Subterranean clover stunt, a virus disease of pasture legumes

A study has been made of a recently recognized virus disease, subterranean clover stunt. Field observations of its occurrence, distribution, and symptoms, and experimental data on insect transmission are recorded. Attempts to transmit the disease by mechanical means and by leafhoppers were unsuccessful. It was transmitted by two species of aphids, efficiently by Aphis craccivora Koch and less efficiently by Myzus persicae (Sulz.), but not by four other species of aphids tested. The virus was transmitted to a series of indicator plants by aphids and, since it carried over a moult of A. cruccivora, it belongs to the "persistent" type. The host range covers a wide variety of legumes, including some subtropical species. The means by which the disease is carried over from season to season was not determined but the virus probably persists in summer-growing annual and perennial legumes.