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Statistical Analysis of Some Dilution Assays of Maize Dwarf Mosaic Virus. D. Jowett, Associate Professor, Department of Statistics, Iowa State University, Ames, Iowa 50010, Current address: CES, University of Wisconsin, Green Bay 54302; R. E. Ford(2), and J. C. Tu(3). (2)(3)Professor and Postdoctoral Research Associate, Department of Botany and Plant Pathology, Iowa State University, Ames, Iowa 50010, Current address(3), Electron Microscope Laboratory, Biological Sciences, University of Alberta, Canada. Phytopathology 62:366-368. Accepted for publication 25 October 1971. DOI: 10.1094/Phyto-62-366.

An established statistical model, based upon the assumption that the number of effective virus particles in an aliquant of infective sap follows a Poisson distribution, is applied to previously published dilution assays of maize dwarf mosaic virus. The model gives good results for the number of virus particles when sap from infected plants is diluted with sap from healthy plants, but not after dilution with water or phosphate buffer unless data from higher concentrations are omitted. This is apparently due to the presence of inhibitors in the original infective sap, which become so dilute as to be insignificant at dilutions of 100 times or more. The inhibitors are partly, but not totally, destroyed when the plant sap used for dilution is heated or clarified.