Etiology of apple tree dieback in tunisia and abiotic factors associated with the disease

Abstract

[EN] An apple tree dieback syndrome causing severe tree losses was observed in the main apple producing regions in Tunisia from 2006-2008. This work aimed at identification of the causal agents and the factors that promote apple tree dieback. The causal agents of the syndrome included the following: Phytophthora and Pythium species: Phytophthora parasitica and Phytophthora inundata, Pythium sp., Pythium indigoferae, Pythium irregulare, Pythium rostratifingens, Pythium sterilum and Pythium undulatum. Molecular techniques confirmed the results of the morphological identification. Pathogenicity assays showed the involvement of these pathogens in apple tree dieback. Soil salinity was also shown to be an important factor of disease severity in this study.