Trunk Surgery as a Tool to Reduce Foliar Symptoms in Diseases of the Esca Complex and Its Influence on Vine Wood Microbiota.

Andrea Pacetti,Laura Mugnai,Catia Pinto,Samuele Moretti,Sibylle Farine,Stéphane Compant,Christophe Bertsch

doi:10.3390/jof7070521

Abstract

In the last few years, trunk surgery has gained increasing attention as a method to reduce foliar symptoms typical of some of the Esca complex diseases. The technique relies on the mechanical removal of decayed wood by a chainsaw. A study on a 14-year-old Cabernet Sauvignon vineyard was carried out to validate the efficacy of trunk surgery and explore possible explanations behind it. Three levels of treatment were applied to three of the most characteristic symptoms associated with some diseases of the Esca complex, such as leaf stripe symptoms (LS), wilted shoots (WS) and apoplexy (APP). The most promising results were obtained by complete trunk surgery, where the larger decay removal allowed lower symptom re-expression. According to the wood types analyzed (decay, medium and sound wood), different changes in microbiota were observed. Alpha-diversity generally decreased for bacteria and increased for fungi. More specifically, main changes were observed for Fomitiporia mediterranea abundance that decreased considerably after trunk surgery. A possible explanation for LS symptom reduction after trunk surgery could be the microbiota shifting caused by the technique itself affecting a microbic-shared biochemical pathway involved in symptom expression.

Highlights

Wood diseases are a major threat for modern viticulture, and the diseases included within the Esca complex remain the most worrying in Europe and worldwide [1,2]
We investigate the efficacy of trunk surgery in reducing the external symptoms linked to some diseases of the Esca complex and on the possible role of decayed wood removal on the microbiota in the trunk of Esca complex affected vines
Trunk surgery is a technique applied to reduce leaf stripe symptoms when they occur in vines, showing the whole range of wood symptoms and especially wood decay

Summary

Introduction

Wood diseases are a major threat for modern viticulture, and the diseases included within the Esca complex remain the most worrying in Europe and worldwide [1,2]. Esca complex is currently considered a complex of different diseases and syndromes (characterized by several different symptoms) mostly associated with ascomycetes species, namely vascular pathogens as Phaeomoniella chlamydospora & Mugnai) [3] (Pch), Phaeoacremonium minimum

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