ABOUT FRUITS, FLOWERS AND FARMING. 395 



cned trail as of a slimy insect, of an ash color. The wood 

 sullVrs very little by this summer-blight, and sometimes 

 none. The winter-blight is found on almost all kinds of 

 trees. This summer it has affected the apple, the pear, the 

 peach, the quince, the English hawthorn, privet, black 

 birch, Spanish chestnut, elder, and calycanthus. I enume- 

 rate the most of these kinds on the authority of J. H. 

 James, of Urbana, Ohio, and C. W. Elliott, of Cincinnati, 

 having observed it myself only on fruit-trees. 



II. THEORIES. A variety of theories exist as to the 

 causes of this disease. Some are mere imaginations ; some 

 are only ingenious ; and some so near to what I suppose to 

 be the truth, that it is hardly possible to imagine how the 

 discovery was not made. 



The injury is done in the fall, but is not seen till spring 

 or summer, or even the next fall. Thus, six months or a 

 year intervene between the cause and the effect a sufficient 

 reason for the difficulty of detecting the origin of the evil. 



1. Some have alleged that the rays of the sun, passing 

 through vapors which arise about the trees, concentrate 

 upon the branches, and destroy them by the literal energy 

 of fire. Were this true, the young and tender shoots would 

 suffer first and most ; all pear-trees would suffer alike ; all 

 moist and hot summers would be affected with blight ; her- 

 baceous plants would suffer more than ligneous : all of 

 which results are contrary to facts. 



2. Some have supposed the soil to contain deleterious 

 substances, or to be wanting in properties necessary to 

 health. But in either case such a cause of the blight ap- 

 pears untrue, when we consider that trees suffer in all soils, 

 rich or poor ; that, in the same soil, one tree is blighted 

 and the next tree escapes ; that they will flourish for twenty 

 years and then blight ; that a tree partially diseased recov- 

 ers, and thrives for ten or more years without recurrence of 

 blight. 



3. It has been attributed to violent and sudden changes 



