Film Box Liners 
The effect of polyethylene box liners on scald is closely associated 
with the extent to which the atmosphere is modified. Sealed polyethylene liners 
usually reduced scald and often largely controlled it, if the oxygen within the 
liners was maintained at a low level of 2 to 6 percent (29, 34, 36, 38, 49, 75, 
91, 92, 108, 110, 136). If oxygen reached an equilibrium at a higher level 
within liners, scald was not reduced and was sometimes increased (34, 49, 110, 
136). Rasmussen (87) reported higher scald for several varieties in sealed 
liners even with oxygen at a low level of 3 to 6 percent and carbon dioxide at 
6 to 8 percent. Hardenburg and Anderson (34) obtained the best scald control 
when oiled wraps or chemical scald inhibitors were used with sealed 1.5-mil 
polyethylene liners, Patterson (75) suggested that low oxygen and high carbon 
dioxide levels within sealed film liners may act synergistically in reducing 
scald. 
Nonsealed or perforated film box liners usually increase scald incidence 
(34, 36, 38, 71, 108, 110). Within these liners the atmosphere usually contains 
17 to 20 percent oxygen and 1 to 2 percent carbon dioxide (34). Ulrich and 
Leblond (130) reported no increase in scald on the Belle de Boskoop apple in 
nonsealed liners. 
Relative Humidity 
A high relative humidity of 90 percent or above is generally thought to 
favor scald development (16, 112). However, high humidity is necessary to 
minimize moisture loss so low humidity is not a practical approach to scald 
control, Recently, Hilkenbaumer (42) in Germany reported that high humidity 
(95 percent) reduced scald. 
Intervariety Effects 
The influence of one variety on the scald of other apple varieties has 
been studied by several investigators (112, 120, 124). Smock and Southwick 
(112) noted that the vapors of McIntosh apples increased scald on Cortland and 
Rhode Island Greening apples. Stoll (124) stored scald-susceptible and scald- 
resistant varieties together and found that the volatiles of susceptible varie- 
ties induced more severe scald symptoms than those of resistant varieties. The 
presence of one susceptible variety increased scald symptoms in another suscep- 
tible variety. When a resistant variety was stored with a susceptible variety, 
scald was reduced in the susceptible variety in seven out of nine tests. On the 
other hand, Stoll found that scald was induced in varieties considered resis- 
tant, if they were stored in close contact with susceptible varieties. 
Chemical Scald Inhibitors 
Many chemicals have been evaluated as possible scald inhibitors, but 
until recently none, other than mineral oil in fruit wraps, were approved for 
use, Crude bexane (44), diphenyldimethylurea (119, pp. 21-22), and growth 
regulators (93) were reported to have scald controlling properties, but they 
are not used commercially. In 1955, Smock (107) discovered the inhibitory 
effect of dephenylamine (C1 7H ,N), usually designated as DPA, which provided 
201 
