Abstract: Using [Cynodon dactylon (L.) Pers.] and (Amaranthus retroflexus L.) as materials three different screening methods were used to screen the activity of microbial herbicides in laboratory. The results showed that the microplate method was suitable for the screening of quick acting compounds or active ingredients. It had the advantages of large screening flux, strong operability and less sample dosage. However, it could be used for the preliminary screening of compound activity due to its short culture time and poor anti pollution ability, but it was not suitable for the screening of microbial fermentation broth or living bacteria samples; The metabolism of the leaves in vitro is slower than that of the leaves in vivo, and the growth point almost stops growing, which can not fully reflect the activity of the samples to the leaves in vivo; The mini pot method is suitable for screening samples with complex components. The results are close to the advantages of field medication, strong pollution resistance and long observation time, but the dosage is relatively large, the operation is complex, and the screening flux is limited.

Key words: microbial herbicide, herbicidal activity, seeds treatment, leaves treatment