STUDY OF PATHOGENICITY OF GAEUMANNOMYCES TRITICI - THE TAKE-ALL FUNGUS

Isolates of Gaeumannomyces spp. obtained from diseased roots of winter wheat showing take-all symptoms were characterized by pathogenicity. All isolates were more pathogenic on wheat and barley than on oat, and were identified as G. tritici. Most isolates of G. tritici were characterized as middle pathogenic, the pathogenicity of one isolate was higher than those of others, and two isolates showed the lowest pathogenicity. 30 isolates of dark-colored fungi were isolated from the affected plants of winter wheat, which according to cultural characteristics were previously assigned to the genus Gaeumannomyces. To establish the species affiliation of the selected Gaeumannomyces isolates, we investigated their pathogenicity and specialization on three grain crops: wheat, barley, and oats. All isolates affected the roots of all three crops, but they were more pathogenic on wheat and barley. Based on this feature, they were previously assigned to the subspecies G. graminis var. tritici (now the species G. tritici). The pathogenic properties of the isolates were studied on seedlings of Yelyk wheat plants. All G. tritici isolates analyzed by us showed a high level of pathogenicity. The G. tritici 9/1 isolate was characterized by significantly higher pathogenicity compared to other isolates according to the "disease development" indicator. Most of the other isolates showed medium pathogenicity (3/20, 7/20, 2/16/21, 3/16/21, 16/22), and only two isolates (1/20, 4/16/21) were low pathogenic. In our research, in addition to the "disease development" indicator in points (0-4) to assess the pathogenicity of isolates, we used indicators that characterize the growth and development of plants, namely "weight of 1 seedling" and "mass of roots from 1 seedling". Taking into account the data on these indicators, isolate 9/22 was characterized by significantly higher pathogenicity compared to other isolates: when affected by it, the mass of wheat seedlings and roots was significantly lower than in other variants. Isolates 3/20 and 7/20 were characterized by medium pathogenicity, when infected with them, a significant decrease in the mass of the roots of seedlings was noted. Isolates 16/22 and 3/16/21 showed a low level of pathogenicity - the decrease in root mass was insignificant.