Fungal community associated with grapevine wood lesions in Lebanon

Abstract

<p style="text-align: justify;"><strong>Aims</strong>: To detect and identify the cultivable microorganisms putatively associated with esca disease in representative Lebanese vineyards.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Two field surveys were conducted in Lebanon in 2005 and 2007 to study the fungal community associated with grapevine wood lesions. A total of 68 vines showing typical esca symptoms were randomly sampled in 17 vineyards and cross sections were obtained of cordons and trunks. The shape and type of inner necrosis and discoloration were examined and isolations were made from the symptomatic wood. Isolation results showed that inner necrosis and isolated fungi were similar to those previously found elsewhere, namely in Central Europe or Mediterranean countries. Additionally, three methods for numerical evaluation of micro-organisms found were compared.</p><p style="text-align: justify;"><strong>Conclusion</strong>: Most fungal pathogens generally associated with grapevine trunk diseases were detected, of which the basidiomycete <em>Fomitiporia mediterranea</em> and species of the ascomycete family <em>Botryosphaeriaceae</em> were the most frequently encountered. Additionally, a large diversity of other wood colonizing micro-organisms was detected. The putative role of some of the obtained micro-organisms in the process of wood degradation related to esca disease is discussed.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This isolation study is presently the most completed that was carried out with grapevine wood samples collected in Lebanon. Besides, it is the first to provide isolation results based on a classification of inner necrosis in five categories and to compare three criteria for numerical evaluation. This study also tends to further highlight that <em>Botryosphaeriaceae</em> species are common wood inhabiting fungi that should be associated with esca.</p>