Abstract: The antifungal activity and the field control effects of Psoralea corylifolia seeds extract against Exobasidium vexans were explored. The spore germination inhibition rate method and mycelium growth rate method were used to determine the antifungal activity of Psoralea corylifolia seeds extract, and the field trials of Exobasidium vexans were carried out in five provinces and five places according to the pesticide field efficacy trials guideline. The indoor antifungal activity test showed that Psoralea corylifolia seeds extract had an obvious inhibitory effect on the spore germination and mycelium growth of Exobasidium vexans, and the inhibition rate increased with the increase of drug concentration, with the EC₅₀ of 12.925 mg/L and 6.074 mg/L, respectively. The results of field trials showed that when the dosage of active ingredients of Psoralea corylifolia seeds extract microemulsion was 2.00~2.67 mg/kg, the field control effects of Exobasidium vexans was 68.08%~83.78%, which was equivalent to or better than that of the control agent 3% polyoxin wettable powder.

Key words: biological pesticide, tea cake disease（Exobasidium vexans Massee）, antifungal activity, field control effects, Psoralea corylifolia seeds extract