occurrence and distribution of shallow bark canker of walnut trees in northern provinces of iran

in recent years, shallow bark canker of walnut (juglandis regia l.) trees has become fairly widespread in iran. to determine the distribution of the disease in golestan, mazandaran and gilan provinces, from early summer to mid-fall seasons of 2004, more than one hundred bark samples were collected from walnut trees showing symptoms of shallow bark canker. sixty strains of bacteria were isolated from the infected tissues. strains appeared to be more or less similar in phenotypic characteristics. in spite of some differences in their electrophoretic profiles of whole-cell proteins, on the basis of the results of morphological, biochemical and physiological tests the bacterium was identified as brenneria nigrifluens (wilson) hauben et al., 1998. this is the first report of shallow bark canker of walnut trees in golestan and gilan provinces.