Fire blight (Erwinia amylovora [Burrill] Winslow) in Morocco: importance, geographical distribution and characterization

Fire blight, caused by Erwinia amylovora, was detected in Morocco in 2006 and has spread rapidly throughout the most important pome fruit-producing regions. Surveys were carried out in 2009 in the main pome fruit-growing areas in Morocco to evaluate the current situation of the disease in the country, particularly in the El Hajeb region, where important losses due to this pathogen were recorded. Samples showing symptoms associated witho the disease were collected from affected apple (Malus domestica), pear (Pyrus communis) and quince (Cydonia oblonga) trees and processed for the isolation and purification of the causal agent. Other isolates collected in the period 2006-2008 were also included in this study. All the isolates were identified to genus and species levels using morphological, biochemical and serological tests. Confirmation tests were carried out using classical PCR and Real-time PCR. Forty eight Moroccan isolates were confirmed to belong to E. amylovora. Fingerprinting methods (rep-PCR and fAFLP) showed a diversity of the isolates and resulted in grouping them in four separate subgroups. This study suggests that Moroccan isolates of E. amylovora have multiple geographical origins.