Abstract

Alternaria fungi are the most common pathogens that infect tomato at all stages of the growing season. Therefore, this study was conducted during 2017-19 at Federal State Budgetary Scientific Institution-All Russian Scientific Research Institute of Biological Plant Protection (FSBSI ARSRIBPP), Krasnodar, Russia aimed to study the species composition and Alternaria populations structure Krasnodar Krai, as well as to identify new sources of resistance genes to tomato alternaria leaf spot. In the course of the research the species composition and structure of Alternaria populations collected in various agroclimatic zones of Krasnodar Krai were studied. It was found that all the collected isolates belong to the Alternaria alternata species. A collection of aggressive strains of this species was formed and their virulence was assessed on 26 tomato lines of the collection of the FSBSI ARRIBPP. The studies were carried out on an artificial infectious background in the field and under the laboratory conditions. In the field experiments, the Mo 509 genotype showed the highest resistance to alternaria leaf spot. 16 genotypes showed a relatively high resistance and moderate resistance. As a result of the laboratory experiments, we found no samples completely immune to the seven studied A. alternata strains. Lines 46, 509, 685 showed resistance to four strains; lines 172 and 316 - to three strains; line 568 - to two strains; line 500 - to one strain. A significant correlation was noted between the results of the field and the laboratory assessments (r = 0.63–0.72, P <0.01). As a result of the studies, pre-selection resources were obtained for the cultivation of tomato varieties tolerant and resistant to various A. alternata s. strains.