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Vol. I. Des Moines; Leavenworth, March 15, 1872. No. 3 



MABK MILLEB, Managing Editor and FnHislier, Des Moines, lowai 

 Dr. J. Stayman, Dr. Wm. M. Howsley, Dr. S. H. Kridelbaugh, 



Associate Editor, Leaveaworth, Kansas. CorrespoodiQg Editor, Leavenwortli, KaDsas. Eotomologicai Editor, Ciarloda, Iowa. 



The Pear and Its Cnltare.— Contlnned. No. 3. 



By Tbe Cobrespondino Editob. 



Having spoken of the fruit and the tree of the Pear, in their supposed healthy con- 

 dition, we will now turn our attention to the diseases which affect the tree. Of these the 

 most formidable is what is usually called the Pfar 5%7(<. In approaching this subject, we 

 are aware that we are treading upon strongly controverted ground. So numerous are 

 the theories upon the subject, that we cannot reasonably hope to convince every one that 

 we have taken a proper and common sense view of this disease. We will, nevertheless, 

 enter into this controversy fearlessly, feeling that yre can support our views with facts 

 enough to show that we have, in the main, at least, taken the correct position on this 

 subject. First, then, without stopping here to canvass some of the most common views 

 as that o{ fungus origin of this disease, or of that which attributes it to wet weather, we 

 will proceed to point out what we consider to be the cause or causes of this disease. 



Blight, although manifesting itself in different degrees and at different times, is strictly 

 reducible to two kinds, and to two seasons, each resulting in the same consequences, whick 

 differ only in degree. 



CAUSES. 



No one single cause will scarcely, if ever, produce this disease. It requires a combina- 

 tion of causes to give it full developcment. In speaking of the causes of blight, we will 

 divide them into Remote, Predisposing, and Proximate or Exciting causes. 



Remote causes, or those which lie at a distance from its development, are such as unu- 

 sually heavy pruning the year previous to the showing of the disease ; wherever very 

 extensive pruning-out has been practiced the preceding year, so as to greatly lessen the 

 top of the tree in order to give it shape, the preponderance thus given to the root neces- 

 sarily gives rise to a large amount of young wood, which cannot, or does not ripen. This 

 pruning is therefore a remote cause, but cannot of itself produce the disease. 



Predisposing causes consist mainly in having the trees planted in too rich ground, in 

 too deep and thorough cultivation and too long continued ; in a wet, warm summer and 

 fall ; In an unusual amount of young and unripened wood. These may be added to the 

 above remote cause, and yet the trees may pass through the winter without serious injury 

 and become all right the next season. 



The proximate or existing causes lie in a sudden and severe change of temperature in 

 the weather, particularly from unusually warm to unusually cold, and that in a very short 

 time ; in intensely cold weather during winter, and that long continued. 



Whenever, therefore, we have the remote cause of heavy pruning ; the predisposing 

 causes of rich ground ; of thorough and late cultivation ; of warm, wet summers and falls ; 

 of large amount of young and unripened wood ; and, if added to these, we have sudden 

 and severe changes from heat to cold in the fall or winter, we may almost as reasonably 



