ISHS Acta Horticulturae 217: IV International Workshop on Fire Blight
ORCHARD EVALUATION OF FIVE STRAINS OF ERWINIA HERBICOLA FOR CONTROL OF BLOSSOM INFECTION |
| Authors: | S.V. Beer, J.R. Rundle, J.L. Norelli |
| Abstract:
Five strains of Erwinia herbicola that appeared most promising in earlier experiments were tested for their ability to control the blossom blight phase of fire blight in the research apple orchard. Each strain was grown in dilute nutrient-yeast-extract-glucose broth to late log phase. Suspensions were diluted in tap water to ca. 1 x 108 colony forming units (cfu) per ml and sprayed on blossom clusters of 'Idared' apple. A water check and streptomycin (100 mg/ml) were also included. Each treatment was applied to eight trees situated in randomized complete blocks. The first application was made when about 75% of the blossoms were open. One day later at full bloom, the same blossom clusters were inoculated with about 2 x 107 cfu/ml of E. amylovora. A second application of the test treatments was made later on the same day. In the water (control) treatment, 26% of the clusters became infected. The bacterial treatments reduced infection by an average of 57%, and did not differ significantly from each other. Streptomycin reduced infection by 84%, which was significantly greater control than that provided by two of the bacterial strains. Low infection in the water control, compared to previous years, likely was due to cool dry conditions following inoculation. | |
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