PEAR DISEASES 351 



SOOTY-BLOTCH AND FLY-SPECK 



Caused by Leptothyrium pomi (Mont, and Fr.) Sacc. 



The pear fruit is sometimes affected by the sooty disease 

 which occurs so commonly on the apple in a wet season. It is 

 rarely troublesome to the pear-grower. (See Apple, page 104.) 



BLACK-MOLD 



The fungus Fumago vagans Fries 



The leaves, twigs and fruits of pears, apples and cherries are 

 sometimes badly discolored by the growth of the fungus Fumago 

 vagans in the honey dew secreted by lice. The fungus is dark 

 and its development is so extensive that it presents a very con- 

 spicuous black or sooty mold aspect. Since F. vagans lives in 

 the honey dew, it is most prevalent in epidemics of the pear 

 psylla and apple louse. The fungus itself needs to cause no 

 fear; it may be eliminated by controlling the above-named 

 insects. 



BLACK-ROT CANKER 

 Caused by Physalospora Cydonice Arnaud 



The fruit, leaves and branches of the pear are attacked 

 occasionally by the above-named fungus, and as a result a 

 black-rot, a leaf-spot or a canker may be produced. Special 

 reports of it have come from New York, Texas and Ohio, and 

 it doubtless has a wide range over the eastern United States. 

 The causal fungus, Physalospora Cydonice, is very common, 

 infesting dead bark of many woody plants. It readily attacks 

 healthy bark of the pear and apple whenever an injury affords 

 entrance. In this connection it has been suspected as the 

 cause of the failure of grafts, killing the end of the stock in 



