14 The Blight in Pear Trees. 



to induce the examination whether the notion of an insect 

 bhght rests on any sufficient authority. 



Until 1844, I was a firm beHever, on the report of others, 

 that the fire bhght in pear trees was caused by an insect, and 

 that the spread of its ravages might be checked and prevented 

 by a prompt amputation of the affected hmbs, and a consump- 

 tion of them by fire. In that year, for the first time since I 

 became a grower of trees, I found fire bhght in my garden ; 

 and, as I had, within a few days previously, heard a paper 

 read by Dr. Mosher before the Cincinnati Horticuhural Soci- 

 ety, describing minutely the action of these insects, (not the 

 scolytus, however,) and the causes why they liad failed to 

 be discovered when sought for, I hastened to apply the knife 

 as he had advised. When I came to amputate the limb, 

 which had caught my eye from a long distance, I was sur- 

 prised to find that the appearance did. not accord with Dr. 

 Mosher's description of the disease, which he represented as 

 " first making its appearance at the extremity of a single 

 branch when in full leaf, and from the young twigs of the 

 present year's growth extending down the limb, to the older 

 wood." In my case, the branch, a strong upright shoot, was 

 six feet long, and about midway of its length for the space of 

 20 inches, the leaves were of a shining black color, and, dur- 

 ing the same extent, the bark was shrivelled, while the ex- 

 tremity of the branch was still green and flourishing. 



My examination of the tree did not enable me to discover 

 the presence of any insects, but, assuming that they were cer- 

 tainly there, I cut off the entire limb close by the trunk of the 

 tree, when I found the sap diseased below the bark. Accord- 

 ing to the books, I expected to find an exhausted state of the 

 sap, not a vitiated redundancy. Two days after, I found the 

 like mark of black leaves on another limb, when I cut into the 

 base of all the limbs, and found the entire top, including the 

 upper part of the trunk, in a diseased state, which I would 

 describe as a putrid fermentation. Between the bark and the 

 alburnum, the sap was profuse, viscid, and discolored, hav- 

 ing the smell of a spoiled watermelon. My further observa- 

 tions led me to conclude that this sap dries up after a few 

 days, leaving a brownish color on the surface of the albur- 

 num, followed by a shrivelling of the bark. Mr. Downing 



