Fungi associated with grapevine trunk diseases in nursery-produced Vitis vinifera plants

Abstract

Grapevine trunk diseases (GTDs) are one of the most important groups of fungal diseases affecting grapevine plants worldwide. One of the main causes of GTDs infection occur during nursery plant production processes. The phytosanitary status was determined for 150 young grapevine plants (two varieties grafted onto different rootstocks) that were produced in three European nurseries. Some plants were analyzed upon submission, while others were assessed after up to 12 months growth in a greenhouse. Fungal species associated with GTDs were identified and characterized from the scions, graft unions, rootstocks, or roots. A total of 449 fungal isolates associated with GTDs were obtained, and 20 species were identified by morphological characteristics and DNA analyses. Five species were involved in Botryosphaeria dieback, six in black foot disease, six in Diaporthe dieback, and three in Petri disease. Incidence of GTDs on grapevine plants was between 81 and 100%, with different diseases varying between rootstocks and grapevine varieties. Isolates of other fungal genera not involved in the GTD complex were also detected, including Colletotrichum, Fusarium, and Rhizoctonia. The high presence of GTDs during nursery production of grapevine plants raises the need to implement effective control methods that could prevent the spread of these diseases to vineyards.