303 
tend throughout the tree. This is explained by saying that early autumn 
freezing changes and poisons the sap, and the pois on is distributed by the 
movement of sapin spring. In support of this theory it is pointed out that 
those varieties ripening their wood early in autumn, like the Seckel, are 
least affected. . 
Preventive measures are to avoid wet and unduly enriched soiis, late sum- 
mer pruning, and those varieties which ripen their wood late. When late 
growth cannot be avoided resort to root pruning and apply lime. Cut away 
call diseased branches as soon as seen. 
1846. Harton, L. C. (Providence, R. I.) Review of opinions 
on pear tree blight. Hort., vol. 1, 1846, pp. £59, 495. 
[45 + 5 pages. | 
Distinguishes between the true pear blight and that caused by the insect, 
Scolytus, then examines the theories which ascribe the former (a) to elec- 
tricity and atmospheric influence, () to old age or long duration of varie- 
ties, (c) to a sudden freezing of the bark, and (d) to an epidemic transmitted 
by the air. 
Judge Buel in 1828 in the New England Farmer, and the editor of the 
Genesee Farmer in 1833, championed the insect theory. In the New Eng- 
land Farmer for 1829 a correspondent ably answers Judge Buel, and argues 
that electricity and rarification of the air produce blight. Forsyth and 
Prince ascribe it to sun-stroke. Coxe, following European thought, favored 
the view that it is connected with the enfeebling of varicties by age. If it 
were an epidemic or in any way related to Asiatic cholera, the whole tree 
and all varieties would be alike affected. These several theories are care- 
fully treated, their weak points displayed, and additional facts supplied. 
The frozen sap theory of Downing is finally thought to best accord with the 
facts. Careful examination of his own orchard before leaves appeared in 
spring convinced him that the injury which becomes conspicuous in June is 
really begun in the winter. Late succulent growth is to be avoided ; pears 
worked on quince, and root pruning for rich soils, are advocated. 
1846. G[ooxrns], S. B. (Terre Haute, Ind.), and A. J. 
Downing. Remarks on the pear blight of the west. 
Hort., vol. 1, 1846, p. 253. [8 pages. ] 
Does not agree with Mr. Beecher regarding the cause. May 10th, 1834 
was a very severe frost, killing fruit buds of forest and fruit trees alike, yet 
it was not followed by blight. Other like instances given. An objection 
to the theory is that old trees are attacked rather than young ones. Another 
objection is that freezing does not change the sap to render it poisonous; 
death by freezing is not occasioned by deleterious properties imparted to the 
sap; the small branches of the trees freeze every winter. Yet blight is evi- 
dently a ‘‘disease of the circulation,” as proved by the following instance. 
Visiting Mr. Ragan in 1845, he was shown a thrifty young pear tree in the 
nursery, which had been ‘‘inoculated by way of experiment” with ‘‘the sap 
of a blighted tree” ‘‘a few days previous.” ‘‘He had made an incision about 
‘three feet from the ground, lifted the bark as in the process of budding, and 
injected a small quantity of the diseased sap.” ‘‘We found the leaves of the 
patient changing color, and emitting that peculiar odor which indicates the 
incipient state of decay, which is always present in cases of blight, and upon 
applying the knife, the inner bark was found to be black from the root to 
the top, while nothing of the kind appeared elsewhere in the nursery.” 
Objects to whitewashing as a preventive, as the disease ‘‘is contracted at 
the extremities,’? which is not touched by the whitewash. 
“T strongly incline to the belief that the pear blight is an epidemic; that 
it prevails like other epidemics, and will pass off like them. The atmosphere 
