26 DISEASES OF CULTIVATED PLANTS 



in the field. More than this, I have proved, on more than one 

 occasion, that a fungus disease which has proved destructive 

 to a crop has originated in the first instance from spores 

 produced on weeds growing on the borders of the field. 

 A celebrated professor of agriculture, hailing from one of 

 our universities, has pronounced the above statement to be 

 a mycological myth, adding as a rider, that it was impractic- 

 able to keep headlands, etc., clear of weeds. As to whether 

 it is practicable to keep headlands clear, or even as to 



FIG. i. Leaf mould infested with mycelium, 

 turned out of a plant pot, in which a Begonia 

 was planted. The mycelium attacked the root 

 of the Begonia and killed it. Reduced. 



whether it is necessary to have uncultivated headlands at 

 all, I leave for the practical farmer to decide. 



Some years ago, a batch of begonias that had been potted 

 in leaf-mould went 'off' in a mysterious manner. On 

 investigation it was discovered that the leaf-mould in which 

 the begonias were planted was overrun by a dense mass 

 of white mycelium. As a rule leaf-mould contains mycelium, 

 and in this particular instance the mycelium or spawn of 

 some fungus proved predominant. This is only an isolated 

 instance of the destructive work done by fungus mycelium 

 present in leaf-mould. It can be prevented by intimately 

 mixing a small amount of kainit with the leaf-mould some 

 time before it is used. 



