FUNGI IMPERFECTI 



351 



and northern central states, as well as in Canada, and it is not 

 improbable that it is more or less distributed throughout the 

 country. Under other scientific names, moreover, it may also be 

 known botanically, at 

 least, in Europe. 



As a rot of fruit the 

 fungus is more generally 

 known in America. It 

 is a brown rot, begin- 

 ning as a small spot, fre- 

 quently near the bud end 

 of the fruit, and spread- 

 ing until the whole fruit 

 may be involved. There 

 is not such characteristic 

 shrinkage of the tissues 

 as in the case of the bit- 

 ter rot. The pycnidial 

 pustules may begin to 

 appear when the spot is 

 only half an inch in di- 

 ameter, or they may not 

 become evident until the 

 entire fruit is decayed. 

 This rot often attacks 

 the fruit on the trees, 

 yet it is far more com- 

 mon upon the neglected 

 fallen fruit (Fig. 169), 

 which is a great source 

 of danger to the health 

 of the tree. In the mild- 

 est form the canker is believed to cause merely a greater rough- 

 ening of the bark, an injury which may occur as a single spot, 

 or which may extend along the limb for a distance of several feet. 

 In the most serious cases it first destroys the bark, well-marked 

 depressed areas being developed, about which local swellings of 

 the limbs occur, and in these affected areas the wood at the center 



FIG. 170. THE SPH^EROPSIS CANKER OF APPLE 

 (Photograph by H. H. Whetzel) 



