Abstract:Barley grits were used to produce herbicidal Sclerotinia minor Jagger by solid fermentation. Effects of fermentation duration and precursors of oxalic acid on viability, virulence and oxalic acid production of S.minor were measured to provide data for improving its herbicidal effect. S.minor had the highest viability of 65.0 mm when mycelium from liquid fermentation for 7 days was used and the highest virulence of 55.8 mm when mycelium from liquid fermentation for 6 days was used. Herbicide produced from 6 days solid fermentation had the highest viability, virulence and oxalic acid production, which were 64.3 mm, 54.3 mm and 0.131 mg/g respectively. Precursors of oxalic acid had no significant influence on the viability of S.minor. Addition of 56 mmol/L sodium succinate and citric acid raised the oxalic acid production in S.minor by 64.4% and 39.7% respectively and raised its virulence by 12.4% and 5.4% respectively. Positive correspondence was found between oxalic acid production and virulence.