Field Screening of Grape Rootstock Selections for Resistance to Fanleaf Degeneration. M. A. WALKER, Department of Viticulture and Enology, University of California, Davis 95616-8749. J. A. WOLPERT, Department of Viticulture and Enology, University of California, Davis 95616-8749, and E. WEBER, University of California Cooperative Extension, Napa 94559-2597. Plant Dis. 78:134-136. Accepted for publication 27 September 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0134.

Fifty-five grape rootstock selections produced by L. A. Lider, nine Vitis vinifera X Muscadinia rotundifolia (VR) hybrids produced by H. P. Olmo (both of the University of California, Davis), and three fanleaf degeneration-susceptible grape rootstocks were planted in 1979 in a site in the Napa Valley, California, known to be infested with grapevine fanleaf virus (GFLV) and viruliferous Xiphinema index. All of these rootstock selections were field-budded with V. vinifera cv. Cabernet Sauvignon. The site was chosen because of the relatively uniform distribution of virus and vector. Shoot tips from the scions were first assessed for the presence of GFLV in 1981 with enzyme-linked immunosorbent assay (ELISA). Yearly ELISA assessments continued through 1991. GFLV was detected in scions on all rootstocks, but not for 10 yr in scions on VR O39-I6.