Characterization of a Blackeye Cowpea Mosaic Virus Strain from South Carolina. J. F. Murphy, Former Graduate Assistant, Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29634-0377. O. W. Barnett, and W. Witcher. Professors, Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29634-0377. Plant Dis. 71:243-248. Accepted for publication 22 October 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0243.

A blackeye cowpea mosaic virus isolate (BlCMV-NR) recovered from a cowpea plant grown in Greenville County, South Carolina, differed from BlCMV-FS (a Florida isolate like the type strain) in its biological properties (symptomatology and host range) but not in its physiochemical properties. On cowpea, BlCMV-NR induced reddish necrotic ringspots on inoculated leaves that spread into a network of veinal necrosis. A systemic mosaic developed with distortion of leaflets and stunting of the plant. BlCMV-NR but not BlCMV-FS infected Ocimum basilicum, Phaseolus lunatus ‘Henderson-Bush,’ P. vulgaris ‘Bountiful,’ and Vicia faba. Both BlCMV isolates were transmitted in a nonpersistent manner by the aphid Macrosiphum euphorbiae. Purified preparations of BlCMV-NR averaged 9.8 mg/100 g of tissue, whereas yields of BlCMV-FS averaged 4.9 mg/ 100 g of tissue. The estimated molecular weight of protein structural units of both BlCMV isolates were similar on 5 and 8% acrylamide gels, and the RNA molecular weight of each isolate averaged 2.9 × 10⁶. The two BlCMV isolates induced similar cytoplasmic inclusions with pinwheels and scrolls. The isolates were indistinguishable by serology tests and were very similar by cDNA hybridization tests.