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Dodder Transmission of Tomato Ringspot Virus. R. A. Welliver, Pennsylvania Department of Agriculture, Harrisburg 17110. J. M. Halbrendt, The Pennsylvania State University Fruit Research Laboratory Biglerville 17307. Plant Dis. 76:642. Accepted for publication 15 January 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0642C.

Tomato ringspot virus (TmRSV), causal agent of Prunus stem pitting, is transmitted by dagger nematodes (Xiphinema spp.) to fruit trees in the northeastern United States. Because weed reservoirs of TmRSV have been identified as important factors in virus spread (1), Cuscuta gronovii Willd. ex Roem. & Schult., a common dodder species in Pennsylvania, was tested for its ability to vector TmRSV between weed hosts. C. gronovii seed was collected from flowering strands established on Chenopodium album L. in a Pennsylvania peach orchard. The dodder seed was cogerminated with Chenopodium quinoa Willd. in the greenhouse. Dodder seedlings tested negative for TmRSV and tobacco ringspot virus by enzyme-linked immunosorbent assay (ELISA). The dodder was first trained to TmRSV infected Chenopodium quinoa and, when established, was trained back to healthy Chenopodium quinoa or Cucumis sativus L. Healthy plants were shaded for 1 wk after contact with dodder. TmRSV infection was confirmed by systemic symptom development and by ELISA in 21 of 26 plants. Our results indicate that dodder could have a role in local epidemiology of Prunus stem pitting by facilitating TmRSV transmission among weed species.

Reference: (1) C. A. Powell et aI. Plant Dis. 68:242, 1984.