ROYAL GARDENS, KEW. 
DULLETIN 
MISCELLANEOUS. INFORMATION. 
No. m p : DECEMBER. [1898. 
DCXXXI.—GUMMOSIS OF PRUNUS JAPONICA, 
THUNB. 
(With Plate.) 
During the past two redi a considerable number of joven 
of the beautiful flowering shrub, Prunus japonica, Thunb., 
growing in Kew Garden iud have been killed or much disfigured by 
a parasitic fungus belonging to the genus Cladosporium. 
The disease is first indicated by the appearance of tear-like 
drops of almost colourless gum on the branches. These drops are 
sometimes solitary, in other rita numerous and more or less 
crowded, 
The ae eee to increase in size for some time, often 
forming ma arying in size from a marble to that of a 
walnut, and enr two or more originally distinct drops coalesce 
the resulting mass usually becomes irregularly nodulose and 
conto der 
ng damp or rainy weather the masses of gum are quite soft 
and gelatinous with just sufficient consistency to hold eei 
or sometimes during a heavy rain drip away by de egrees. In very 
dry, warm weather the mass shrinks very considerably in size and 
becomes horny, expanding again when moistened. 
As previously stated the mass of guin is almost colourless at 
first, becoming steel-grey as it increases in size, e finally black. 
The black colour is however confined to a surface layer, the 
central portion remaining colourless. This is aa evident on 
cutting through a mass that has been hardened in spirit. 
In the end these outflows of gum are always washed to the 
ground by rain, where they RIRS dissolve and disappear 
1242—1375—12/98 Wt92 D&S 29 
