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13AGRICULTURAL SCIENCES
SORGHUM DISEASES IN POLISSIA OF UKRAINE
Stoliar S.,
Candidate of Agricultural Sciences Kliuchevych M.
Doctor of Agricultural Sciences, Professor Polissia National University Zhytomyr, Ukraine
ABSTRACT
The phytosanitary condition of Sorghum bicolor and Sorghum saccharatum phytocenoses during 2018-2021 was determined by conducting route surveys. It was found that the most common and harmful pathogens of fungal diseases of sorghum: Helminthosporium turcicum (Luttr.) K.J. Leonard & Suggs,Alternaria alternata (Fr.) Keissl., Magnaporthe grisea (T. T. Hebert) M. E. Barr, fungi of the genus Fusarium sp., Bipolaris sp., Rhizoctonia sp., Cercospora sorghi Ellis & Everh., Ascochyta sorghi Sacc. and bacterial: Pseudomonas syringae pv. syringae, Xanthomonas vasicola pv. holcicola, Robbsia andropogonis. It is investigated that the maximum development of pathogens reached at the end of the growing season at the 71st stage of development (phase of milk-wax ripeness of grain). Due to the peculiarities and biology of the potential of dangerous pathogens that lead to the development and development of its quality, it is important in the cultivation of crops and improve measures for their development.
Keywords: Sorghum bicolor, Sorghum saccharatum, mycoses, bacterial diseases.
Introduction.
Modern climate transformations are forcing agricultural producers to reconsider concepts and practical approaches to the formation of a range of crops of ag-rocenoses, able to ensure stable and cost-effective crops in increasingly stringent hydrothermal factors [1, 2, 3].
Under the current conditions of agricultural production in Ukraine, the prospect of realizing the agrobiological and production potential of sorghum crops, their introduction, production, consumption and use is extremely important. Among the botanical species that make up this group of crops, a special place should be given to grain sorghum (Sorghum bicolor L.) and sugar (Sorghum saccharatum (L.) Moench.), which are more typical of Polissia Ukraine, which are able to form sustainable and economically viable crops. grains with quality indicators that allow their multi-vector use [2, 3, 4].
In our opinion, the most important argument for more intensive involvement of Polissia sorghum in ag-rocenoses is its extremely high ecological plasticity, which can be a full-fledged alternative to other spring crops (barley, corn, sunflower) during unfavorable hydrothermal coefficients.
High-quality sorghum grain is used for the production of flour, cereals, bread, alcohol, starch, etc. Due to the high content of proteins and carbohydrates in the grain, sorghum is a valuable nutritious cereal. Thus, in grain up to 15 % protein and up to 80 % MEV, fats from 3.4 to 4.4 %, fiber up to 4.8 %, within 1.2-3.3 % ash, as well as keratin, B vitamins , riboflavin and tannins [2, 5, 7, 9].
Thus, perhaps the only deterrent to increasing grain and sugar sorghum production today, we see the lack of development of elements of zonal technology of its cultivation, as a result of increasing the spread and harmfulness of pathogens that inhibit the maximum
productivity of varieties and hybrids. Therefore, farmers need to pay special attention to the monitoring of pests in phytocenoses of culture, which are one of the main limiting factors in reducing yields.
Therefore, the aim of our research was to study the species composition of sorghum pathogens in Polissia, Ukraine, which will be reflected in improving the system of crop protection against harmful microorganisms and obtaining high quality phytoproducts.
Materials and methods.
The study of species of sorghum pathogens in Polissia Ukraine was carried out during 2018-2021 by conducting field surveys in the educational and research field of Polissia National University and PE "Tchaikivka" Radomyshl district of Zhytomyr region.
Accounting and observation of the spread of pathogens in phytocenoses was carried out according to the generally accepted method of phytopathological research: systematic visual inspections, the method of sampling of plants and accounting sites [11].
The meteorological conditions of the research period were characterized by unstable humidity: prolonged rains were replaced by long periods of drought, and air temperatures repeatedly exceeded the long-term norm. Note that sorghum is a drought-resistant crop, so abnormal weather conditions did not have a significant impact on the level of yield, but affected the spread of phytophagous.
Statistical processing of the obtained experimental data was performed by conventional methods using applied computer programs.
Results. Under modern conditions, an important reserve for increasing production and improving the quality of phytoproducts is to reduce sorghum crop losses by limiting the spread of phytocenoses in the culture of pests, especially pathogens of various etiologies [6, 8].
Phytopathogenic microorganisms cause significant economic damage to agriculture. Pathogens constantly infect seeds and all plant organs during the growing season. Pathogens, penetrating plants, disrupted physiological and biochemical processes and caused stunted growth, reduced assimilation surface, spotting, premature drying of leaves, impaired root development, plaques, rot, which led to a significant reduction in yield and deterioration. In plants affected by phytopathogens, grain quality deteriorates and yields
Monitoring of the phytosanitary condition of sorghum phytocenoses showed that during 2018-2021 the most common pathogens were fungal diseases: Helminthosporium turcicum (Luttr.) K.J. Leonard & Suggs, Alternaria alternata (Fr.) Keissl., Magnaporthe grisea (T. T. Hebert) M. E. Barr, fungi of the genus Fusarium sp., Bipolaris sp., Rhizoctonia sp., Cercospora sorghi Ellis & Everh., Ascochyta sorghi Sacc. and bacterial: Pseudomonas syringae pv. syringae, Xanthomonas va-sicola pv. holcicola, Robbsia andropogonis (Fig. 1,
decrease [10, 12].
