SOIL INTRODUCTIONS OF BACILLUS SUBTILIS AS BIOCONTROL AGENT AND ITS POPULATION AND ACTIVITY DYNAMIC

Bacillus subtilis, produced by the FZB Biotechnik GmbH Berlin as biocontrol agent effective against different soil-borne fungal diseases in vegetables, omamental and agricultural plants, was studied after seed and soil applications in its behavior in soil and rhizospheres.
It is shown that by seed application introduced bacterial spore populations colonize the rhizosphere and rhizoplane along the roots far away from the seed up to 2 month of root growth at least.
Spore populations can establish and survive for long times in different treated soil types.
The ability to biocontrol pathogens is a long lasting stable activity of the soil introduced B. subtilis populations.
Plant growth promoting activities on the other hand have been found more with young bacterial populations and under certain ecological conditions only.
Stimulating factors for growth and phytosanitary activities of B. subtilis are mainly higher temperatures, also a 60°C heat shock, and sufficient soil moisture.
Inhibiting effects on introduced B. subtilis may arise from competitions by autochthone soil microbes.
The observations were discussed for optimal use of B. subtilis as biocontrol agent.

IV International Symposium on Soil and Substrate Infestation and Disinfestation

H. BOCHOW, K. GANTCHEVA

https://doi.org/10.17660/ActaHortic.1995.382.17