DISEASES, IXSECTS, AND ANIMALS INJURIOUS TO FOREST TREES. 2 / 7 



XXXIII. Diseases, Insects, and Armnals Injurious to Forest Trees. 

 By Gilbert Brown, Forester, Beaufort. 



Diseases In-jurious to Pines. 



Speaking broadly, there are two great classes of diseases which 

 imperil the life of conifers. There are, on the one hand, diseases 

 due to the action of animals and plants, which injure or destroy 

 the roots, stem, or leaves, etc., of conifers, and so bring about the 

 death of the whole or part of them ; and, on the other hand, there 

 are dangerous physical conditions of soil, climate, atmosphere, 

 etc., which render the life of conifers more or less impossible. 

 These two classes of dangers are frequently found acting together, 

 and so a given case of disease may be complicated owing to the 

 co-operation of many factors. The symptoms, too, of one disease 

 may more or less closely resemble those of others, and thus dis- 

 crimination and determination may be a matter of difficulty. 



So many are the diseases of trees due to parasitic fungi, it would 

 be impossible to deal with the whole. I will therefore only deal 

 with serious diseases, and those are seen in our everyday routine. 

 Some of the most deadly and common are Trametes radiciperda^ 

 Agaricus melleus, and Feridermumi pini. These fungi differ con- 

 siderably in their mode of action and manner of inducing disease, 

 but they all eventually destroy the timber of the trees by dissolv- 

 ing and consuming the structural elements. The conducting and 

 supportive functions of the wood are interfered with, and death of 

 the whole or a part of the tree is the result. 



Trametes radiciperda. 



This disease attacks the roots of the Scots fir and a few other of 

 the pines, sending its snow-white mycelium beneath the bark and 

 travelling thence up the stem, to finally penetrate the wood by 

 way of the cambium and inner parts. The rotting of the wood 

 rapidly follows, and other symptoms so peculiar appear that 

 the presence of this fungus can be concluded with certainty 

 from them. Owing to reddish discoloration of the timber which 

 results, the disease has been termed red-rot. This disease is 

 extremely difficult to eradicate, because the mycelium travels 

 from root to root in the soil, and the spores are supposed to be 

 carried by burrowing animals from one place to another or by 

 direct infection from the roots of neighbouring trees. 



