Plant viruses cause significant economic losses in agriculture and may pose biosecurity risks to lucerne production and seed exports. A previously unknown plant rhabdovirus, Alfalfa dwarf virus (ADV), was detected in 2010 infecting commercial lucerne fields in Argentina and Uruguay with 90% to 95% disease incidence, causing < 50% yield loss and significantly reducing seed production. Due to its potential economic impact in Australia, ADV is listed as high risk pathogen.This research aims to protect the Australian lucerne seed and hay industry from this exotic disease. To date there is no evidence of ADV in Australia. Collaborative research in Argentina aims to determine the disease's epidemiology and the genetic diversity of the viruses involved.