THE DISEASE SUPPRESSIVENESS OF LIGHT-COLOURED SPHAGNUM PEAT AND BIOCONTROL OF PLANT DISEASES WITH STREPTOMYCES SP.
The effect of spore suspension and powder, prepared by fermentation and freeze-drying of Streptomyces griseoviridis to control plant diseases was tested. Damping-off caused by Alternaria fungi was controlled by seed dressing with Streptomyces as effectively as by chemical seed dressing with thiram. Dressing the cucumber seeds reduced the proportion of poor-quality seedlings and the mortality rate of seedlings. Spraying the preparate on the surface of the peat substrate increased the average yield of cucumber. The largest annual yield increases were 9 - 12%. Treating the peat surface decreased the disease incidence of Fusarium wilt of carnation, cyclamen and gerbera.
Several isolates of Streptomyces species obtained suppressed fungal growth on agar and produced a heptaene polyene antibiotic. There was a significant difference in the antibiotic production between suppressive and nonsuppressive isolates. Heptaene polyene was determined in peat treated with Streptomyces sp.