PEAR DISEASES 351 
Sooty-BLotcu anp Fiy-SpecK 
Caused by Leptothyrium pomi (Mont. and Fr.) Sace. 
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.) 
Buack-Mo.p 
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. 
Buack-Rot CANKER 
Caused by Physalospora Cydonia 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 Cydonia, 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 
