The invention discloses actinomycetes for preventing and treating peanut diseases and application of actinomycetes .The name of strain LX14 is Streptomyces lavendulae, the preservation unit is Center of general microbiology of China Committee for Culture Collection of Microorganisms, the preservation time is January 22, 2014, and the preservation number is CGMCC No.8806 .Metabolin Streptomyces lavendulae is screened out from soil in a separation mode, is high in restraining effect on peanut fungi, is applied to preventing and treating peanut crown rot pathogen, a peanut scab disease, peanut root rot and peanut southern blight, has important significance in peanut disease preventing and treating and is very important in plant disease biological preventing and treating; a new approach is added for development of agricultural fungicide, and the Streptomyces lavendulae has good development and application prospects.