A DNA APPROACH TO ERWINIA AMYLOVORA DETECTION IN LARGE SCALE APPLE TESTING AND IN EPIDEMIOLOGICAL STUDIES

A close correlation exists between the results of intensive apple orchard inspections for fire blight symptoms and tests for Erwinia amylovora in fruit calyxes.
Using a sensitive DNA hybridization method, (³²P-labelled probe), c.60000 apple fruit calyxes were tested from 10 orchards free of fire blight symptoms and no Erwinia amylovora was detected.
The orchards were each characterised by a surrounding 250m zone containing no alternative hosts of Erwinia amylovora and a 500m zone containing no hosts with fire blight symptoms.

The DNA probe was used to determine the distribution of Erwinia amylovora from inoculated blight sources (flowers) showing disease symptoms and Erwinia amylovora was not detected in calyxes of either immature or mature apple fruit, even from within 20cm of these blight sources, in a season not conducive to the spread of the disease over flowering.

VI International Workshop on Fire Blight

R.G. Clark, C.N. Hale, D. Harte

https://doi.org/10.17660/ActaHortic.1993.338.7