60 Tli6 Western Pomologist and Gardener. 1872 



look for Pear Blight the next season as to look for the season itself. But if, on the con- 

 trary, this unusual pruning is not performed the season before ; or, if the ground is not 

 rich ; or, the cultivation is too thorough and long continued ; or, the summer and fall not 

 too warm and wet ; if, in a word, everything shall conduce to a reasonable growth of 

 young wood, and that well ripened in due season ; and if, in addition to all this, the 

 changes of temperature above spoken of should not occur, it would be as reasonable to 

 look for an earthquake the next season as for the occurrence of Pear BligM. 



The above remarks go to show (if they are correct,) that the exciting or immediate cause 

 of blight is atmospheric. 



The nature of this disease lies in the ruptured cells of the outer wood and inner bark of 

 the tree affected. Being done in the winter, the disease does not show itself unless 

 searched for, until the growing season, and the deeper the freezing has gone, the more 

 fatal the disease. 



The sap being thus thrown outside of the pales of vitality, becomes as any other dead 

 matter ; it soon passes on to putrefaction. Bence we find it passing through all those 

 chemical changes, which is first stceet, then aleoTiolie, and lastly, putrefactive. Persons exam- 

 ining the sap of blighted trees, in some one of these different changes, have arrived at 

 different conclusions in regard to its nature. If the facts of these consecutive changes 

 are kept in view, few persons wiU differ as to the nature of this disease. 



TIME OF DEVEIjOPMENT OF THIS DISEASE. 



Because it docs not develop itself until late spring or early summer, generally, many 

 are led to refer it to the same cause, acting only at the time of the development ; hence, 

 the conflicting theories that have arisen in regard to this disease, some abandoning all 

 hope of ever understanding its nature. 



When the freeze has not been so severe as to penetrate deep into the sap-wood, the 

 young shoots put forth in the spring and grow as if there were no disease in the tree. 

 This continues until terminal buds are formed. When these buds are formed, and the 

 wood is done growing in length for the present season, the sap then turns down between 

 the wood and the bark to increase its diameter, by laying on its coats of new wood ; hence 

 it is that the descending sap meets with the dead sap and ruptured cells, produced by the 

 freeze, and becomes diseased, spreading its deleterious influence wherever it flows. Thi- 

 happening about the same time on the same tree, has given rise to the name of Firt- 

 blight, because of its sudden appearance. 



In proof of the above statement being a rational solution of this disease, we refer tn 

 the following historical facts : 



The summer of 1844 was one which produced an abundant growth of young wood, 

 and up to the 25th day of November there had been no frost, which are usually blighting. 

 The fall, up to this time was warm and pleasant, but about three o'clock of that day, a 

 dark cloud appeared in the northwest. About four o'clock it commenced to rain. In less 

 than an hour afterwards the snow came, followed very soon afterwards by sleet. This 

 sleet remained on the bodies of the trees to the thickness of an inch, for some days. The 

 mercury ran down to about zero, and changed but little from that till about Christmas. 

 The next sea.son was one of unparalleled destruction, in consequence of the blight, both 

 in pear and apple tree, as well as other fruit trees. As a confirmation of this opinion, 

 especially on my own place, I took up the same day, for the late Governor Helm, one 

 hundred trees. They reached his home too late in the afternoon to be transplanted. 

 They were put into his cellar over night, and were taken care of until planting time. 

 None of these trees were blighted, while a very large amount of the trees remaining on 

 my place were totally destroyed. The following spring, March, before warm weather 

 could have any influence on the trees, I found, in cutting off cions for grafting, that 

 nearly all of some varieties, especially on the east side, were surrounded, next the wood, 

 with a layer of brown bark, the wood itself partaking of the same disease. Nearly all of 

 he grafts failed. In this instance, the relation between /reezinfir and Uiglit is too dear to be 



