are often neglected because research efforts are focused on food crops. G. morbida is one of the few tree phytopathogens to be sequenced, assembled and annotated. The first draft genome of G. morbida serves as a valuable tool for comprehending the underlying molecular and evolutionary mechanisms behind pathogenesis within the Geosmithia genus.

Composted recycled organic matter suppresses soil-borne diseases of field crops.

• Suppression of soil-borne diseases of horticultural crops by composts has been attributed to the activities of antagonistic microorganisms. The potential for abiotic disease suppression in field-grown crops was explored using glasshouse-based bio-assays for five pathogens of agricultural crops and eight formulations of recycled organic matter compost. • The effects of compost formulation and postmaturation processing were investigated by comparing disease severity on recycled organic matter composts with a commercial seedling compost. Comparisons were made within native and autoclaved series of composts. Autoclaving perturbed compost chemistry without the addition of other materials. • The severity of autoclaving-induced changes to compost chemistry were related to formulation and processing issues. Extractable carbon content, nitrate-N content and pH all contributed to the suppressive capacity of recycled organic matter composts. There may also be a biotic component to the suppression observed. • For each pathogen the influential chemical characteristics of suppressive composts were the same as those identified for soils in other studies. There is potential for the suppressive capacity of recycled organic matter composts to be improved.