DISEASES. 177 



have not blighted ; but it does not follow that they would 

 have suffered if let alone. 



Another form of blight may often be seen in tlte peach 

 and in the apple ; it consists in a loss of vitality of small 

 twigs and their foliage in several parts of the tree, espe- 

 cially in the inner portions that are not freely exposed to 

 the air and light. In the peach, this disease is accompanied 

 with the decay of the fmit upon these twigs, which rots 

 and becomes moldy. This trouble is usually attributed 

 to mildew, and it is probably owing to some form of fun- 

 gus invasion. 



Quite a different affection of the twigs is that known as 

 the " blight " in apples and quinces. This attacks only 

 the young ishoots of the current season's growth, which 

 suddenly wither and become brown at mid-summer. The 

 same condition occurs also in the shoots of the Italian 

 mulberry. The cause of this malady is not very apparent ; 

 by some persons it is attributed to the punctures of mi- 

 nute insects, but they have escaped the scrutiny of -other 

 observers, who attribute this blight to atmospheric causes. 



The tnie apple blight is a malady of very serious char- 

 acter, that invades many orchards in the Western States. 

 In its nature, and in the mode of its invasion, it very much 

 resembles the dreaded fire-blight of the pear, with which 

 most ovchardists have unfortunately become already but 

 too familiar. Like it too, all the guesses which Solons have 

 offered for the explanation of its cause, appear equally un- 

 satisfactory. 



A whole branch or limb of the tree becomes simultane- 

 ously affected ; sometimes one quarter or even one half of 

 the top is destroyed by the disease, and the removal of 

 8* 



