Current UC Viticulture Research

American Vineyard Foundation

Clone FPS 29, the Niebaum-Coppola clone, was from old plantings near the Niebaum-Coppola winery which provided premium quality grapes. Clone FPS 30, the Disney Silverado clone, was from an old vineyard off Silverado trail believed to be planted with the See clone of Cabernet. Clone 31, the Mondavi clone, was collected from 50-year old vines in the To-Kalon vineyard. All three original virus-infected parent selections were infected with Grapevine leafroll associated virus -3 (GLRaV-3), Grapevine virus B (GVB), and Grapevine fleck virus (GFkV). Each clone was treated by meristem shoot tip culture to eliminate virus (Golino et al., 2001). The trial was planted in a randomized vineyard block at the UC Oakville Station in Napa Valley.

Brix was significantly lower, by an average –4.0, in all three original virus-infected sources (VIS) compared to their treated progeny (Figure 1).

Virus effects on yield, pruning weight, and titratable acidity varied with clone. Two original selections, had significantly lower yield than their treated progeny. VIS 29 had a 45% yield reduction compared to FPS 29; VIS 31 had a 30% yield reduction compared to FPS 31. Also, yield between healthy clones was significantly different; yield of FPS 29 and FPS 30 was almost double that of FPS 31 (3.1, 3.0, 1.7 kg/vine, respectively (Figure 2).

Titratable acidity was increased in the virus-infected selection in one pair, VIS31/FPS31, but not the other two (Figure 3). This may be a result of clonal difference in virus response or strain difference between viruses.

The virus-infected selections were removed due to concern that leafroll disease might spread to adjacent clones and trials.

Although all three Cabernet Sauvignon selections were infected with the same virus species (GLRaV-3, GVB, and GFkV), they came from diverse sources. There may be strain differences between those species affecting the severity of symptoms. Different strains of each species of GLRaV would be expected by plant virologists to demonstrate variation in symptom severity. This data provides some evidence for that hypothesis.

Figure 1. Fruit sugar content (Brix)

Figure 2. Yield for virus-infected selections and clones

California Observation of Leafroll Effects and Field Spread: Dr. Deborah Golino, Cooperative Extension Specialist, Department of Plant Pathology, UC Davis, discusses her observations of leafroll effects and field spread over the last 15 years in this videotaped presentation.

Michael Anderson
Jason Benz
Deborah Golino
Vicki Klaassen
Adib Rowhani
Susan Sim
James Wolpert

Golino, D. A. 1992. The Davis Grapevine Virus Collection. American Journal of Enology and Viticulture 43(2):200-205. Abstract

Golino, D.A., Sim, S.T., Bereczky, J.  and  Rowhani, A. 2001. The Use of Shoot Tip Culture in Foundation Plant Materials Service Programs. Combined Proceedings of the International Plant Propagators Society, Volume 50:568-573.

Osman, F., Leutenegger C., Golino D. and Rowhani, A. 2008. Comparison of low-density arrays, RT-PCR and real-time TaqMan RT-PCR in detection of grapevine viruses. J Virol Methods149(2):292-9. Epub 2008 Mar 10.

Rowhani, A., 1992. Use of (ab)2 antibody fragment in ELISA for detection of grapevine viruses. Am. J. Enol. Vitic. 43:38–40. Abstract

Rowhani, A., Biardi, L., Johnson, R., Saldarelli, P., Zhang, Y.P., Chin, J., Green, M., 2000. Simplified sample preparation method and one-tube RT-PCR for grapevine viruses. In: Proceedings of XIII International Council for the Study of Viruses and Virus-Like Diseases of the Grapevine, Adelaide 2000,p. 82.