Preserving of the aggressiveness of strains of fungi from a genus Fusarium infecting sunflower in a culture on the different substrates and temperature regimen

Species of a genus Fusarium Link. are the most spread fungi infecting agricultural crops including sunflower. Breeding for the resistance promotes the decrease in spreading and development of diseases but to choose breeding material it is necessary to use the most aggressive strains of pathogen. The purpose of the research was to conduct a comparative analysis of preserving of aggressiveness of strains of two species from the genus Fusarium infecting sunflower in a clear culture on the different vegetal substrates. The object of the research was species F. sporotrichioides Sherb. and F. oxysporum (Schlecht.) Snyd. et Hans. var. orthoceras (Appl. et Wr.) Bilai, isolated from the sunflower roots infected with fusariosis. There is presented a range of variability of these strains aggressiveness at preserving temperature +4 °C and +22-28 °C on sterile sunflower seeds, husks, and fragments of plants du ring five months. When preserving the strains of both species at a temperature of +22-28 °C on seeds the significant decrease of the aggressiveness was stated on the third month and on husks - on the forth one. At lowered temperature of +4 °C the aggressiveness of F. sporotrichioides was decreasing insignificantly on sunflower stems and husks during five months, the important decrease of the aggressiveness of F. oxysporum var. orthoceras was stated on the fourth month. We estimated the more aggressive species F. sporotrichioides preserve the high aggressiveness during longer time (five month) than F. oxysporum var. orthoceras .