The Contribution of Imperfections in Nursery Stock to the Decline of Young Vines in California

James A. Stamp


‘Petri disease’, as defined at the 2nd International Workshop on Grapevine Trunk Diseases (Esca and
Grapevine Declines, September 14–15 2001, Lisbon, Portugal), is a condition associated worldwide with the decline
of young vines contaminated by Phaeoacremonium and/or Phaeomoniella pathogens. Vines exhibit stunted development
with vascular tissues characteristically exuding darkened gums when sectioned transversally. ‘Young Vine
Decline’ (YVD), historically including the condition now known as Petri disease, is a term still used widely in California
to describe unexpectedly poor performance of young vines exhibiting symptoms that include those associated
with Petri disease. Examination of more than eight hundred thousand dormant nursery vines as well as new and
established declining vineyards demonstrated that nursery stock defects and mechanical and biotic vineyard stresses
were frequently associated with YVD in California. Rootstock shaft lesions and weak roots were most commonly
associated with YVD in very young vineyards, while root system contamination by nematodes and fungal pathogens
was frequently associated with YVD in older vineyards.

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