Bulletin 13T. /\uguist, \<^O^U 



Ontario Agricultural College and Experimental Farm 



A Bacterial Disease of Cauliflower (Brassica oleracea) 



and Allied Plants. 



By F. C. HARRISON, Professor of Bacteriology. 



In the summer of 1901, a market gardener, in the vicinity of 

 Guelph, who made a specialty of growing cauliflowers, complained of 

 a disease which was afl'ecting his plants. Shortly afterwards the 

 cauliflowers in the garden department of the College were also found 

 to be infected, while further investigation in the neighborhood showed 

 that a disease, or rot, of cauliflowers, cabbages and white turnips was 

 quite general and had done considerable damage to these crops. 



In the case of the market gardener referred to, more than half 

 of his plants were aflected, while in the College garden, about 5 per 

 cent, of the plants were diseased. 



Some 40 varieties of white turnips were tested on the trial 

 grounds at Guelph, and most of them were more or less aflected with 

 the rot, the percentage of decayed roots varying with the varie'y, in 

 some cases reaching as high as 64 per cent. The few farmers in the 

 Province, who experimented with the varieties of white turnips that 

 were sent out from this Experiment Station, reported a considerable 

 amount of soft rot. 



Later in the same summer I visited a number of farms in the 

 vicinity of Woodstock, and found a varying percentage of white 

 turnips rotting in the fields, although the Swede turnips were not 

 aflected, and from conversation with a number of farmers who visited 

 us during the past season, I also gathered that wherever white turnips 

 were grown there was considerable rot during the season of 1901. 



Pathogenesis, 



In order to positively demonstrate that the organism isolated 

 from the cauliflower and turnip was the cause of the rotting, the 

 usual requirements were worked out. 



1. Constant association of the Bacillus tuith the Disease (named 

 Bacillus oleraceae and subsequently described). 



The same bacillus was isolated from diseased cauliflowers from 

 the vicinity of Guelph, and from the garden department of the 



