176 DISEASES OF THE PEAR. 



sometimes the consequence of overbearing, in which 

 case, the dead bark will often cover the living and 

 most healthy wood and bark ; yet this peculiarity is 

 frequently the first stage of the disease. 



3. By the extremities of the shoots in early summer 

 shrivelling, turning black, and perishing suddenly 

 "When these are instantly cut away for some distance 

 below the diseased j)arts, the tree may often be saved ; 

 but if the dead patches of bark, above mentioned, 

 first make their appearance, the case is critical. 



THE DsSECT-BLIGHT. 



The insect causing this blight is known among po- 

 mologists as the Scolytus j)yri^ and is one of the most 

 minute of our numerous enemies. 



In July or August it perforates shoots of sometimes 

 two seasons' growth, and deposits its Qgg. The suc- 

 ceeding June or July, the branch is observed to wither 

 and turn suddenly brown. The disease seldom travels 

 below the point attacked, and if the part be removed 

 immediately, is directly checked. The insect engen- 

 dered near a bud eats its way to the pith, and there, 

 by feeding upon the sap-vessels, destroys the organ- 

 ism that supplies life to the ujDjDer shoot. At the 

 first appearance of the ravages of the insect, all the 

 branches aflected should be cut and burned — the 

 attack must be sudden and energetic. 



THE LEAF-BLIGHT. 



This disease is indicated by a sudden spotting and 

 premature ripening of many of the leaves. The 

 growth is checked for a time, and if the attack is long- 



