ISHS Acta Horticulturae 151: III International Workshop on Fire Blight
ERWINIA AMYLOVORA DETECTION AND ITS SIGNIFICANCE IN SURVIVAL STUDIES |
| Author: | H.J. Miller |
| Abstract:
Epiphytic studies were carried out during the summer of 1983 on samples taken from two sites in the Netherlands with the purpose of comparing and utilizing the results obtained by isolation and immunofluorescence microscopy (IF) methods. From one site at Horst, where fireblight has never been reported, pear leaves were collected every week. Only very low numbers of morphologically typical fluorescent cells were detected and in no case was Erwinia amylovora isolated. At a second site at Ouwerkerk, where a natural fireblight source is maintained for study, leaves were collected from pear buffer trees not visably infected and from non-infected parts of Cotoneaster bullata which had otherwise fireblight symptoms. From pear two cultures were obtained and four possible cases of dead epiphytic E. amylovora were indicated by IF. Samples from C. bullata produced three live cultures but the IF did not indicate further epiphytic presence of E. amylovora. The detection level of the IF method was estimated at 8.5 X 103 cells/ml. The survival period of E. amylovora in a true epiphytic state is undoubtedly very short. Under the conditions at Ouwerkerk the results indicate the importance of epiphytic E. amylovora to be overestimated and that the short-range blossom infections were most probably caused by bees or other insects. | |
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