Disease Note.

Occurrence of Peach Rosette Mosaic Virus on Grapevine in Southern Ontario. L. W. Stobbs, Agriculture and Agrifood Canada, Pest Management Research Center, Vineland, Box 6000 . J. G. Van Schagen, Agriculture and Agrifood Canada, Pest Management Research Center, Vineland, Box 6000, Ontario, LOR 2E0. Plant Dis. 80:105. Accepted for publication 8 November 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0105C.

Peach rosette mosaic nepovirus (PRMV) in grapevine has been reported only in Michigan. Recently, the virus has been identified in a 60-year-old Concord planting in the Niagara Peninsula, Ontario. Infection was limited to a circular focus of approximately 18 vines distributed in 7 rows, with a high incidence of dead vines proximal to the diseased vines. Low numbers of the vector, Xiphinema revisi (Dalmasso) (4 nematodes per liter of soil) were recovered from soil sampled around the roots of infected vines. Such low Xiphinema populations are not unusual on such heavy clay soils with poor drainage. No Longidorus spp. were present. Virus was not recovered from native weed species growing adjacent to infected vines. Vines infected with PRMV were stunted, with canes being typically short with crooked growth giving vines an umbrella-like appearance. Leaves were asymmetric, puckered, and frequently mottled with flattened petiolar sinuses. Berries were irregular in size and ripened irregularly, resulting in severe berry shelling and yield loss. PRMV was identified by enzyme-linked immunosorbent assay and host range studies. RNA and protein electrophoresis of the isolate revealed two RNA species (2.2 and 2.5 MDa) and a single protein band (57 kDa) consistent with the literature (I). The vineyard will be removed in 1995 and the land fallowed for several years before replanting in grape.