Grafts on the hybrid seedling controls gave poor results. Discussion Ink disease, caused by Phytophthora spp. The impact of the disease has been particularly severe in the traditional 'Marrone' orchards of Cuneo province, where historically these valuable chestnut cultivars were grown on rich alluvial soils near the valley floors. Ink disease has nearly eliminated the cultivar 'Marrone di Chiusa Pesio' from its native area. There is an urgent need to propagate this variety onto Phytophthora -resistant rootstocks to ensure its survival as a commercial cultivar.
Good compatibility is indicated by a well healed union, without swelling, of uniform diameter.
These two cultivars are now widely grown in northern Italy and many plants grafted onto their seedlings are commercially available. As a clonal rootstock, CA07 is very promising and worthy of further trial in the Cuneo area. And, even though the percent take with 'Marrone di Chiusa Pesio' on CA07 was not very high, the quality of the graft union appeared near perfect. The rootstock CA15 is also deserving of further study. The grafted plants from this study will be planted in an orchard setting for future observations on long-term compatibility, vigor, and yield.