Screening of Spanish Vitis vinifera germplasm for resistance to Phaeomoniella chlamydospora

Esca and leaf stripe diseases are two of the most destructive grapevine trunk diseases which are caused by a complex of fungal species, being the Ascomycete Phaeomoniella chlamydospora the most frequently isolated species from affected vines. To date, no curative measures are known for control these diseases; therefore, planting disease-resistant cultivars is a time-tested and sustainable approach for disease management. The aim of this study was to identify sources of resistance to P. chlamydospora among minority and commercial grapevine germplasm collections in Spain. For this purpose, 15 and 38 cultivars from the ITACyL and the EVEGA collections, respectively, were selected based on the visual assessment of symptom expression in standing vines over the last 3 years, and inoculated with P. chlamydospora in a detached cutting assay under greenhouse conditions over two consecutive years. Seven months after inoculation, cuttings were collected and inspected for lesion length. The severity of internal wood symptoms caused by P. chlamydospora varied considerably amongst the cultivars. No foliar symptoms were observed during the experiment. All cultivars were susceptible to fungal necrotic infection, indicating that there is no evidence of qualitative resistance to this Ascomycete fungus.