6 Blight in Jlp-ple and Pear Trees. [July, 



will but recur to past experience, will be satisfied of the fact. 

 The disease of fruit trees, which is usually known as the blight, 

 by no means stands in striking contrast with the potato disease. 

 In fact many of the phenomena of each are quite similar, both in 

 appearance and in their ultimate results. 



The potato disease commences in the leaf and stem, beginning 

 with a drying of the former upon its edges, and extending rapidly 

 through the whole texture. The same effects follow with all the 

 leaves in quick succession, and sometimes, when the cause acts 

 intensely, the stems and leaves become perfectly brown and crisp 

 in a few hours. The same changes take place in the blight of 

 fruit trees ; first a leaf becomes brown and crisp, or several of 

 them are attacked simultaneously, and the first thing which at- 

 tracts our notice is the perfect death of a small branch which hangs 

 down in the midst of a perfectly healthy vegetation. 



The disease may commence in the middle of a large limb and 

 extend both ways, and it often happens that the termination of 

 the branch, the newly formed wood, is the last to die. If a limb 

 partially destroyed by the blight is closely inspected, the following 

 phenomena may be usually observed. Patches of brow^nish bark 

 on the sides of the limb. These do not extend entirely around it. 

 These appear at irregular distances, and are separated from each 

 other by living bark, but they soon coalesce and extend around 

 the limb, as well as in the direction of the base and apex. But 

 accompanying the death of the bark of the limb, there is also the 

 death of the apex of the expanding leaf buds. If these are closely 

 examined, they are frequently found softened and of a blackish 

 brown color, and the attachment of the surrounding leaves will 

 begin to be loosened, the whole circulation being cut off or de- 

 stroyed. 



If the whole limb is observed, then, in this disease, while it is 

 pro""ressing, a close inspection reveals patches of a brownish or 

 leaden hue, and a slightly wrinkled state of the cuticle — the leaves 

 ])rovvn in spots, others totally brown and dry, and ready to fall off. 

 If now we make an incision so as merely to raise up the cuticle, 

 the cellular tissue below is perfectly brown, or blackish brown; 

 the junction of the bark with the wock! is also discolored, and the 

 wood beneath soon becomes dry and hard, and perfectly impervi- 

 ous to the fluids of the limb. 



If the above description is true, our intelligent readers will 

 scarcely fail to recognize in the symptoms and progress of the 

 disease a true vegetable mortification, beginning with a death of 

 the outside, which proceeds from a small surface upwards and 

 downwards, and also inwards. The circulation in the centre of 

 the limb proceeds languidly for some time, so far at least as to 

 furnish nutriment to the extremity, while all below^ is dead and 



