Race identification of Pseudomonas solanacearum E. F. Smith in Egypt.

Twenty one isolates of Pseudomonas solanacearum E. F. Smith, which does not occur on hosts other than potato in Egypt, obtained from diseased potato tubers, were collected from different localities in Egypt and used in this study. These 21 isolates were found pathogenic to potato plants, but they were not pathogenic to tobacco and banana plants. All the 21 isolates caused only a yellowish discoloration of the infiltrated area of tobacco leaves by 48 hrs after inoculation and produced low melanin pigments on a tyrosine agar medium. These results indicate that the obtained isolates belong to Race 3. Biochemical studies, performed on five representative isolates, indicated that they all belong to the biochemical biotype II. The results obtained in the present investigation appear to be the first record of P. solanacearum races in Egypt.