8 CIRCULAR 740, U. S. DEPARTMENT OF AGRICULTURE 



AMMONIA INJURY 



The appearance of ammonia injury on apples is recognized by a 

 prominence of the lenticels, which become white at the center, with 

 some or many surrounded by bands of black on the red surfaces or of 

 green on the yellow-green areas. Even short exposures to small con- 

 centrations of ammonia will produce these color changes. When 

 ammonia concentrations are 2 to 5 percent, an exposure of 5 to 8 

 minutes results in prominent lenticels with the surrounding discolor- 

 ation spreading between the black or green rings. After the apples 

 have been exposed to the fumes for a short period, they partially 

 recover when aerated. The residual damage may be only a slight 

 skin blemish around the lenticels or it may be more serious and affect 

 the flesh tissue. 



APPLE ROTS 



Apple rots are either initially or finally caused by fungi commonly 

 referred to as molds (6, 19) or are associated with them. From 

 the standpoint of the cold-storage operator, a most important char- 

 acteristic of rot-producing fungi is that their growth and the germi- 

 nation of spores are either entirely stopped or greatly held in check 

 at temperatures of 30° to 32° F. The riper the apples are before 

 being handled the more susceptible they become to injury and rot 

 infection. The growth of such important fungi as blue mold, gray 

 mold, and Alternaria progresses slowly at temperatures of 30° to 32° 

 once infection takes place. Gradual cooling over 2 to 4 weeks is a 

 bad practice. It hastens the unseen development of rot fungi and 

 later results in a greater percentage of decay than in fruit cooled 

 quickly. 



The cold-storage warehouseman needs to keep a close watch for 

 ripening and decay in all storage lots. Certain "side rots" and the 

 "bull's-eye" rot from perennial canker are of slow growth until apples 

 reach a certain stage of ripeness, whereupon the rots grow rapidly 

 and become apparent in a few weeks, often causing severe loss before 

 being detected. Susceptible lots should be inspected frequently and 

 should be sold before becoming ripe, especially after the first signs 

 of decay are noticed. 



The effect of cold storage upon susceptibility to decay of the fruit 

 before it is washed and packed depends upon the character of stor- 

 age and the degree of ripeness of the fruit when handled. The 

 washing and packing of firm apples that are placed in good cold 

 storage promptly after harvest may take place over a long period 

 without increasing the danger from storage rots. When apples are 

 to be held at temperatures conducive to ripening, it is preferable to 

 pack them before storage unless they are to be consumed promptly 

 after packing. 



BITTER PIT 



Bitter pit, sometimes called Baldwin spot or stippen and recog- 

 nized by sunken areas or pits with brown spongy areas in the flesh, 

 cannot be controlled in cold storage. Bitter pit is a disorder related 



