Abstract: The time series analysis and biological activity of toxin of Sclerotinia sclerotiorum were carried out by artificial culture and inoculation test. The results showed that the main toxin product produced by S. sclerotiorum was oxalic acid, and the concentration of oxalic acid increased gradually with the mycelium growth. When the growth rate of pathogen was the fastest, the content of oxalate reached the maximum value, and the pH correspondingly decreased to a minimum. Oxalate could regulate the pH of the culture matrix. The combined action of oxalic acid and mycelium could effectively infect host tissues, and oxalate toxin had a strong inhibitory effect on seed germination vigor, seedling growth and plant development of pepper.

Key words: Sclerotinia sclerotiorum, toxalic acid toxin, biological activity