Isolation and Characterization of Opine-Utilizing Strains ofAgrobacterium tumefaciensand Fluorescent Strains ofPseudomonasspp. from Rootstocks ofMalus

Media containing opines were used to isolate Agrobacterium tumefaciens and fluorescent Pseudomonas spp. from rootstock tumors and roots of Malus. Strain B49C of A. tumefaciens was used to inoculate cultivars Mark, EMLA 7, and Red Delicious seedling apple rootstocks in field trials at two nurseries in Washington state. Crown gall incidence was greater and inoculated than on uninoculated controls at both locations. Of 12 strains of A. tumefaciens isolated, three utilized mannopine, four utilized nopaline, and four utilized both mannopine and nopaline as the sole carbon and nitrogen source in culture media (...)