Abstract
As has been previously reported, the dwarf disease of mulberry tree could not be transmitted when diseased scions were grafted on healthy stocks, (moreover, the diseased scions were found to recover), but it was transmitted when healthy scions were crown grafted on diseased stocks. It was attempted to obtain further information on the nature of recovery of the diseased scions mentioned above.
When diseased cuttings were obtained during a period from September to November and grown September to December, they all developed shoots showing typical symptoms, whereas the coresponding diseased cuttings grown in January showed a tendency to recover; those grown in February to May nearly or completely recovered, producing new healthy shoots. Cuttings obtained in January and February also developed healthy shoots when they were grown in February and April, while diseased cuttings which were cut and grown in May after they had shown symptoms, all produced diseased shoots.
It is suggested that the virus of this disease is either inactivated or decreased in the affected shoots during winter.
