Preliminary histological observations on grapevine affected by esca disease

Esca is a destructive disease of the woody tissues of grapevine (Vitis vinifera L.) and due to the complexity of disease many aspects of host-pathogen interactions are not clearly understood. The histological characteristics of esca symptomatic petioles and internodes, collected from Cabernet Sauvignon and Sangiovese grapevine were studied. The tissues were fixed in FAA, dehydrated and embedded in Histoplast. To identify the lignified cell walls the sections were stained by Crystal violet and Erythrosin B and observed using an optical microscope. The main feature of tissues infected by esca disease was the minor lignification of vascular tissues, which was observed in petiole tissues before appearance of esca symptoms. The opportunity to utilize the histological examination of tissues as a method for the early detection of esca infections is hypothesized for the future application.