Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First report of fire blight caused by Erwinia amylovora on pear in Tunisia.

Abstract

In the spring of 2012 and 2013, symptoms similar to those of fire blight were observed on pear (Pyrus communis) trees in Tunisia at the flowering stage. Disease symptoms appeared in 2012 in the region of Mornag and in the following year extended to the regions of Manouba and Tebourba. More recently, the disease was observed in the regions of Bizerte, Zaghouan, and Beja. The percentage of orchard areas that had infected plants varied from 10 to 40%. Some orchards in Mornag region exhibited more than 75% disease incidence. Symptoms were observed on flowers and young shoots. Blighted blossoms appeared wilted, shriveled, and brown, and dead flowers remained on the stems. Infected shoots wilted rapidly and often formed shepherdacute╦ťs crooks at their tips. Samples of diseased young shoots and flowers were subjected to pathogen isolation and identification. Colonies with morphology similar to that of E. amylovora were purified. The pathogen was identified as E. amylovora by double-antibody sandwich indirect-ELISA and immunofluorescene microscopy using a polyclonal antibody and nested PCR targeting the pEA29 plasmid. This is thought to be the first report of fire blight caused by E. amylovora on pear in Tunisia.