10 CIRCULAR 740, U. S. DEPARTMENT OF AGRICULTURE 



APPLE SCALD 



Apple scald is a browning of the skin and is distinguished from 

 soft scald by being superficial and generally diffuse, and from a simi- 

 lar superficial browning following washing injury by being more 

 localized and more pronounced on the green or unblushed surfaces. 

 It is associated with fruit harvested at an immature stage and may be 

 entirely prevented in some varieties, including Delicious, by delaying 

 picking until the fruit is sufficiently mature. It is induced by certain 

 volatile products of respiration, and if apples are not too immature 

 when harvested it can be largely controlled by placing paper con- 

 taining at least 15 percent of an odorless and tasteless mineral oil in 

 contact with the fruit as soon as possible after harvest. When 

 shredded oiled paper is used, at least half a pound per bushel is neces- 

 sary and it should be well distributed so as to be in contact with every 

 apple. 



Where practical considerations dictate the storage of loose fruit 

 for extended periods, scald prevention calls for (1) fruit adequately 

 mature when picked and (2) active air movement over it. The use 

 of slatted crates or orchard boxes and adequate spacing of containers 

 in storage is beneficial. Apple scald ordinarily does not begin to 

 appear earlier than 60 days after harvest, and the more mature the 

 apples when picked the later its appearance. When it begins to 

 appear, the fruit should be disposed of, as the scald is likely to spread 

 and become more intense, especially after the apples are taken out into 

 living-room temperature. Scalded fruit frequently arrives at the 

 market in bad condition, with rots starting in the scalded tissue. 



SOFT SCALD AND SOGGY BREAK-DOWN 



Soft scald is frequently confused with apple scald but has a differ- 

 ent appearance and is radically different with respect to cause and 

 prevention. Soft scald seldom occurs on fruit picked at the proper 

 stage of maturity and stored immediately at 30° to 32° F. It is usu- 

 ally caused when susceptible varieties of apples are delayed at warm 

 temperatures after harvesting and are then placed in low-temper- 

 ature storage (below 36° ) . It cannot be prevented by the use of oiled 

 paper or by picking at an advanced stage of maturity. 



In its early stages soft scald may resemble apple scald, as faint 

 patches of brown become apparent, but soft scald develops rather 

 rapidly into slightly depressed areas of discolored skin. The mar- 

 gins of the affected areas are sharp, and the pattern is generally irreg- 

 ular. The apple may have the appearance of having been rolled 

 over a hot stove. Another distinguishing feature is the brown spongy 

 tissue beneath affected areas. In certain varieties the disorder may be 

 confined to the small points of contact where apples press against 

 each other. When limited to this type of manifestation, soft scald is 

 sometimes referred to as "contact scald" and when found in midwinter 

 it rarely develops to greater proportions. 



Jonathan and Rome Beauty are the varieties most susceptible to soft 

 scald. At the expense of a shortened storage life these varieties should 

 be stored at 36° to 38° F. if they cannot be given 30° to 32° within 24 

 hours after picking. The same applies to Golden Delicious if not 



