Fireblight survey and first characterization of Erwinia amylovora isolates from Algeria.

During field surveys conducted in Spring and Summer 2010-2011, typical fire blight symptoms were observed on twigs and branches of pear (Pyrus communis) and apple (Malus domestica) in Algerian commercial orchards located in the areas of Algiers, Blida, Tipaza and Boumerdes. The disease was observed in 284 orchards, mainly on pear cv. Santa Maria and on apple cvs Royal gala and Golden delicious. Bacterial colonies were isolated on King's medium B (KB) and the semi-selective medium CCT (cycloheximide, cristal violet and thallium nitrate). Bacterial isolates displayed biochemical patterns typical of Erwinia amylovora and reacted positively in a serological slide agglutination test. Pathogenicity of bacterial isolates was confirmed by inoculating immature pear fruits of cv. Conference. The identity of the isolates was further confirmed by nested-PCR, and rep-PCR. A sequenced DNA fragment (713 bp) of the recA gene (accession No. JN812979) matched with 100% identity all E. amylovora recA DNA sequences available in GeneBank.