Efficient biological control of fungal plant diseases by Streptomyces sp DSMZ 12424

The actinomycete Streptomyces sp. DSMZ 12424 (HRO71) was originally isolate d from the rhizosphere of strawberry and shown to be an effective antagonis t in vitro toward several plant pathogenic fungi. Mechanisms of fungal inhi bition were elucidated by tracing secondary-metabolite production and funga l cell wall-degrading activity. Streptomyces sp. DSMZ 12424 produced sidero phores and antibiotics and showed chitinolytic activity. Additionally, the production of the plant growth hormone indole-e-acetic acid was found. When Streptomyces spores were used to coat sugar beet seeds, che emergence rate of treated plants in soil infested by Rhizoctonia solani and Pythium ultim um in comparison to the untreated control was enhanced. The bacterium was a ble to suppress plant pathogenic fungi in different pathosystems: (a) sugar beet - Rhizoctonia solani, (b) lambs lettuce - Phoma valerianellae and, (c ) cress - Alternaria sp. DSMZ 12424 was added using seed coating (a) and se ed infiltrating techniques (b, c). The biocontrol agent was formulated as w ater dispersable granules. The spores are conserved in the product and they can be stored at least 1 year without significant loss of activity. Finall y, on the basis of Streptomyces sp. DSMZ 12424 a microbial product was deve loped and called Rhizovit (R).