No abstract

No abstract

Populations of Erwinia amylovora bacteriophage greater a spreading translucent halo and a smaller plaque without a than 106 plaque-forming units (PFU) per gram of tissue were halo. Thirty-five bacterial isolates, consisting of nine genera, isolated without enrichment from diseased aerial parts of 18 species, and 15 strains of E. amylovora were typed; the apple trees during the summer of 1975. Three phage isolates phages lysed only E. amylovora. The burst size of the three were selected from different geographical locations. Two isolates was 40 to 50 PFU per cell. The phages could be stored types of plaques were produced; a clear-centered plaque with at 4 C and-20 C but lost titer when stored at 24 C.

A yellow bacterium which had inhibited Erwinia arnylovora was identified as Errvinia herbicola. Erwinia herbicola occurred on leaf surfaces in large numbers on apple, cherry, and apricot trees, but in small numbers on pear leaves. It was not pathogenic, but was a secondary invader of diseased tissues. Fire blight branch cankers were examined for occurrence and location of E. amylovora and E. l~erbicola. Erwinia herbicola occurred mixed with E. amnylovora. Both bacteria were isolated at maximum frequency about 7.6 c n~ above the edge of downward advancing cankers.Partial control of fire blight was obtained in the greenhouse and field plots by inoculation of pear blossoms with E. llerbicola 24 h before inoculation with a virulent suspension of E. amylovora. The inhibitory effect could occur in pear blossom nectar. On media containing sugar concentrations comparable to pear nectar, E. Irerbicola consumed all organic nitrogen in the medium and reduced the pH to a level inhibitory to E. amylovora. RIGGLE, J. H., et E. J. KLOS. 1972. Relationship of Erwinia herbicola to Erwirzia amylovora. Can. J. Bot.50: 1077-1083. Une bactkrie jaune qui avait inhibe Erwinia amylovora a Ct C identifiie cornme Erwinia herbicola. Erwirzia herbicola a kt6 rencontre en grandes quantitCs sur la surface de feuilles de pomrniers, de cerisiers et d'abricotiers, mais en quantite plus faible sur les feuilles de poiriers. I1 n'ktait pas pathogtne rnais Btait un envahisseur secondaire des tissus rnalades. Des chancres de la briilure sur les branches ont tte examint% pour determiner I'abondance et la localisation de E. amylovora et de E. herbicola. Erwinia herbicola a etB rencontre en mdange avec E. amylovora. Les deux espbes de bactkries ont Bte isolQs $ une fr& quence maximale environ 7.6 cm du front infkrieur d'avance du chancre sur la branche.Un contrble partiel de la briilure a kt6 obtenu en serres et en parcelles experimentales en inoculant des boutons floraux de poire avec E. herbicola 24 h avant I'inoculation avec une suspension virulente de E. amylovora. L'effet inhibiteur pourrait se trouver dans le nectar de la fleur du poirier. Sur des milieux contenant des concentrations de sucre cornparables a celles du nectar de poire, E. herbicola a consommC tout l'azote organique dans le milieu et a reduit le pH a un niveau inhibiteur pour E. amnylovora.

No abstract