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brown, the sap is thick and unctious, with a sour odor like fermented water- 
melon, or tops of potato vines after being frosted. The odor may be per- 
ceived at some distance from the trees. Bark sometimes bursts and acrid 
sap exudes, which destroys vegetation on which it drops. This is called the 
true winter blight; summer blight only injures the leaves. 3 
Theories:—1, rays of the sun passing through vapors; 2, poor or dele- 
terious soil; 3, violent changes of the temperature of the air, or of the mois- 
ture in the soil, sudden change from sward to high tillage, resulting in 
“surfeit” or ‘‘overplus” of sap; 4, stimulation by high manuring or constant 
tillage; 5, effects of age—old varieties being most subject to it; 6, attacks 
of insects—Scolytus pyri, aphides, ete. 
Cause of blight:—Autumn freezing of unripe wood, which engenders a 
poison that destroys the shoots and branches in the following season. This 
is elaborated in extenso. 
Proofs of the theory are: 1. The two great blight years of Indiana were 
1832 and 1844, and they were preceded by early and severe autumn freezing. 
2. It mav be predicted the winter before its occurrence by experienced nur- 
serymen, in individual trees or limbs. 38. Late winter or early spring prun- 
ing shows a viscid sap in affected limbs. 4. Trees which ripen their leaves 
and wood early are least affected. 5. Wherever artificial causes have either 
produced or prevented a growth so late as to be overtaken by a freeze, blight 
has, respectively, been felt or avoided. 6. An orchard favorably situated to 
ripen its wood early in 1843 had no blight in 1844, while all about it had. 
7. The fact that blight first appears low down on branches is no objection, 
as that is where the returning sap ‘‘effects a lodgment.” 8. Spring frosts 
do not produce it, for im 1834 they were severe in May, and no blight fol- 
lowed. 9. Forest trees do not suffer much because protected by one an- 
other. 10. Fall-growing shrubs may not be as susceptible to injuries by 
freezing. +11. Spring-grafted shoots get their blight from the stock which 
has been exposed tg the winter. 12. Spread of the disease through the tree 
is due to the malignant sap where killed by freezing. 13. Trees of vigorous 
constitution are sometimes able to throw off the disease. 14. Rich and dry 
soil gives vigor and prevents blight; rich and moist soil forces growth and 
prepares for blight. ' 
Remedy: 1. Light, rich and dry soil. 2. Varieties that early ripen their 
wood. 38. Rvot-pruning when in danger of late fall growth. 4. When it 
has occurred resort to ‘‘free and early cutting.” 
Additional items: This blight is not to be confounded with winter killing. 
The ‘‘Yellows” is believed to be a ‘development of the blight according to 
the peculiar habits of the peach tree.” 
1845. DownineG, A. J. Fruits and fruit trees of America, 
1845, p. 822. [64 pages on blight. | 
Same, rev. by Chas. Downing, 1857, p. 412. [63 
pages. | 
Same, 2nd rev. by Chas. Downing, 1885, p. 644. [54 
pages. | 
‘This disease has been, at different times, the terror and despair of pear 
growers.”’ Has been known for nearly a hundred years, but notions of its 
character and origin have been so vague as to lead to few practical means 
for controlling it. A page is given to the insect blight and remedy, caused 
by Scolytus pyri. 
Fire blight is treated under the heading of ‘‘frozen-sap blight.” Symp- 
toms are (1) a thick, clammy sap at winter or spring pruning, (2) dead 
patches of bark on trunk or large branches seen in spring, and (8) rather 
sudden dying of extremities in early summer. In severe cases it may ex- 
