i8 DISEASES OF TREES 



case of diseases of the cortex it is sufficient to make a fine inci- 

 sion with the point of a scalpel, to which a drop of water, with 

 spores suspended in it, is attached ; in the case of diseases of 

 the wood the latter must be pierced by the wound, which is 

 then allowed to absorb the drop of water with its contained 

 spores. 



In dealing with diseases of the cortex or wood, infection by 

 means of mycelium* is the much surer course. Having removed a 

 small piece of the cortex from that part of a diseased tree where 

 the mycelium is still young and vigorous that is to say, from the 

 boundary between the dead and living tissue, we place it on a 

 spot in a healthy tree from which a piece of cortex of the same 

 size and shape has been removed. We may proceed exactly as in 

 budding roses, but it is generally better if the edges of the piece of 

 cortex containing the mycelium are brought into intimate contact 

 with the edges of the cortex surrounding the spot operated upon, 

 and which, moreover, should be prepared immediately beforehand. 



Desiccation should then be prevented by applying grafting-wax 

 or other dressing. If it is desired to infect the wood of the stem 

 of a tree with mycelium, a small cylindrical block is removed 

 (by means of Pressler's growth-borer, an instrument specially 

 adapted for such work) from the boundary between the sound 

 and diseased wood, because it is usually only in this region that 

 the mycelium contained in the wood is still capable of such 

 vigorous growth as to be able to extend beyond the surface of the 

 infecting block. With the same borer an exactly similar hole is 

 then made in the sound tree selected for infection, the diseased 

 cylinder being substituted for that which was withdrawn, and 

 the hole closed externally with grafting-wax. 



If, finally, we have to do with parasites which vegetate under- 

 ground, it suffices, as a rule, to plant a diseased specimen in 

 immediate proximity to a healthy plant of the same species. In 

 doing this greater success will probably be secured by bringing 

 a root of the diseased individual (known to contain mycelium 

 still living and capable of growth) into immediate contact with 

 a root of the plant to be infected. 



* [The mycelium is the vegetative part of the fungus, and in many cases is 

 more easily obtained in the requisite quantities than spores are : a rough 

 equivalent for the word in English is ." Spawn " (of mushrooms, &c.) ED.] 



