Abstract
Purpose. To detect harmful organisms on spring barley and their variability under the influence of hydrothermal conditions during the crop vegetation period in the Eastern Forest-Steppe of Ukraine and to improve methods of pathogen detecting on plants and grains.Material and methods. The prevalence of diseases and pests was determined by conventional and special methods in accordance with the existing assessment scales and by methods modified by us in the course of work. We improved methods for determining pathogenic species on spring barley upon spring (optimal) and autumn (simulation of wet conditions) sowing followed by evaluating the disease signs during the tillering phase of plants and selecting nutrient medium for phytoexamination of grain and assessment of its infection rate.Results and discussion. The 2009–2020 assessments of the prevalence of diseases and pests on spring barley plants from seeds sown on different dates (autumn and spring) showed that the autumn sowing was more effective for barley net blotch manifestation on spring barley compared to the conventional method of spring sowing, since the autumn conditions are favorable for development of this fungus. Pathogens on spring barley were mainly represented by head smut (Ustilago hordei), barley leaf stripe disease, root rots and corn flies. The greatest prevalence of head smut (up to 67.0%) was observed in the years when the weather was excessively humid during the growing period (HTC =1.7 in 2020) or slightly arid (HTC =1.1 in 2015). The greatest spread of barley net blotch (100%) was observed on sufficient water supply in 2014 (HTC = 1.4). The numbers of frit flies during the study period were significant (up to 100%), only in 2016 there was a decline to 39%. The pathogen species that develop on spring barley seeds were determined. Alternaria contamination of grain ranged 9.0 to 77.0% from year to year; Drechslera contamination - 4.0 to 55.0%, Fusarium contamination - 0.0 to 12.4%.Conclusions. Head smut (Ustilago hordei (Pers. Lagerh.)) and Drechslera fungi causing leaf blotch and root rot (Drechslera teres Ito, D. graminea (Rabenh.) Shoemaker, D. sorokiniana Subram) were found to be the most common diseases of spring barley in the Eastern Forest-Steppe of Ukraine. Of pests, frit flies (Oscinella frit Linnaeus and O. pusilla Meigen) were most common. Major diseases of spring barley seeds are of fungal etiology (genera Drechslera spp., Fusarium Link. and Altenararia Fries). Two new methods of phytopathological analysis of the prevalence of diseases on spring barley crops have been developed: one of them is carried out by autumn sowing of seeds and evaluating plant damage during the tillering phase; the second method is phytoexamination of seeds for pathogens via germination of caryopses in sucrose solution
Highlights
Spring barley is a leading food crop at the world market, ranking fourth among cereals in terms of sown area [1]
To improve the methods of determining the species of harmful organisms on spring barley, seeds were sown in two seasons: in spring and autumn with subsequent measurement of the affection of plants by pathogens causing leaf and root diseases as well as by intrastem pests during the tillering phase
To determine the fungal contamination of barley grain, we developed the method, which consists in caryopsis germination in sucrose solution in a humid chamber under constant light, accelerating the manifestation of disease signs on infected grain
Summary
Spring barley is a leading food crop at the world market, ranking fourth among cereals in terms of sown area [1]. Spring barley is suitable for growing in all climatic zones of Ukraine and, provided intensive technologies, gives a grain yield of 5–8 t/ha [2]. Among the factors limiting the barley grain yield and quality in the country, there is farmers‟ inattention to protection of crops against harmful organisms. This is primarily attributed to the inadequate awareness of farmers about changes occurring in spring barley agrocenoses because of simultaneous impact of anthropogenic activities and weather conditions. In Ukraine, the climate tends to change: there are sharp fluctuations in precipitation periods and a significant increase in temperature in most regions of the country [5]. Climate changes affect the plant vegetation length, and the dynamics of harmful organism development on agricultural crops, including spring barley
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