Biological Characterization of Australian Isolates of Citrus Tristeza Virus and Separation of Subisolates by Single Aphid Transmissions. Patricia Broadbent, Biological and Chemical Research Institute, NSW Agriculture, PMB 10, Rydalmere, N.S.W., 2116, Australia. R. H. Brlansky, University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850-2299; and J. Indsto, Biological and Chemical Research Institute, NSW Agriculture, PMB 10, Rydalmere, N.S.W., 2116, Australia. Plant Dis 80:329. Accepted for publication 12 December 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0329.

Citrus tristeza virus in Australian citrus is a complex of isolates that differ in biological properties and rates of aphid transmission. Biological characterization of isolates on citrus indicators produced a range of symptoms varying in type and severity depending on the field host and geographical location. Single aphid transmissions with the vector Toxoplera citricida separated some of these subisolates based on biological indexing on three citrus indicators and the numbers of inclusion bodies produced. Inclusion numbers produced in Citrus aurantiifolia were positively related to isolate and subisolate severity in that host