444 The Blight in the Pear Tree ; 



4. Others have attribnied the disease to over stimulation 

 by Iiigh manuring, or constant tillage ; and it has been said 

 that covering the roots with stones and rubbish, or lay- 

 ing the orchard down to grass, would prevent the evil. 

 Facts warrant no such conclusions. Pear trees in Gibson 

 county, Indiana, on a clay soil, with blue slaty subsoil, 

 were aifected this year more severely than any of which 

 we have heard. Pears in southern parts of this State, on 

 red clay, where the ground had long been neglected, suf- 

 fered as much as along the rich bottom lands of the Wa- 

 bash about Vincennes. If there was any difi'erence it was 

 in favor of the richest land. About Mooresville, Morgan 

 county, Indiana, pears have been generally afiected, and 

 those in grass lands as iniich as those in open soils. Aside 

 from these facts, it is well known that pear trees do not 

 blight in those seasons when they make the rankest growth 

 more than in others. They will thrive rampantly for years, 

 no evil arising from their luxuriance, and then suddenly 

 die of blight. 



5. It has been supposed by a few to be the effect of age^ 

 the disease beginning on old varieties, and propagated upon 

 new varieties by contagion. Were this the true cause, we 

 should expect it to be most frequently developed in those 

 pear regions where old varieties most abound. But this 

 disease seems to be so little known in England, that Lou- 

 don, in his elaborate Encyclopedia of Gardenings does not 

 even mention it. Mr. Manning's statement will be given 

 farther on, to the same purport. 



6. Insect theory: The confidence with which eastern 

 cultivators pronounce the cause to be an insect, has in part 

 served to cover up singular discrepancies in the separate 

 statements in respect to the ravages, and even the species 

 of this destroyer. The Genesee Farmer of July, 1843, 

 says, " the cause of the disease was for many years a mat- 

 ter of dispute, and is so still by some persons: but the ma- 

 jority are now fully convinced that it is the work of an in- 

 sect, {Scolt/tus pyri.) T. W. Harris, in his work on insects, 

 speaks of the minuteness and obscure habits of this insect, 

 as " reasons why it has eluded the researches of those per- 

 sons who disbelieve in its existence as the cause of the 

 blasting of the limbs of the pear tree." Dr. Harris evi- 

 dently supposed, mitil so late as 1843, that this insect in- 

 fested only the pear tree ; for he says, " the discovery of 



