ROYAL BOTANIC GARDENS, KEW. 
BULLETIN 
MISCELLANEOUS INFORMATION. 
VIII— PLANT DISEASES -IV. DISEASES OF BEET 
AND MANGOLD. 
It is a common saying among horticulturists and others that 
long-continued cultivation of a particular species of plant makes 
it more susceptible to disease than is the case with the same kind 
of plant growing in a wild state. As a rule there is no real 
evidence in support of such an opinion. 
Exhaustion of the soil is a favourite explanation of "beet- 
sickness," "clover-sickness," &c, but numerous exhaustive 
analyses of the soil have clearly demonstrated that the essential 
constituents of the soil have not been lacking; and. furthermore, 
the addition of fertilizers has not reduced the diseases alluded to. 
On the other hand, these diseases have been clearly traced to the 
direct action of animal or fungus parasites, and when these were 
removed the disease disappeared. 
The following is an attempt to deal in an intelligible manner 
with some of the most destructive parasites attacking beet and 
mangold, accompanied by a description of the methods that 
experience has proved to be most effectual in checking the 
Beet Canker. 
(Pionnotea beta*; Sacc.) 
This fungus sometimes destroys stored beet and mangold, 
especially if sweating has occurred. Small scattered glairy, dingy 
yellow spots first appear on the surface of the root ; these soon 
spread and run into each other, forming irregularly shaped, 
nodulose, subgelatinous crusts up to one and a half inches across, 
varying in colour from ochraceous to orange. 
Owing to the cells of the beet being disorganised and used up 
by the mycelium of the fungus large cavities are formed, and, 
aided by myriads of bacteria, the root soon becomes watery and 
rotten, at the same time exhaling a very unpleasant odour. 
Adjoining roots are quickly attacked, and if the disease appears 
soon after the beet are stored a large percentage is often lost, 
1375 Wt 4/06 D&S £9 24300 
