DISEASES DUE TO BACTERIA 139 
scraped off, all decayed parts cut out, and the corms 
well scrubbed with water, using a fairly strong brush. 
The prepared corms are next steeped, taking care to 
keep as much of the foliage out of the liquid as possible, 
in a 2 per cent solution of formaldehyde (1 part 40 per 
cent formaldehyde in 49 parts of water) for four hours. 
After this time they are removed and immediately potted 
up in disease-free soil and sterilized pots. 
The treated corms rapidly produce a supply of clean, 
white roots, and have every appearance of health, while 
the untreated controls quickly show all the symptoms of 
the disease. This method has been tested on a large 
scale at a commercial nursery, and so far the plants 
have remained healthy. 
_ The chance of secondary infection in nurseries where 
the disease has been epidemic is exceedingly great, and 
special care must be taken to prevent it. Disease-free 
soil and pots are essential, and the treated corms must 
not be replaced in infected houses unless these have been 
sterilized previously. Should the well from which the 
water supply is drawn be a shallow surface one with 
faulty brickwork, there is every possibility that it has 
been infected by surface drainage. Expert advice should 
be obtained on this point, for a clean water supply is 
imperative. 
