Pome and stone fruit trees as possible reservoir hosts for Phaeoacremonium spp., the causal agents of grapevine esca disease, in Iran

Abstract

Phaeoacremonium spp. are known as the main Hyphomycetes associated with esca disease symptoms on grapevines worldwide. The role of other woody hosts in proximity of vineyards as a possible inoculum source for the causal agents of grapevine esca disease mainly remains unknown. The aim of this study was to investigate the occurrence of Phaeoacremonium spp. on pome and stone fruit with trunk diseases symptoms in northwestern parts of Iran. For this purpose, wood trees samples were collected from apple and apricot trees with trunk disease symptoms. Isolation was made using routine plant pathology methods. Based on the morphological and cultural characteristics, Phaeoacremonium aleophilum and Phaeoacremonium iranianum were identified from apple trees and P. aleophilum was recovered from apricot trees with trunk disease symptoms. A phylogenetic analysis based on the sequence data from β-tubulin gene further confirmed the identity of the species as P. aleophilum and P. iranianum. The results of inoculation assay on detached shoots of apples revealed that P. iranianum is pathogenic on apple. Our results also showed that P. aleophilum isolates from different hosts (apple, apricot and grapevine) were pathogenic on apple and induced wood discolouration on apple stems. There was no significant difference on the length of lesions induced in relation to the origin of the P. aleophilum isolates. This study is the first report on the occurrence of P. iranianum on apple trees with trunk disease symptoms worldwide and the first report on the occurrence of P. aleophilum on apple and apricot in Iran.

Keywords:

• alternative host
• wood necrosis
• grapevine dieback
• trunk diseases
• Vitis vinifera

Acknowledgements

The authors would like to thank the Research Deputy of the University of Tabriz and the Studienstiftung Mykologische Systematik und Ökologie for financial support.