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Simulated Intrafield Dispersal of Maize Chlorotic Dwarf Virus by Graminella nigrifrons With a Rubidium Marker. David R. Alverson, Former graduate student, Department of Entomology, University of Georgia, Athens 30602, Present address of senior author: Department of Entomology and Economic Zoology, Clemson University, Clemson, SC 29631; J. N. All(2), and C. W. Kuhn(3). (2)Associate professor, Department of Entomology, University of Georgia, Athens 30602; (3)Professor, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602. Phytopathology 70:734-737. Accepted for publication 22 January 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-734.

Aqueous sprays of rubidium chloride (RbCl) were applied to emergent johnsongrass to simulate an inoculum source of maize chlorotic dwarf virus (MCDV). The properties of plant uptake and translocation of Rb provided a new approach to epidemiological studies since it could be acquired by vectors feeding on the inoculum sources. Analysis of Rb contents in Graminella nigrifrons collected from nearby corn showed a net dispersal rate of simulated MCDV inoculum from johnsongrass into corn of ~15 m/4 days. A preference of tagged G. nigrifrons for a susceptible hybrid also was demonstrated by analysis of Rb; vector dispersal into DeKalb 1214 was significantly greater (P<0.05) than dispersal into Pioneer 3009. MCD incidence and severity were correlated with levels of the simulated inoculum in vectors collected at varying distances from the treated source.

Additional keywords: disease severity index.