Volume III JANUARY, 1917 Nos. 2 and 3 



A BACTERIAL SPOT OF CITRU8. 



By ETHEL M. D0IDC4E, D.Sc, F.L.S., 

 Mycologist, Union Department of Agriculture. 



(With Plates III— XIII). 



In October 1914, toward the close of the Citrus season, a grower in 

 the Western Province submitted for examination some lemons badly 

 disfigured by dark-coloured sunken spots ; he stated that he had first 

 noticed this blemish two seasons back, but that it was rapidly on the 

 increase ; as much as 30 per cent, of his lemons were affected, and the 

 trouble was spreading to the Washington Navel oranges. 



No fungus myceUum could be found in the discoloured tissues, but 

 there were pockets of disintegrated cells filled with innumerable bacteria. 

 A pure culture was obtained at once from these tissues, and a few suc- 

 cessful inoculations carried out. It was too late in the season however 

 to enter on a complete investigation of the trouble, and further work 

 in connection with it had to be deferred until the present year, when 

 the matter was taken up as soon as favourable weather conditions 

 started the spread of infection to the new crop of fruit. 



A detailed study of the causal organism has now been carried out, 

 and a survey made of orchards in the infected area with a view to pre- 

 venting if possible a further spread of infection. 



LiTEEATURE. 



Two bacterial diseases of citrus have been described, both occurring 

 in America; the so-called "citrus canker" of Florida need not be more 

 than mentioned here; the macroscopic characters of the "canker" 

 are entirely different from those of the spot under consideration, it is 

 characterised by a prohferation and subsequent suberisation of the 

 cells of the affected tissues (4). 



A much more closely related trouble however is reported from 

 the lemon growing sections of Southern California (O) ; it has been 



Ann. BioL in 4 



