Distribution of species of Fusarium and Alternaria genera on cereals in Ukraine

Abstract

In recent years phytosanitary situation in agrophytocenooses has worsened, and damage caused by diseases increased. In the conditions of field experiments in the vegetative seasons of 2015–2018 the dissemination of Fusarium and Alternaria spp., and composition of Fusarium species in Ukraine were studied. The selection of plant samples was carried out twice – at the beginning of vegetation and before entering into wintering. In autumn the samples of winter wheat with the symptoms of root rot from more than 150 fields from different oblasts of Ukraine were selected. Later these samples were analyzed using PCR method in real time to determine the species composition of Fusarium genus. In the analysis of grain material from different regions of Ukraine we determined high level of Fusarium infection. Fusariosis of grain were observed in several areas in more than 50% of samples from all regions of county. In all oblasts of Ukraine, the high level of Alternarìa infection were identified also. It is found out that the main sources of the root rot are F. tricinctum, F. graminearum, F. poae and F. avenaceum. The role of F. avenaceum, as the pathogen of root rot was at the level of F. graminearum and F. sporotrichioides in most regions of Ukraine. The studies reveiled that the dominant species in the grain material were F. tricinctum and F. graminearum, presence of which exceeded 20–25%. Quite often F. poae and F. sporotrichioides was observed, presence of which in grain equaled 15–20%. In the Central, Eastern and Southern regions, the dominant species was F. avenaceum with a level of identification 15–23%. F. culmorum, F. langsethiae were within 5–7%. The species composition of fusariosis in the grain and the species composition of pathogens that cause fusariosis root rot in general are similar. Fusariosis becomes one of the most common and harmful diseases of grain crops, and cause no less harm than smut diseases. The fact that their danger continues to grow is explained by adverse weather conditions (alternation of wet and arid periods) and reduction of general level of cultivation: distribution of corn fields, decrease of expenses on tillage, and low-quality pesticides, often generics. It should be noted that the best precursors for cereal crops, for example, soy bean, is also vulnerable to fusariosis. Therefore, performing protective measures at preparing of grain for sowing and in the period of vegetation of the crop will contribute to total reduction of the levels of infection of agrophytocenoses with Fusarium species and potential damage to the cultivated plants. The study revealed that species of fungi belonging to the Alternaria and Fusarium genera infect wheat grain in the yields of each year. The results of data analysis of the genera showed antagonistic interaction between them. Perhaps, particularly at such negative interaction in the vegetative season of 2018, during, practically continuous warm rains in the "grain belt" of Ukraine during the generative period of development of wheat, the grain was infected with Alternaria spp. at moderate presence of Fusarium species. These patterns in the interaction of Alternaria and Fusarium spp. are expedient to be taken into account during development of systems of control of fusariosis using fungicides. Absence of contamination of grains with mycotoxins of Fusarium species does not reduce the levels of danger for crops posed by probable increase in the levels of presence of Alternaria mycotoxins – alternariol, alternariol monomethyl ether, tenuazonic acid, etc. Certainly, the results of the vegetation season of 2018 year and the large-scale alternariosis infication require clarifications to the current normative documentation. The conducted researches are important for improvement of protection systems for crops in intensive technologies of cultivation.