104 MANUAL OF FRUIT DISEASES 



in many cases for producing wounds through which Clitocybe 

 parasitica may enter. 



Control. 



This root-rot disease is subject to the same remedial measures 

 as those prescribed for the Armillaria root-rot. (See page 100.) 



REFERENCE 



Wilcox, E. M. A rhizomorphic root-rot of fruit trees. Oklahoma 

 Agr. Exp. Sta. Bui. 49 : 3-32. 1901. 



SOOTY-BLOTCH AND FLY-SPECK 

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



Certain varieties of apples show this very familiar disfigura- 

 tion. The Rhode Island, Peck Pleasant, Rome, Baldwin and 

 Northern Spy are regarded as most susceptible, although in 

 general the disease is most noticeable on light-colored varieties. 

 English growers find that the Newton Wonder is affected more 

 than other varieties. This disease is also found on pears, 

 particularly on the varieties Anjou and Lawrence. 



The injury produced is not deep-seated, consequently the 

 disease is not so serious from the standpoint of destructiveness 

 as would first appear. The growth of the affected fruit is not 

 checked, nor does the real quality of the fruit seem to be im- 

 paired. But the apple is blemished and thus it may be ren- 

 dered unmarketable ; at all events, fruit affected with sooty- 

 blotch is less salable than clean fruit. While the chief loss lies 

 in the lowering of the market value of the fruit, it should be 

 noted that later ill effects are sometimes shown in the wilting 

 of affected fruit and even in the decay induced by organisms 

 which are always ready to take advantage of a weakened apple. 

 Although no dollar estimates of losses incurred by this disease 

 are at hand, its economic importance cannot be questioned. 



