Winegrape cultivars (Vitis vinifera) vary in susceptibility to the grapevine trunk pathogens Eutypa lata and Diplodia seriata.

Background and Aims: Eutypa and Botryosphaeria dieback are diseases that affect vineyards worldwide, reducing productivity and longevity. The ability of the causal pathogens Eutypa lata and Diplodia seriata to colonise grapevine canes was investigated in the search for resistance or tolerance to trunk diseases. Methods and Results: Visual assessments of 174 winegrape cultivars (Vitis vinifera) in a mature germplasm collection in the Barossa Valley in South Australia revealed substantial variation (0–98%) in severity of foliar symptoms and dieback. A selection of 18 cultivars representing those without symptoms or low (<10%) severity was compared with the susceptible cultivars Shiraz and Sauvignon Blanc. Inoculation of canes in situ in the vineyard and detached canes in the greenhouse, confirmed variability among cultivars for the extent of pathogen colonisation. Conclusions: Cultivars varied in susceptibility to colonisation by E. lata and D. seriata, with some differences between the two pathogens in terms of the ranking of cultivars. Muscadelle was most resistant to colonisation by both pathogens, and Sauvignonasse was the most susceptible. Significance of the Study: Knowledge of cultivar susceptibility to grapevine trunk diseases will assist in prioritisation of disease management strategies. Identification of cultivars with resistance could inform selection of planting material and may lead to improved breeding programs in the future. [ABSTRACT FROM AUTHOR]