118 DISEASES AND ENEMIES OF PEAR TREES. 



or two after the disaster appears. As the malady 

 extends downwards, the limb should be cut off two 

 or three feet below all appearance of the blight. 

 When promptly and thoroughly applied, this rem- 

 edy has proved completely effectual. But a fear- 

 less application of the remedy will only insure 

 success. All delays and half-way attempts will 

 end in failure. 



The cause of this disease is a matter of dispute. 

 Professor Peck and others believe it to originate 

 from an insect (Scolytus pyri,} which eats round 

 the branch under the bark. Hence all affected 

 limbs, when removed, should be committed to the 

 fire, to prevent further ravages. Others again, as- 

 cribe it to the influence of cold on late-growing 

 unripened wood.* Both these causes may produce 

 it, as the insect has evidently been discovered ; 

 and again numerous cases have occurred where the 

 closest examinations have failed in its discovery.! 

 But the same remedy, the removal of the branches, 

 is equally applicable to both, and equally success- 

 ful ; in one it prevents the further ravages of the 

 insects ; in the other, it prevents the extension of 

 the disease by the downward flow of the poisoned 

 and fermented juices from the affected limbs. 



* Which must not be confounded with winter-killing-, 

 causing death at once, the influence of the cold being only 

 sufficient to produce disease in the case mentioned, eventu- 

 ally resulting in death. 



f For a full explanation of this theory, and for several 

 striking cases in illustration, see Cultivator for 1845, p. 5L 



