Abstract
Septoria tritici blotch is one of the harmful diseases of wheat cultivars cultivated in the Russian Federation and the Republic of Kazakhstan. The purpose of the research was to study a sample of Zymoseptoria tritici isolates obtained from the Saratov and Tambov (Russian Federation) and Almaty (Republic of Kazakhstan) regions according to the degree of the azoxystrobin sensitivity, as well as to evaluate these isolates for the presence of the G143A mutation using PCR-RFLP analysis. The azoxystrobin sensitivity of Z. tritici isolates was evaluated by studying the growth restriction of cultures on a nutrient medium (concentrations of active drug in the medium were 100, 10, 1, 0.1, 0.01 mg/l.). In the control, on the 21st day of cultivation, the diameter of the colonies of Z. tritici strains varied from 14.24±1.43 mm to 19.53±0.66 mm. Azoxystrobin had a significant inhibitory effect on the growth of fungal isolates from the Tambov region: EC50 is 1.72 μg/l, from the Almaty region EC50 is 2.36 μg/l, from the Saratov region EC50 is 2.63 μg/l. The results of biotesting made it possible to identify isolates of Z. tritici resistant to azoxystrobin: 277-22-5, 277-22-13 (from Kazakhstan); 104-23-9, 104-23-10 (from the Saratov region); 19-23-5, 19-23-8 (from the Tambov region). PCR-RFLP method made it possible to identify mitochondrial mutations G143A in selected fungal isolates, which are associated with the development of resistance to fungicides in the causative agent of septoria. This work is the beginning of a more in-depth study of the sensitivity of the economically significant phytopathogen Z. tritici to fungicides in the territories of Russia and the Republic of Kazakhstan.