ISHS Acta Horticulturae 273: V International Workshop on Fireblight
BACTERIAL COLONIZATION OF FLOWERS AND LEAF SURFACE OF PEAR TREES |
| Authors: | C. MANCEAU, J. LALANDE, G. LACHAUD, R. CHARTIER, J. PAULIN |
| Abstract:
In 1988, 200 flowers and 500 leaves were collected weekly in a commercial Passe-Crassane orchard with an history of fire blight since 1984. Bacterial populations were monitored by washing organs with distilled water and plating serial dilutions on King's B agar. A special regard was applied to E. amylovora, E. herbicola, P. syringae, P. fluorescens and yellow pigmented pseudomonads. E. amylovora was never recovered from healthy flower as well as from healthy leaves throughout the growing Season with the exception of leaves located just under active oozing symptoms. E. herbicola and P. fluorescens were detected from time to time and sporadicaly in the orchard on flowers and leaves. Conversely, P. syringae and yellow pigmented pseudomonads were detected early on flowers. The populations increased during bloom period and spread all over the sampling plots. Thereafter their populations were detected on almost each sampled leaf and remained at high level (104 to 105 c.f.u./leaf) during all the growing season. These results confirm that E. amylovora had not an epiphytic fitness in its biological cycle under our conditions, either on flower or on leaf. P. syringae and yellow pigmented pseudomonads were better epiphytes than E. herbicola and P. fluorescens and could be good candidates as potential biological control agents, provided some antagonistic bacteria can be found among them. | |
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