Abstract: To clarify the bioactivities of the botanical substances against pathogens， the antibactierial effects of ethanol extracts of the bark of Chinensis Phellodendron， Melia azedarach， Rheum palmatum， et al. and their mixtures were studied. The results showed that the bioactivity of 0.5% berberine AS was highest to many fungi. It was also found that 0.5% berberine AS had high toxicities against some vegetable pathogenic fungi, slight toxicities against people and livestock and low biological toxicity to environment. All the efficacies of 0。5% berberine AS diluted to 400 times against Sphaerotheca fuliginea， Phytophthora capsici and Jclerotinia sclerotiorum， were above 75% in the field.

Key words: berberine, bioactivity, toxicity, field efficacy