Peculiarities of the pathogenesis of septoriosis of spring wheat in the conditions of the Eastern part of the Forest-Steppe of Ukraine

Abstract

In recent years, spring wheat crops have been seriously harmed by foliar diseases, as evidenced by studies conducted by well-known scientists of Ukraine. In the phytopathogenic complex of spring wheat, pathogens of fungal etiology prevailed. The most common pathogen is Septoria tritici Desm. (teliomorph Mycosphaerella graminicola (Fuckel/J. Schrot). The article presents the results of a study on the study of bioecological features of septoriosis development of spring wheat Septoria tritici Desm. When the plants were affected by the causative agent of septoriosis, spots of an elongated rectangular shape, straw-colored, oily in appearance were formed due to the numerous formation of pycnidia. In septoriosis, the primary inoculum was sumcospores, which were formed in perithecia on plant remains. With high air humidity, ascospores were released and spread by wind and rain, affecting young plants. The secondary source of infection was infected plants on which conidial sporulation was formed. Pycnospores were formed inside the pycnidia, and under favorable conditions, the pathogen produced 6 to 12 generations per growing season. The optimal air temperature for septoriosis is 20–23 0С and the average daily air humidity is 66–80 %. We established that the pycnospores of the pathogen germinated on the leaves in 10–15 hours. The incubation period was 6–10 days. The causative agent S. tritici contained 15-18 thousand pycnospores in one pycnid. We have proven that the prevalence of the disease in the spring wheat variety Kharkivska 30 in the tillering phase was 14.8–15.2 %, during development it was 6.2–6.7 %. In the phase of emergence into the tube, the prevalence of the disease was 33.7–34.9 % with a degree of development of 10.2–13.3 %. In the phase of milk-wax maturity, the prevalence of septoriosis was 55.6–57.4 %, and the development of the disease was 22.7–24.1 %. Knowledge of the bioecological features of the development of the disease provides an opportunity for planning and effective implementation of protective measures to limit the spread and development of septoriosis of wheat. Carrying out systematic monitoring and diagnosis of diseases is of crucial importance in the development and improvement of spring wheat protection technology and control of phytopathogens. To protect spring wheat from septoriosis, a comprehensive approach is required with the use of breeding and genetic, agrotechnical, biological and chemical measures, taking into account the forecast of the development of the disease in a specific region of crop cultivation.