A VIRUS DISEASE OF DIEFFENBACHIA 'EXOTICA'

From Dieffenbachia 'Exotica' plants a virus with flexuous rod-shaped particles was transmitted to seedlings of Philodendron selloum, where growth stunting, streaking and malformation of the leaves were induced. Measuring 205 particles in P. selloum gave a peak length at 807 nm. Back inoculation to healthy Dieffenbachia 'Exotica' caused growth stunting, sometimes tip necrosis, malformation and brown necrotic edges of the leaves. The normal "mosaic" pattern sometimes changed to a dirty yellowish colour. Symptoms in Dieffenbachia were most clearly expressed in the autumn, in the other seasons the symptoms faded and new growth looked normal. In the artificially inoculated Dieffenbachia the flexuous rods could be demonstrated. Upon back inoculation to P. selloum the same symptoms developed and flexuous rods could be demonstrated. It is concluded that the Dieffenbachia disease concerned is caused by a virus belonging to the potato virus Y group.