The 2017/18 testing, grafting and production season saw the first of Grapevine leafroll-associated virus 3 (GLRaV-3) and Grapevine Pinot Gris Virus (GPGV) in protocol 2010 certified stock.  GPGV is vectored by the fairly ubiquitous Erineum mite, which results in the development of characteristic galls on the upper leaf blade.  GLRaV-3 is mealybug-vectored and continues to have perhaps the greatest impact on new vineyards planted with contaminated stock.  Many nurseries are now using Protocol 2010 CDFA-certified materials in a greater proportion of delivered stock, but the most popular rootstocks and scion clones may still only be available as Classic CDFA-certified-or even as non-certified materials-propagated from commercial vineyards planted to certified stock.

Roostock and scion selections that are in high demand and therefore more likely to sell out early-and often only be available as non-certified materials-include Sauvignon Blanc FPS 01, Chardonnay FPS 04, VR O39-16 and 1103P.  It is important to read the grapevine purchase sales contract or, if uncertain, seek clarification from the nursery regarding the source of plant material components.

Read the full article by Alan Wei Ph.D. and James A. Stamp Ph.D.

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