MARKET DISEASES OF APPLES, PEAES, QUINCES 45 



The disease is characterized by peculiar patches and ribbonlike 

 areas of brown tissue on the surface of the apple and by the sharp 

 line of demarcation between the diseased and healthy tissue (pi. 5,F). 

 Sometimes only the skin of the apple is affected, but more often the 

 browning extends into the flesh for an eighth of an inch or more. 

 Black spots on areas injured by soft scald (pi. 5,. C) are usually 

 caused by secondary infection with Cladosporium or Alternaria. 



Soft scald is apparently due to abnormal respiratory conditions in 

 the apple. It is much more likely to develop at temperatures that 

 border on the freezing point of apples than at those a few degrees 

 higher, and is greatly increased by delay in placing the fruit in 

 storage. 



Oiled paper does not control soft scald. Applying a thin coating 

 of paraffin to the fruit decreases the disease. Holding the apples 

 in an atmosphere containing 20 to 30 percent of carbon dioxide for 

 2 days during the period of cooling has largely or entirely prevented 

 the later development of soft scald. {22, 28, 62, 100, IJfi, 178, 179, 

 180, 195,) 



SOGGY BREAKDOWN 



Soggy breakdown is a functional disease of apples that some- 

 times has been included under internal breakdown but appears to be 

 distinct both as to characteristics and cause. Grimes Golden, 

 Wealthy, and Golden Delicious are very susceptible to the disease, 

 whereas Arkansas (Mammoth Black Twig), Willowtwig, and North- 

 western Greening appear to be immune. 



Soggy breakdown is first evident as light-brown areas in the cor- 

 tical region of the apple. The discoloration may continue until a 

 large part of the cortex is involved and a complete ring of soft 

 brown tissue formed (pi. 5, D). The affected flesh is sharp 1}^ defined 

 from the normal and is typically moist and soggy, although some- 

 times becoming mealy in advanced stages of the disease. The ad- 

 jacent sound tissue usually has a characteristic fermented taste. 

 The skin of the apple may appear normal except in the later stages 

 of the disease, but affected fruit can be detected by a characteristic 

 sponginess, due to the underlying soft tissue. 



Soggy breakdown is akin to soft scald in the conditions responsi- 

 ble for its occurrence. It is more prevalent on apples stored at 30° 

 F. than on those held at 32° and is usually completely prevented 

 by storage at 36° to 40°. It is generally increased greatly by de- 

 layed storage. 



Holding the apples in an atmosphere containing 20 to 30 percent 

 of carbon dioxide for 2 days during the period of cooling has largely 

 or entirely prevented the later development of soggy breakdown. 

 {27a, 177, 178, 181, 182.) 



SOOTY BLOTCH 



(Gloeodes pomiffena (Schw.) Colby) 



Sooty blotch is marked by sooty patches or spots, very irregular 

 in size and shape, which may occur on any part of the apple (pi. 3, 

 C, E) . They are easily removed by scraping with the finger nail or 



