EVALUATION OF STREPTOMYCES FOR BIOCONTROL OF BIPOLARIS-SOROKINIANA AND SCLEROTINIA-HOMOEOCARPA ON THE PHYLLOPLANE OF POA PRATENSIS

Several species of Streptomyces were evaluated for their ability to co ntrol Sclerotinia homoeocarpa (dollar spot) and Bipolaris sorokiniana (leaf spot) on the phylloplane of Poa pratensis (Kentucky bluegrass). Species evaluated included S. diastaticus (S32), S. galbus (S35), and S. hygroscopicus (isolates S13, S28). All evaluations were conducted o n the upper epidermis of intact attached leaves of P. pratensis, and a ntagonism was measured as the ability of Streptomyces isolates to prev ent chlorophyll loss from leaves inoculated with B. sorokiniana or S. homoeocarpa during pathogenesis. Only S. hygroscopicus (S13) effective ly prevented infection and subsequent chlorophyll loss from leaves ino culated with B. sorokiniana or S. homoeocarpa. Isolate S28 of S. hygro scopicus showed erratic antagonism of both pathogens, depending upon h ow the isolate was prepared for use. Streptomyces diastaticus and S. g albus were antagonistic to S. homoeocarpa only in whole culture form.