NCPN Grapes
NCPN Grapes
NCPN Grapes
University of California
NCPN Grapes

Grape Viruses

Over 80 graft-transmissible agents (viruses, virus-like agents and phytoplasmas) are known to occur in grapes. Three of the more important viruses in the United States, listed here, can greatly reduce yield and negatively affect fruit and wine quality, by reducing sugar content, affecting fruit color and increasing fruit juice acidity.  The extent of the effects is dependent on many factors, including cultivar, rootstock, environment, and cultural practices.


Grapevine leafroll associated viruses (GLRaVs) are members of the family Closteroviridae; most of them are vectored by mealybugs and soft scales.
Interveinal reddening and green veins are symptomatic of leafroll viruses.
Grapevine fanleaf virus (GFLV) is a member of the family Secoviridae and is vectored by the dagger nematode Xiphinema index.
Chrome mosaic is one of the symptoms of fanleaf virus.
Grapevine red blotch virus (GRBV) is a member of the family Geminiviridae and transmitted by the three-cornered alfalfa hopper, Spissistilus festinus (Hemiptera: Membracidae) in experimental conditions.
Red blotch symptoms in Merlot (photo credit R. Smith UCANR)

NCPN LogoThe National Clean Plant Network (NCPN) is a voluntary association of specialty crop networks that have joined to promote the use of pathogen-tested, healthy plant material for food crops in the United States. The NCPN operates under the auspices of three agencies within the United States Department of Agriculture - Animal and Plant Health Inspection Service (APHIS), Agricultural Research Service (ARS) and National Institute of Food and Agriculture (NIFA).



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