Factors Involved on Tiger-Stripe Foliar Symptom Expression of Esca of Grapevine.

Francesco Calzarano,Mirella Bellocci,Giancarlo Pagnani,Giuseppe Cillo,Elisa Giorgia Metruccio,Michele Pisante,Stefano Di Marco

doi:10.3390/plants10061041

Abstract

Esca of grapevine causes yield losses correlated with incidence and severity symptom expression. Factors associated with leaf symptom mechanisms are yet to be fully clarified. Therefore, in 2019 and 2020, macro and microelement analyses and leaf reflectance measurements were carried out on leaves at different growth stages in a vineyard located in Abruzzo, central Italy. Surveys were carried out on leaves of both never leaf-symptomatic vines and different categories of diseased vine shoots. Never leaf-symptomatic and diseased vines were also treated with a fertilizer mixture that proved to be able to limit the symptom expression. Results showed that untreated asymptomatic diseased vines had high calcium contents for most of the vegetative season. On the contrary, treated asymptomatic diseased vines showed higher contents of calcium, magnesium, and sodium, at berries pea-sized, before the onset of symptoms. These vines had better physiological efficiency showing higher water index (WI), normalized difference vegetation index (NDVI), and green normalized difference vegetation index (GNDVI) values, compared to untreated asymptomatic vines, at fruit set. Results confirmed the strong response of the plant to symptom expression development and the possibility of limiting this response with calcium and magnesium applications carried out before the symptom onset.

Highlights

Esca of grapevine is a complex, destructive and widely spread disease
Leaf Fertilizer Applications and Foliar Symptom Surveys. Both years of survey on incidence and severity of foliar symptoms in the Controguerra vineyard confirmed the dynamics of symptom expression, characterized by a remarkable increasing from the berries developing color stage
Dynamics of macro and microelements and vegetation indices highlighted in this study, as for the dynamics of phytoalexins discussed in our recent studies, suggested the role of calcium and magnesium in tiger-stripe foliar symptoms expression

Summary

Introduction

Esca of grapevine is a complex, destructive and widely spread disease. The disease includes the involvement of several microorganisms producing different types of wood deterioration at different age of the plant, from nursery to ageing vineyards. The disease has been commonly associated with tracheomycotic pathogens as Phaeomoniella chlamydospora, Phaeoacremonium minimum (or another species of Phaeoacremonium), and with the basidiomycete Fomitiporia mediterranea, or other species recently isolated in United States [1,2,3,4,5]. The fourth disease of Esca complex, was mainly caused by Fomitiporia mediterranea [7]. The fifth disease, named as Esca proper, was considered the concomitant occurrence of tracheomycotic and white rot pathogens and relative wood alterations in the same plant, traditionally reported as “Esca of grapevine”

Objectives

Results

Discussion

Conclusion