Abstract
Strains of Xanthomonas campestris pv. citri (Hasse 1915) Dye 1978 isolated from citrus canker in Japan (canker A) and those from cancrosis B in Argentina (canker B) were compared by pathological, physiological, serological and phage susceptibility properties. Strains of canker B organism were characterized by being significantly less virulent than those of canker A organism on various citrus plants such as Unshu, Natsudaidai, lemon and navel orange. Strains of canker B organism also differed from those of canker A organism in small size of colonies on agar plates, delayed lag period in liquid media, inability to utilize lactose and maltose, susceptibility to a new phage Cp 3, and lack of an antigenic component of the latter. Ten out of twenty-one strains of canker B organism were unable to utilize malonate which was consistently utilized by strains of canker A organism. All strains of canker B organism utilized mannitol, while one-half of the strains of canker A organism did not utilize this substrate. It was concluded that such differences supported the differentiation of canker B organism as a distinct group within the pathovar of X. campestris pv. citri.
