Archivio Journal of Plant Pathology

Abstract:

Fire blight, caused by Erwinia amylovora, a major pathogen of pome fruits and many ornamentals, included in the EPPO A2 list of quarantine organism, was detected in 1990 in the main pome fruit-growing areas of Italy, including Emilia-Romagna where, since 1994, it spread rapidly causing epidemic outbreaks in 1997-1998. In October 2012, during the official monitoring made by the regional Plant Protection Service (PPS), a sample was collected in a nursery in Viterbo province (Latium, central Italy) from a quince plant showing shoot tips withered in the typical 'shepherd’s crook', blackish-brown discoloration of the cortex which, when removed, disclosed the typical red streaks. Following isolation on nutrient sucrose agar (NSA) levan-positive colonies were obtained and purified. The bacterial isolates did not produce fluorescent pigment on CSGA, induced hypersensitive response in tobacco leaves and were oxidase-negative. One isolate (CRA-PAV 1751) was lyophilized and conserved. Specific PCR protocols (Bereswill et al., 1992; Llop et al., 2000; Taylor et al., 2001) yielded amplicons of the expected size. Rep-PCR (using BOX and ERIC primers) fingerprinting pattern was similar to that of the reference strain OMP-BO 1077/7. Pathogenicity tests on immature pear fruits and re-isolation were performed successfully. This is the first report of E. amylovora from Latium, which was declared as "protected zone" by EU Directive 2000/29/EC. Following our finding, the regional PPS has adopted all the measures required by the Ministerial Decree 10/9/99 No. 356, to restrain the spread of the pathogen. This highlights the importance of healthy nursery productions, especially for pathogens like E. amylovora for which prevention is the main control strategy, given that no effective chemical or integrated control methods are available.