MARKET DISEASES OF APPLES, PEARS, QUINCES 33 



Internal breakdown is at times mistaken for freezing injury. In 

 distinguishing between the two it is of assistance to bear in mind that 

 a large part of the browning in frozen apples occurs at bruises ex- 

 tending inward from the surface (see Bruises, p. 16), and that freez- 

 ing injury may occur at any point on the apple without relation to 

 maturity or morphology. On the other hand, the browning from 

 internal breakdown at a bruise rarely assumes a radial direction, is 

 usually accompanied by a greater degree of mealiness, and includes 

 more of the surrounding tissue. 



Internal breakdown occurs most often on large-size overmature 

 apples and on those that have been forced late in the season. It is 

 sometimes the result of holding the fruit on the trees too long, wait- 

 ing for color, and can often be traced to delay in cooling the fruit 

 after it has been harvested or to the fact that the fruit has been held 

 in storage at too high a temperature or beyond its proper season. 

 Internal breakdown also often follows water core, as previously 

 noted, and for this reason it is usually considered hazardous to store 

 water-cored apples. The amount and seriousness of internal break- 

 down varies from year to year, apparently being dependent to a large 

 extent upon growing conditions. 



The little that can be done to control internal breakdown after 

 picking is best done by handling promptly into cold storage at 31° 

 to 32° F. Breakdown is particularly serious in common storage, but 

 fruit with a decided tendency toward it cannot be relied on for late 

 keeping even in cold storage.' (22, J^S, 62, 80, 100, 162, 172, US, 17Jf, 

 179, d80, 186, 195.) 



INTERNAL BROWNING 



Internal browning is a nonparasitic storage disease that is decid- 

 edly regional in its occurrence. It is particularly serious in Yellow 

 Newtown apples grown in the Pajaro Valley in California, and also 

 occurs in Yellow Bellflower and other varieties from that sec- 

 tion, which has cool, cloudy, or foggy weather through the grow- 

 ing season. It is occasionally found in Yellow Newtown from other 

 States, notably Washington, Oregon, Virginia, and New York, and 

 in Rhode Island Greening from New York. 



Internal browning differs from internal breakdown in the fact that 

 the affected tissues are not soft and also in the further fact that the 

 browning first appears as somewhat elongated areas usually radiat- 

 ing out from the central portion of the apple and from the primary 

 vascular bundles (pi. 8, C, D). The outer fleshy portion of the apple 

 may also show radiating lines of brown tissue, but this condition is 

 usually accompanied or preceded by the more prominent develop- 

 ment around the core, shown in plate 8, B. Internal browning does 

 not manifest itself by any abnormal appearance of the skin of the 

 apple, and the disease can be detected only by cutting into the fruit. 



Internal browning apparently has a close relationship to soft scald 

 and soggy breakdown in the conditions responsible for its occurrence. 

 The usual cold-storage temperatures (31° to 32° F.) are particularly 

 favorable to its development, and control can best be secured by 

 storing the apples at a temperature of 36° to 40°. However, the 

 tendency to develop internal browning is inherent in the fruit when 

 it comes from the tree. Low temperatures during the growing 



181541°— 33 3 



