Health status of the pear tree following the establishment of Fire blight in Northern Tunisia

Abstract

Pears have great importance in Tunisia for their desirable taste and commercial value. Until 2012, the pear cultivation was protected against fire blight by the application of a rigorous quarantine system. Fire blight, caused by Erwinia amylovora, was outbreak in Tunisia in the spring of 2012 and has spread rapidly through the most important pear growing regions destroying several hundred hectares of pear plantations. Therefore, the total pear production has decreased from 60,000 metric tons in 2011 to less than 20,000 metric tons in 2016. In this study, collected data of pear culture and surveys were carried out during four years (2012)(2013)(2014)(2015)(2016) in the main pear growing areas to evaluate the current situation of the disease in the country particularly in the damaged regions of the lower valley of Medjerda (Manouba, Ben Arous, Bizerte, and Beja). Samples collected from symptomatic trees were processed for the isolation and identification of the causal agent using microbiological and molecular techniques. The results indicate that the disease had destroyed more than 5500 hectares among a total of 8400 hectares of pear plantations area. Both provinces Manouba and Ben Arous were the most affected by fire blight disease resulting in the eradication of 350 and 325 hectares of pear plantations, i.e., 100% and 98% of the total infected area, respectively. All control attempts, including sanitary measures, the application of mineral oil and copper, growth regulators and biological control have failed to limit the spread of the disease. The presence of pathogen in the prospected regions was confirmed by pathogenicity and molecular tests, which are compatible with the symptoms observed throughout the surveys. The pear cultivation in Tunisia is threatened by fire blight due to the restriction tolerance of the available varieties and the climatic conditions favoring the staggered flowering of the species. Quarantine measures must be implemented to prevent the spread of this disease in a new disease-free areas.

First Report of Filamentous Phages Isolated from Tunisian Orchards to Control Erwinia amylovora

“…Tunisia has a long-standing tradition for the cultivation of pears in several areas across the country [ 2 ]. In the past decade, fire blight has been present in regions encompassing Mornag, Manouba and Tebourba [ 3 ].…”

“…In the past decade, fire blight has been present in regions encompassing Mornag, Manouba and Tebourba [ 3 ]. Consequently, E. amylovora is causing devastating economic losses in apple and pear production in Tunisia, with a decrease from 60,000 metric tons in 2011 to less than 20,000 metric tons in 2016 for pear production alone [ 2 ]. In the past, the antibiotic streptomycin was commonly used to control E. amylovora during open bloom [ 4 , 5 ].…”

Effect of Temperatures and Culture Media on Sclerotium rolfsii Mycelial Growth, Sclerotial Formation and Germination

“…Thus, because the environment significantly influences plants, pathogens and their antagonists, changes in environmental conditions are strongly associated with differences in the level of losses caused by a given disease, and environmental changes are often implicated in the emergence of new diseases [2]. Therefore, new, emerging, re-emerging and threatening plant diseases have been reported causing significant yield losses to several crops [3][4][5][6]. Among the re-emerging plant diseases, collar rot caused by Sclerotium rolfsii has become a major limiting factor and the challenging to both farmers and scientists.…”

Isolation of <em>Erwinia amylovora </em>Bacteriophage from Soil and Pear Trees Plant Tissues

“…The symptoms of the disease appeared in 2012 in the region of Mornag and the following year they spread to the regions of Manouba and Tebourba. Percentages of orchard areas of infected plants varied around 100% (3,11). In order to combat this scourge, we started a research and isolation campaign of Erwinia strains in order to identify and characterize them in order to propose treatment solutions.…”