The present invention relates to antifungal biocontrol agents which enhance plant growth and reduce plant diseases by suppressing fungal pathogens, and the manufacturing and application methods thereof. The antifungal biocontrol agents of the present invention consist of one of the newly isolated strains of Streptomyces sp. WYE 20 (KCTC 0341BP) and WYE 324 (KCTC 0342BP) and a delivery medium which canies and stabilizes the cells. In particular, WYE 20 and WYE 324 of the present invention exhibit strong antifungal activity against Rhizoctonia solani and Phytophthora capsici and can be used in various ways to reduce fungal diseases in plants such as cucumber (Cucumis sativus L.), pepper (Capsicum annuum L.), and golf course turfgrasses.
