A VIRUS-LIKE DISEASE OF STRAWBERRY-TREE (ARBUTUS UNEDO L.)

The diseased trees display brownish, often concentric, rings on the leaves; leaf dwarfing; bud drop; rosetted tuft of leaves at the end of the twigs; brown spots on the fruits and a slow decline.

Graft transmissibility of the symptoms was proved by inserting bark of infected trees underneath the bark of rooted scions taken from apparently healthy strawberry-trees located in an area where the disease was not present. The first symptoms appeared on the inoculated plants a year later.

Attempts to mechanically transmit viruses from diseased trees to herbaceous plants, were attempted for 2 years by macerating leaves, flowers and fruits with different extractants have been unsuccessful.

Examination of diseased leaf tissue by electron microscopy has revealed in several cells virus-like particles.