Abstract: Using Botrytis cinerea, Colletotrichum gloeobosporioides, Fusarium oxysporum and Pythium aphanidematum as the model targets, the activity characteristics and the factors affecting the stability and sensitivity of the bactericide were tested. The influence of the model target, compound standard sample and fermentation liquid sample of actinomycetes source standard strain on bactericidal activity was tested by agar diffusion method. The results showed that the treatment process of the target, the content of the target bacteria, the type of sample, and the amount of sample added were directly related to the activity response. Different model targets had different degrees of tolerance to crushing treatment, so it was necessary to conduct personalized treatment for different model targets to ensure the stable growth state of model target bacteria in the test. In the agar diffusion method, not only the bactericidal activity of the sample could be detected, but also the different modes of action of the active ingredient and the target bacteria could be shown. The actinomycete fermentation broth with retained live bacteria showed activity over a wide range of addition amounts, whereas both the actinomycete fermentation broth treated with filtered bacteria and the standard compounds showed activity only when the sample addition amounts were relatively large.

Key words: mode target, bio-fungicide, screening, agar diffusion method, inhibition zone, actinomyces source