294 Bulletin 145. 



Sturgis, W. C. — ''Scab" of Apple and Pear. Bulletin iii, Conn. 

 Experiment Station, New Haven, ]892. 



Sturgis, W. C. — Diseases of the Pear. Scab. Bulletin 115, Conn. 

 Experiment Station, p. 5, 1883. 



Sturgis, W. C. — Spraying for ''Scab" of Apple and Pear. Report 

 Conn. Experiment Station, 1893, pp. 72-73. 



TUBEUF, K. F. von. — Diseases of Plants Induced by Cryptogamic Para- 

 sites, English Edition, pp. 218-220, also 507. 



PEAR BLIGHT.* 



i^Fire blight.) 



I. General Appearance. 



Of all the diseases which affect the pear, there is no other which 

 commands attention like the pear blight, or so-called fire blight. 

 One may say that it commands attention, for surely its injuries are 

 usually sufficiently evident — the progressive blackening of leaf and 

 twig, or the death of the tree limb by limb — injuries which must appeal 

 to any one with due interest, either aesthetic or pecuniary. The most 

 evident cases of blight are at first manifest on the tender shoots or 

 younger twigs by the blackened leaves and withered stems ; gradually 

 the progress of the disease is downward, an inch more or less each 

 day, it may be ; and finally the death of largest limbs may point out 

 the very destructive course of this malady. 



With the more susceptible varieties, and under conditions favoring 

 more succulent growth, blight may involve the entire body of the 

 tree. Often, however, the disease is temporarily or permanently 

 checked at definite places by the denser wood or other conditions, and 

 at such places there is a sharp line of demarcation between the healthy 

 part below, and the shriveled, blackened part above. In larger limbs, 

 this break is quite as evident by the cracked appearance of the bark. 



Unfortunately, the forms of injury above described are not the only 

 ones. Those who have suffered by this disease know well that fre- 

 quently the blossoms and the young fruit turn black and dry up. The 

 disease may then remain in the fruits alone, or it may here, also, 

 extend itself to larger limbs through the fruit spurs and twigs. 



* Bacillus ainylovorus, Burrill. 



