Antifungal effect of some steroidal glycoalkaloids on monilinia fructigena (ADERH. & RUHL.) honey fungus

Abstract

Monilinia fructigena is the pathogen responsible for the appearance of brown rot and mummification of apple fruit present anywhere this species is grown. In Romania, the fungus attack is frequently in the apple orchards every year, depending on the environmental conditions, variety resistance, pathogen control management. The antifungal activity aainst this pathogen of steroidal glycoalcaloids extracted from Solanum species was tested in vitro. The steroidal glycoalkaloids considered were: solanine, solanidine, tomatine, solamargine, chaconine. Of these, a structural group, encoded GLY, was selected as one of the active components of a patented biofungicide. It was tested in concentrations of 0.1%, 0.5% and 1% and compared with the control. The biological material was represented by the isolated Monilinia fructigena (Mf 7), collected on apple fruit, the Idared variety, originated from RIFG Maracineni. The fungus did not develop in the first 3 days of incubation in any of the experimental variants. After 6 days of observation, the fungus developed at variants of GLY 0.1%, GLY 0.5% and control. The maximum mycelial diameter was determined in the control variant with 73.3 mm after 12 days of observation. In the GLY0.1% variant the diameter of the colony was 50 mm and in the GLY 0.5% variant the diameter of the fungus colony reached 8.2 mm, after 12 days of observation. In GLY 1% variant fungus did not develop throughout the observation period. Efficacy was maximal (E = 100%) in the GLY1% variant, followed by the GLY0.5% variant, with the efficacy of 88.8%. The EC 50 and EC 90 values were 0. 21% and 0.75% for the data obtained after 12 days of observation.