Esca in young and mature vineyards, and molecular diagnosis of the associated fungi.

Esca is one of the most important grapevine trunk diseases, and it can induce severe declines. In the past, the disease occurred mostly with mature vines, but today it is also present in young vineyards. The aim of this study was to investigate the incidence of esca in young (less than 7 years old) and mature (more than 11 years old) vineyards with cvs. Montepulciano, Sangiovese, Verdicchio and Passerina located in the main viticultural areas of the Marche Region, central-eastern Italy. The average incidence of diseased plants was higher in mature (32.58%) than young (5.21%) vineyards, and Verdicchio and Passerina appeared to be the most sensitive among the cultivars considered, followed by Sangiovese and Montepulciano. The analysis of the spatial spread of esca carried out in two mature vineyards with cv. Verdicchio and a young vineyard with cv. Sangiovese showed a fluctuation in the numbers of infected plants over the three years of observation. The fungi associated with symptomatic plants were detected by classical and, in part, molecular tools. Isolation on agar media yielded colonies of Phaeomoniella chlamydospora (Pch), Botryosphaeria spp. (Bot), Fomitiporia mediterranea (Fomed) and, sporadically, Phaeoacremonium aleophilum (Pal). In samples from young plants, Bot and Pch were recurrent, while Pch and Fomed were found with mature vines and old rootstocks. Molecular detection with specific primer pairs for Pch, Pal and B. dothidea confirmed the data obtained using classical tools, and in some cases it was more sensitive. This study thus provides a further contribution as to the presence of different causal agents in the expression of esca symptoms, and it confirms the importance of molecular tools for the sensitive detection of associated pathogens, which can also be present in propagative materials.