Abstract:
Graft and dodder transmission studies of the witches' broom virus disease of lucerne extended the known host range of the disease to eight new host species. Two selected lucerne plants obtained in the field were found to be infected with distinct strains of the virus. On 14 host species (including tomato and lucerne), one of the two strains (B) produced symptoms that were indistinguishable from those of big bud of tomato. The other strain (A) caused less severe proliferation and did not cause greening of floral parts. The diseases resulting from infection with the strain B witches' broom of lucerne and the big bud virus of tomato are considered to be identical. Symptoms of witches' broom of lucerne in Australia are compared with symptoms of witches' broom of lucerne in America, and with those of some other yellows virus diseases.