2.1. Isolation of antagonistic actinomycetes
An antagonistic microorganism was isolated from the rhizo-
sphere soil of a healthy strawberry plant in strawberry-growing
areas in Kylin, Jiangsu Province. The soil suspension was serially
diluted 10-fold, spread on Gauze’s No. 1 medium, and incubated at
28 C for 5–7 days. Purified colonies were screened for antagonists
against different fungal pathogens on plates using the dual culture
method described by Suárez-Estrella et al. (2007). The strain
showing the strongest antifungal effect was coded as B04 and
selected for further studies. The phytopathogenic fungi were
Verticillium dahliae,F. oxysporum f. sp. melon and F. oxysporum Y3.
F. oxysporum Y3 was isolated from infected root tissues of
strawberry and thereby confirmed as the responsible pathogen
by procedures described in Koch’s postulation in the pot experi-
ments (Shen et al., 2015).