Bioactivity Screening of 9 Kinds of Plant Extracts Against Plant Pathogens in vitro

The antifungal activities of 9 kinds of plant extracts by ethanol were tested in vitro against plant pathogens. The method of hypha growth rate was used against 6 plant pathogens, i.e. Valsa mali, Gibberella zeae, Physalospora piricola, Fusarium oxysporum f. sp. vasinfectum, Colletotrichum gleosporioides and Fusarium oxysporum f. sp. cucumarinum. The results showed that at the concentration of 5 mg/mL, the flower extract of Vitex negund var. Heterophylla had certain inhibition to the 6 kinds of plant pathogenic fungus, in which the inhibitory rates against V. mali, F. oxysporum f. sp. vasinfectum, P. piricola and F. oxysporum f. sp. Cucumarinum were 91.07%, 72.97%, 64.54% and 63.20% respectively. The method of inhibition spore germination was tested with 9 kinds of plant alcoholic extracts against 2 kinds of plant pathogenic fungus, F. oxysporum f. sp. cucumarinum and C. gleosporioides. The results showed that at the concentration of 20 mg/mL, the inhibition rates of the leaves alcoholic extracts of Cedrus deodara and Agrimonia pilosa were 100%.