22 The Blight in Pear Trees 



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lications in the Neio England Fai-?ner, and Mr. Fessenden, 

 in a review of facts, declared that "further investigation into 

 the cause and consequence of the malady in pear trees, led 

 him to doubt the correctness of his first formed opinion." 

 " We now doubt," said he, " whether the Scolytus Pyri 

 can be the perpetrator of all the mischief which we were at 

 first disposed to attribute to his agency." 



It might be supposed, from Mr. Downing's description of in- 

 sect blight, that he means to be understood, that there is a 

 blight in pear trees, unaccompanied by a vitiated state of the 

 sap. But I apprehend that this is an error. 



Frozen Sap Blight, or Winter Blight. — In what I con- 

 sider the uncertainty of the mode in which this injury hap- 

 pens, I prefer, as I have already stated, Mr. Beecher's term 

 of winter blight. The name, frozen sap blight, would some- 

 what import, that mere intensity of cold, and a freezing of 

 the sap, would prove destructive to the trees. The conjec- 

 ture is, that the freezing ruptures the sap vessels, and destroys 

 their capacity for transmitting the sap. The nature of the 

 injury could doubtless be solved by the aid of microscopic ob- 

 servations, which could be readily invited, and made efficient, 

 by the Smithsonian Institute. All gardeners, at least, will 

 unite in testifying to them, that knowledge on this subject is 

 worthy of extension and difl\ision among men. 



Mr. Downing states, very confidently, that the sap becomes 

 polso?ied, and, by dilution with other descending sap, is car- 

 ried down, infecting the tree below, and part carried inwards 

 towards the pith, poisoning the alburnum. Is this the result 

 of observation, or is it conjecture 1 I apprehend it is the lat- 

 ter. From such observations as I have made, perhaps too 

 limited, the conclusion I formed was, that the sap, after fer- 

 mentation, was no longer transmissible, and soon dried up, 

 after which, the bark shrivelled, and producing, in fact, a de- 

 cortication. If the sap is poisoned and carried inwards, it would 

 also ascend through the alburnum, and infect the top. But this 

 is not the case : grafts taken from a blighted top, will grow 

 into healthy branches, as I have seen, and as Mr. Lazell, of 

 Columbus, also testifies. The injury may be regarded as en- 

 tirely local. I have seen a single fruit-spur blighted on the 

 side of a healthy limb, and, on seizing it, to pull it away, the 



