MARKET DISEASES OF APPLES, PEAES, QUINCES 19 



source of fruit infection, their removal in pruning or special surgical 

 operations has an important bearing on the control of the fruit rot. 



The fisheye rot caused by Corticium centrifugum is most common 

 on windfalls, doubtless because of its presence on decaying cover- 

 crop material under the trees. Consequently apples that have dropped 

 to the ground should never be packed with fruit for storage even 

 w^hen they are apparently uninjured, as is sometimes the case in 

 orchards having a heavy cover crop. 



No methods of control are known for the other three rots. (^^, ^i, 

 62, 99, 100, 101, lU, 186, 191^, 195, 24^, 2U') 



CHEMICAL INJURIES 



INJURY BY SALT, LIME, OR FERTILIZERS 



When railroad cars are used for the shipment of salted hides, salt, 

 fertilizer, or lime, either in bags or in barrels, there is usually some 

 wastage onto the car floor and walls. If such cars are afterward 

 used for the shipment of fruit in bulk, there is bound to be, at vari- 

 ous places, a close contact under pressure between the spilled chemi- 

 cal and the fruit. When this occurs, as observed most commonly with 

 apples, the fruits immediately in contact with the chemical become 

 noticeably flattened where they touch it, and the skin and underlying 

 flesh show a brown leathery condition. If salt is the chemical con- 

 cerned, it can often be detected by tasting the injured flesh. Fer- 

 tilizers and lime are less easily detected in this way, so that when 

 injury is found and either of these substances is suspected to be the 

 cause, diagnosis will have to depend chiefly on whether or not they 

 can actually be found on the car floor and walls. Injury comes about 

 only where the fruit lies in contact with the chemical, and it is usually 

 more severe in the layer next to the floor than in that next to the 

 wall. It is due apparently to the forcing of the fruit into or against 

 the chemical by the weight of the overlying load, combined with the 

 rubbing that results from the constant jolting and shifting about of 

 the load in the moving car. 



INJURY BY HYDROCHLORIC ACID 



Injury to apples caused by hydrochloric acid used in washing 

 treatments appears typically as a bleaching of the skin. It usually 

 appears within a day or two after washing. At first the color seems 

 merely to fade into the flesh and the skin softens, but later the skin 

 may crack through the center of the spots and become dr^^ and 

 papery. With age the spots become depressed, and sometimes the 

 presence of dissolved arsenic in the acid washing solution causes 

 them to turn black. The appearance and severity varies somewhat 

 with different varieties, and sometimes the presence of a few tiny 

 black freckles found at lenticels on stored fruit, especially Winesap 

 and Arkansas Black, may be the only indication of acid injury. 

 Such spots might easily be mistaken for Jonathan spot. 



Acid injury is sometimes localized in the stem or calyx regions 

 or at points where the apple has remained in contact with other 

 objects; but usually the injured areas are scattered irregularly oyer 

 the apple, marking places where drops of acid washing solution 

 evaporated. Where drops of this solution concentrate to an in- 



