Fungal pathogens associated with rootstock cane necrosis

Project number: US PP 07 2006
Project leader: Fourie, P H
During 2005 and 2006 samples of rootstock cuttings were collected during the period of harvesting and preparation of rootstock cuttings. These samples were examined for any external and internal symptoms. Isolations, from observed internal symptoms, were made onto PDA. Fungi isolated at the highest frequency from these symptoms were Botryosphaeriaceae and Phomopsis spp., with Phaeoacremonium spp. and Phaeomoniella chlamydospora isolated at much lower frequencies. These genera have all been shown to be important grapevine trunk pathogens, infecting pruning wounds and other mechanical wounds, ultimately causing decline and dieback of nursery and mature grapevines. Some isolates, representing Phoma and Acremonium spp., were also isolated, although these are not recognised as grapevine pathogens. Management strategies aimed at preventing wound infection of rootstock canes by above mentioned pathogens are recommended. These include treatment of pruning wounds on mother vines with pruning wound protecting agents, trellising of mother vines to prevent injury of the rootstock canes and careful inspection and selection of canes prior to grafting.