PEAR DISEASES 337 



PlNK-RoT 



Caused by Cephalothecium roseum (Fries) Cda. 



This is one of the most common of the storage rots of the 

 pear. It also occurs while the fruit is still on the tree. Where 

 found it may be seen on examination that the pink-rot patho- 

 gene, Cephalothecium roseum, has gained entrance through scab 

 spots, or through breaks in the skin due to careless handling of 

 the fruit. When scab is controlled and the fruit carefully 

 handled, pink-rot is reduced to a minimum. (See Apple, 

 page 117.) 



MYCOSPELERELLA LEAF-SPOT 



Caused by Mycosphcerella sentina (Fr.) Schrot. 



The pear-leaf disease here discussed is better known as leaf- 

 spot, Septoria leaf-spot and ashy leaf-spot. It was first de- 

 scribed in the United States in 1897. During that and the 

 succeeding year it was a prominent and important pear trouble. 

 In fact, the disease is usually common every year. The rav- 

 ages of the disease have always been confined to the eastern 

 portion of the United States, whereas in Europe it is wide- 

 spread. Orchard trees and nursery-stock suffer alike. A 

 few cases have been found on apple-foliage. 



This leaf disease is capable of bringing about considerable 

 damage to the pear. Leaves are frequently so badly infected 

 that premature defoliation takes place in August or earlier. 

 This results in checking the growth of the affected tree and 

 prevents the proper ripening of -the buds and shoots. This 

 untimely defoliation may also cause the tree to put out new 

 growth which cannot harden before winter. Thus the tree is 

 made sensitive to winter-injury. 



Some varieties of pears are more affected than others. It 



