One year survival of Erwinia amylovora in symptomless pear scions [Pyrus communis L.]

Pear scions cv Abate Fetel on B29 rootstock were raised individually in pots from dormant buds. In autumn 1999, the main stems were divided into 5 groups and inoculated at 10 day intervals starting from 21 September with a virulent Rif sup (R) mutant of Erwinia amylovora. For the inoculation, 30,000...

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Bibliographic Details
Published in:Journal of plant pathology 2002-11, Vol.84 (3), p.157-160
Main Authors: Traversa, F, Mazzucchi, U. (Bologna Univ. (Italy). Dipartimento di Scienze e Tecnologie Agroambientali)
Format: Article
Language:English
Subjects:
Bacteria
Blight
ERWINIA AMYLOVORA
ESPERIMENTI IN VASO
EXPERIMENTACION EN CONTENEDOR
EXPERIMENTAL INFECTION
EXPERIMENTATION EN POT
Growing seasons
INFECCION EXPERIMENTAL
INFECTION EXPERIMENTALE
Infections
INFEZIONE SPERIMENTALE
INOCULACION
INOCULATION
INOCULAZIONE
Phytopathology
Plants
POT EXPERIMENTATION
PYRUS COMMUNIS
Rootstocks
Scions
Short Communication
SINTOMAS
SINTOMI
SOPRAVVIVENZA
SUPERVIVENCIA
SURVIE
SURVIVAL
SYMPTOME
SYMPTOMS
VARIEDADES
VARIETA
VARIETE
VARIETIES
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Summary:Pear scions cv Abate Fetel on B29 rootstock were raised individually in pots from dormant buds. In autumn 1999, the main stems were divided into 5 groups and inoculated at 10 day intervals starting from 21 September with a virulent Rif sup (R) mutant of Erwinia amylovora. For the inoculation, 30,000 cells of E. amylovora were deposited on a transverse cut 10 cm from the tip. After ensuring establishment of the pathogen, the 5 groups of plants were placed in the open and inspected weekly for the presence of fire blight symptoms. Scions treated with water were used as a control. All symptomatic scions were eliminated by mid-April 2000. The frequency of scions developing symptoms (21.3%) decreased from the first to the last inoculation date (from 5/15 to 1/15). In autumn, a year after inoculation, the plants remaining symptomless were monitored for the presence of endophytic E. amylovora. Reisolation on selective medium was successful in 13 plants out of 41. Reisolation was also successful in 7 segments taken from the side shoots developed from the first and second node below the inoculation point. The results show that E. amylovora can survive a year in symptomless planted scions. Isolation of the mutant from symptomless shoots developed during the growing season following inoculation indicates that E. amylovora may have a prolonged symptomless endophytic phase [Marze di pero cv. Abate Fetel, innestato su B29, derivanti da gemme dormienti, sono state allevate in vaso. Nell'autunno 1999 i fusti principali sono stati divisi in 5 gruppi e sono stati inoculati, a intervalli di 10 giorni a partire dal 21 settembre, con un mutante virulento di Erwinia amylovora. Per l'inoculazione, 30.000 cellule di Erwinia amylovora sono state depositate su un taglio trasversale a 10 centimetri dall'apice. Cinque gruppi di piante infettate sono stati controllati settimanalmente. Tutti i polloni con sintomi sono stati eliminati entro meta' aprile del 2000. La frequenza dei polloni che sviluppavano sintomi (21,3%) e' diminuita dalla prima all'ultima data di inoculazione (da 5/15 a 1/15). In autunno, un anno dopo l'inoculazione, le piante asintomatiche sono state controllate per la presenza di Erwinia amylovora. Un nuovo isolamento su mezzo selettivo ha avuto successo in 13 piante su 41. Il reisolamento ha avuto successo anche in 7 segmenti presi dai getti laterali sviluppati dal primo al secondo nodo sotto l'inoculazione. I risultati indicano che Erwinia amylovora puo' sopravvivere
ISSN:1125-4653
2239-7264