CHAPTER YT. 



DISEASES OP CONIFERS. 



The diseases incident to this order of plants are compar- 

 atively very few, and, as a general rule, mostly confined 

 to a few species, and restricted probably to certain condi- 

 tions of the atmosphere and soil. The causes that influ- 

 ence the appearance and dissemination of a portion of 

 these evils are not at present sufficiently understood; 

 nevertheless we will give the most approved views on the 

 subject, hoping thereby to induce more careful experiments 

 which shall tend to counteract the direful effects of at least 

 a part of these maladies. 



As already stated, a rich soil abounding in organic ma- 

 nures, is, no doubt, one of the chief causes that produce 

 unhealthiness in coniferous trees, by inducing a strong suc- 

 culent growth which rarely allows the young tree sufficient 

 time to mature its wood, and consequently, if not killed 

 by the severe cold, it very frequently becomes in a man- 

 ner diseased, and after lingering a few years ultimately dies. 



Another source of disease, and one also to which we 

 have already called attention, is that of an imperfectly 

 drained soil. Disease often occurs to the tree from this 

 very simple, yet baneful cause, which will eventually de- 

 stroy its life, although oftentimes it may linger for several 

 years, gradually, though surely, approaching its death. 

 There is no doubt that three-fourths of the diseases com- 

 mon to this family arise from the two causes just alluded 

 to ; an unhealthy condition is indicated by the appearance 

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