Susceptibility of American Grapevine Scion Cultivars and French Hybrid Rootstock and Scion Cultivars to Infection by Peach Rosette Mosaic Nepovirus. D. C. RAMSDELL, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. J. M. GILLETT, and G. W. BIRD, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Plant Dis. 79:154-157. Accepted for publication 17 October 1994. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0154.

Peach rosette mosaic virus (PRMV), a nepovirus prevalent in Michigan, causes severe crop loss and death to Concord grapevine cultivars. Because of the high cost of soil fumigation, combined with the removal of most soil fumigants from the market, three types of grapevine cultivars (American scion cvs. Concord, Delaware and Niagara; French-American hybrid rootstock cvs. Couderc 1202, C. 1616, Teleki 5A, and Teleki 5C; French-American hybrid scion cvs. Chancellor, Foch, Seyval, and Vignoles) were tested for resistance to PRMV. In 1986, 44 vines of each cultivar were planted into a field that had contained mature, uniformly PRMV-infected Concord vines and a uniform population distribution of the dagger nematode vector (Xipinema americanum). From 1988-1991 each vine was annually tested for PRMV infection by enzyme-linked ammunosorbent assay in the spring and summer. By 1991, the final year of testing, PRMV was detected in less than 5% of the vines of Chancellor and Couderc 1616, 7% of the vines of Couderc 1202 and Foch, 18.2% of the vines of Niagara and Delaware, 20% of the vines of Teleki 5C, and 50% or more of the vines of Vignoles, Teleki 5A, and Concord. Seyval remained uninfected for the duration of the experiment. The greatest reduction in yield and growth (up to 40 and 60%, respectively) was in Concord. Chancellor, Couderc 1202, Couderc 1616, Foch, Teleki 5A, and Vignoles also showed reduced yield, growth, or both, when PRMV-infected and healthy vines were compared.