Identification of Sugarcane Mosaic Virus Strain H Isolate in Commercial Grain Sorghum. Laura M. Giorda, Graduate Student, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843. R. W. Toler, Professor, Department of Plant Pathology and Microbiology, and F. R. Miller, Professor, Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843. Plant Dis. 70:624-628. Accepted for publication 21 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-624.

A virus isolated from grain sorghum resistant to maize dwarf mosaic virus (MDMV) was examined and identified as an isolate of sugarcane mosaic virus strain H (SCMV-H) on the basis of host range, particle morphology, and serological relationships. The host range was similar to that of SCMV-H except for differences in the severity of reactions of three sorghum accessions. The virus was serologically related to SCMV-I and SCMV-H. No serological relationship was detected among strains A, B, and D of SCMV or among strains A, B, D, E, and F of MDMV. The average length of particles of the sorghum isolate (SI) was 706 nm and did not differ from that of SCMV-H (708 nm). The SI was more closely serologically related to SCMV-H than to other SCMV and MDMV strains. PAG3387 and DR1125 (sorghum accessions) were differential hosts for the SI; they are resistant to MDMV-A and susceptible to the SI of SCMV-H and the type isolate SCMV-H. Four sorghum accessions were immune from the SI of SCMV-H. These were QL3-Texas, QL3-India, SC0097-14E, and QL11. SCMV-H was confirmed as a pathogen of commercial grain sorghum.