Colonization of barley roots by Fusarium culmorum and influence of Pseudomonas fluorescens on the process

The stages of barley root colonization by Fusarium culmorum were studied in sterile vermiculite by the method of fluorescent antibodies. The influence of the antagonistic bacterium Pseudomonas fluorescens on the process of root colonization by F. culmorum was demonstrated. In vermiculite inoculated with F. culmorum, the fungus density on the roots increased gradually. In the case of joint inoculation of vermiculite with the fungus and the bacterium, the F. culmorum density on the roots changed abruptly. It was shown that the site of primary colonization of the roots by the fungus was mainly the zone of root hairs. When Pseudomonas fluorescens was present on the roots, F. culmorum colonized not only root hairs, but also the elongation zone, during the first two days. Introduction of Pseudomonas fluorescens into vermiculite resulted in lower intensity of barley root rot.