Abstract
An antagonistic bacterium belonging to genus Pseudomonas isolated from citrus canker lesions considerably inhibited the multiplication of citrus canker bacterium (Xanthomonas campestris pv. citri) not only in PS medium but also in the tissues of citrus leaves. In PS medium, the lower the concentration of the medium was, the less degree of the inhibition was resulted. It suggests that suppression of multiplication of X. campestris pv. citrt by antagonistic bacterium was not caused by the competition for nutrients. The multiplication of antagonistic bacterium was not supprssed by citrus canker bacterium in PS medium, but rather promoted in the diluted medium. In the citrus leaf tissue inoculated with both bacteria by needle pricking at the same time, the antagonistic bacterium suppressed considerably the growth of X. campestris pv. citri. The suppression, however, was not so remarkable when both bacteria were infiltrated into intercellular spaces. The antagonistic bacterium introduced alone either by needle prick inoculation or infiltration in to citrus leaf tissues increased its number remarkably with in a few days, but subsequently it decreased gradually. In case of mixed inoculation, the multiplication of antagonistic bacterium in the inoculated tissue was greatly enhanced and longevity of the bacterium was extended as compared to those of single inoculation.