Fig. 2).
Helminthosporium turcicum 29,6 %
Ascochyta sorghi, 8,6 %
Cercospora sorghi. 10,1 %
Alternaria alternata, 12,4 %o
Rhizoctonia sp 4,2 %
Magnaporthe grisea, 22,3 %
Fusarium sp., 5,5 %
Bipolaris sp.,
7,7 %
Fig. 1. The structure ofpathogens offungal diseases of sorghum in Polissia of Ukraine, 2018-2021
It was studied that the main share in the structure of pathogens of fungal diseases of sorghum in Polissia were: Helminthosporium turcicum (29.6 %), Magnaporthe grisea (22.3 %) and Alternaria alternata (12.4 %). Other pathogens Cercospora sorghi, Ascochyta sorghi, fungi of the genus Bipolaris sp., Fusarium sp., Rhizoctonia sp. - 10.1, 8.6, 7.7, 5.5, 4.2 % respectively.
The first manifestations of Helminthosporium tur-cicum appeared in the phase of 2-3 leaves (light green spots were observed, which gradually turned brown). The disease developed intensively on the leaves of adult plants in the form of elongated, elliptical, brownish spots with a border. In wet weather, the spots formed a gray-brown plaque, the leaves gradually withered and died. The affected grain was formed thin with blackening of the germinal end of the seed and reduced germination.
Magnaporthe grisea develops over a wide range of temperatures (15-35 °C) and humidity (77-82 %). The first symptoms of plant damage were observed at the 29th stage of development on the BBCH scale. Small (1-2 mm) light brown spots with a pronounced brown border appeared on the leaves. Over the next 1012 days, the spots increased in size and reached 10 cm. They had a rounded or elliptical shape and necrotized inside, which led to premature drying and death of leaves
Symptoms of Alternaria alternata have been reported in all years of research. The disease was detected in the ripening phase of the grain. Dark spots were formed on the scales, and during the grain ripening the embryo turned black. The formed grain affected by the pathogen was almost indistinguishable from the healthy one: large in size, well filled. However, the affected seeds had physiological abnormalities, namely: low germination energy and germination.
Fig. 2. The structure of pathogens of bacterial diseases of sorghum in Polissia of Ukraine, 2018-2021
Pseudomonas syringae pv. syringae, 43,5 %
Xanthomona s vasicola
pv. holcicola, 31,3 %
Robbsia andropogonis, 25,2 %
Sorghum was affected by phytopathogenic bacteria in all years of research. The most common signs of phytopathogenic bacteria were leaf spots and less often stems. The first symptoms of phytopathogenic bacteria were observed in July.
Pseudomonas syringae pv. syringae is dominant in the structure of pathogens of sorghum bacterial diseases. 43.5 %, andXanthomonas vasicola pv. holcicola and Robbsia andropogonis were 31.3 and 25.2 % respectively.
The first signs of damage by the pathogen Pseudomonas syringae pv. syringae is the appearance of water-saturated spots on the leaves. Eventually, they dry out and turn brown (from beige to dark brown). The spots had a characteristic red border, the color of which differs in different varieties of sorghum.
In favorable for the development of Xanthomonas vasicola pv. holcicola pathogen can affect up to 60 % of plants, with losses of green mass reaching 25 %. The first symptoms of the lesion were observed in July. Initially, water-saturated streaks appeared along the leaf blade. Gradually the strips necrotize and acquire a brownish-red color. With the strong development of the disease, the bands could expand, covering most of the surface of the leaves. Subsequently, the fabric dried and the leaf cracked. The maximum development of the pathogen was observed in the phase of milk-wax ripeness.
A characteristic feature of Robbsia andropogonis is the appearance on the leaves and stems of sorghum of red stripes ranging in size from a few millimeters to several centimeters. Over time, under favorable conditions for the development of the pathogen, the size of the bands increased. The stripes of Robbsia andropogonis may be light brown to dark purple (the color is determined by the sorghum variety), but they never have a border that is characteristic of P. syringae pv. syrin-gae.
Conclusion. Thus, modern climate transformations are forcing agricultural producers to reconsider concepts and practical approaches to the formation of a
range of phytocenosis crops capable of ensuring stable and cost-effective crops in increasingly stringent hydrothermal conditions.
Knowledge of the species composition of sorghum pathogens, as well as the peculiarities of their development and biology is key to establishing effective measures to limit their spread and development.
Our further research will be aimed at improving the conservation system of sorghum, which will be based on a rational combination of organizational and economic, agronomic, immunological, biological and other methods, taking into account ESP and technology of cultivation.
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