436 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



plant originally used for inoculation, and nine leaves of the plant stand- 

 ing by its side, bore large powdery Oidium- patches, frequently on both 

 sides of the leaf. Some of the older mycelial patches were almost 

 crustaceous in consistency, and covered with a dense layer of accumulated 

 conidia. By June 30 nearly every leaf of both plants was virulently 

 infected, and on one plant the very young wood of several of the twigs 

 was covered continuously for a distance of 2-25 cm. with thin mycelial 

 patches bearing conidiophores. 



The disease has, apparently, only recently made its appearance in 

 England, and indeed in Europe, and its history affords an instructive 

 example of the introduction and gradual spread of a fungus disease. 



The first published record, so far as I have been able to discover, is 

 one by Arcangeli (1), who reported the occurrence of the fungus in Italy 

 at Florence in 1899, and at Livorno (in great abundance) in 1900. I have 

 seen examples collected at Padua in 1903, at Naples in 1904, and in the 

 Botanic Gardens at Pisa in 1905. In 1903 H. and P. Sydow (2) recorded 

 it from Gorz, Austria, and specimens have been sent to me collected in 

 the same year in greenhouses at Meran, South Tyrol. In Hungary it has 

 occurred at Fiume. I have received reports of its occurrence in 1904 at 

 Avignon, Alencon, Vernon, and in the neighbourhood of Paris. Thus 

 during the past few years the disease has been appearing in Italy, Austria, 

 Hungary, and France.* 



As regards England, I have seen examples from Bexhill, Newhaven, 

 Portobello near Rottingdean, Folkestone, Brighton, Seaford, Hastings, 

 Woodnesborough near Dover, and from Ringruer, Iford, and Lewes (a few 

 miles inland), on the South Coast ; t from Felixstowe, Sandwich, Rams- 

 gate, and Margate, on the East Coast ; and from Weston-super-Mare on 

 the West Coast. Inland, it has been noticed at a nursery midway between 

 the South Coast and London ; near the South-Eastern Agricultural College, 

 at Wye ; and on bushes in several private gardens at Kew. In many of the 

 localities on the sea-coast the disease has already assumed the characters 

 of an epidemic of such severity as to check the growth of the plants, and 

 even, in those cases where the premature falling of a great number of 

 leaves is caused, to threaten the life of the plant. 



It seems probable, from the absence of any early record of this con- 

 spicuous fungus, that the Oidium has only lately attacked E. japonicus 

 in Europe. On investigating the point I ascertained that the fungus is 

 well known in Japan, the native home of E. japonicus. Prof. Shotaro 

 Hori, of the Central Agricultural Experiment Station, Nishigahara, Tokio, 

 has kindly furnished me with the following note on the occurrence of the 

 Oidium in Japan : — " E. japonicus, either wild or when planted in gardens, 

 is very susceptible to the attacks of a white mildew, during warm seasons, 

 throughout Japan. As far as my observations go, the mildew appears on 

 the leaves as early as the beginning of April and continues its growth 

 until the autumn, but I have never seen the formation of perithecia. 

 I have sometimes found, in shady places, the Eiwnymus entirely covered 

 with white mildew, but the fungus does not seem to affect much the 



* I have now received, from Professor Ed. Fischer, examples of the disease from 

 Switzerland (Canton Berne, June 1904). 



f It has been reported by a gardener as occurring in the Isle of Wight. 



