MARKET DISEASES OF FRUITS AND VEGETABLES 37 



Hail injury can be distinguished from other spots described 

 by the fact that only the upper exposed part of the fruit is 

 affected. This usually coincides with the blushed area, unless 

 fruits are injured by hail while still young and small. 



Heat Injury 



Apples may be injured while still on the tree by excessively 

 high temperatures following a period of relatively cool weather. 

 Heat injury is greatly influenced by soil moisture and is most 

 likely to occur when the high temperature is accompanied by a 

 sudden deficiency of soil moisture. The injury usually occurs on 

 the exposed side of an apple and frequently at the margin rather 

 than at the center of the most exposed area. 



On slightly injured fruits the only symptom consists in isolated 

 spots of brown spongy tissue, but on those injured to a greater 

 extent the tissue may be in various stages of partial collapse. 

 Sometimes an entire fruit looks as if it were completely baked. 

 The following symptoms, however, are more likely to be seen on 

 fruit on the market. The skin usually retains its normal appear- 

 ance, but it may be of a deeper color than normal, sunburned, or 

 even killed and brown. There is always some form of tissue 

 collapse under the affected area, so that the surface often becomes 

 sharply sunken (pi. 3, G, H). Such collapsed tissue often makes 

 the fruit knobby or distorted. The extent of collapse depends 

 upon the severity of the injury. The surface of the injured area 

 may be wrinkled, depressed, or corrugated. Depressed areas are 

 often crescent-shaped. The brown spongy tissue below the sunk- 

 en surface may have irregularly shaped cracks or cavities. 



(See Ik.) 



HONEYDEW AND SOOTY MOLD 



Honeydew on apples is deposited by aphids and certain other 

 sucking insects. This sticky substance is a favorable medium 

 for the growth of sooty mold, which sometimes covers much of 

 the surface of the fruit. Although this mold is superficial and 

 usually does not affect the internal condition of the fruit, it 

 detracts from its appearance. 



Internal Break-Down 



Internal break-down occurs in apples grown in all of the fruit- 

 growing sections of the United States. It has been observed most 

 often in Jonathan, Stayman, Rome Beauty, Wagener, and certain 

 summer varieties that quickly become overripe; but Delicious, 

 Esopus Spitzenburg, Yellow Newtown, Baldwin, Winter Banana, 

 and Rhode Island Greening are also frequently affected. 



Internal break-down often indicates the end of the storage life 

 of apples when they are not affected by fungus rots. It may, 

 however, occur earlier as a result of unfavorable growing con- 

 ditions or certain handling or storage practices and may follow 

 water core, freezing, or bad bruising. It is characterized by the 

 breaking down and browning of the interior of the apple (pi. 9, 

 H), sometimes only on one side or around a bruise and at other 

 times throughout the fiesh. Often an outer shell of healthy flesh 

 about 14 mcn thick surrounds a brown zone that in cross section 



