storage life of apples. Fisher and Porritt (21), reporting on apples in British 
Columbia, indicated that heavy applications of boron may impair their keeping 
quality. 
Preharvest Sprays 
Much of the research conducted prior to 1945 on the use of growth sub- 
stances in orchard sprays to reduce preharvest drops of apples has been re- 
viewed by Vyvyan (65). The greater part of this research was concerned with 
naphthalene acetic acid (NAA). Subsequent research revealed additional mater- 
ials that would reduce preharvest dropping. Among the more effective of these 
were 2,4-dichlorophenoxyacetic acid (2,4-D) (2, 42) and 2, 4, 5-trichlorophen- 
oxypropionic acid (2, 4, 5-TP) (19). 
Although 2,4-D remains effective longer after application than NAA, its 
usefulness is limited because it is effective primarily on Stayman Winesap (27, 
28) and Winesap (2, 4, 28). Both NAA and 2, 4, 5-TP effectively reduce drops 
on many varieties but 2, 4, 5-TP remains effective longer after application than 
NAA (19, 30). Aside from their drop-reducing abilities, both NAA and 2, 4, 5-TP 
have elicited variable responses on maturation, ripening, coloring, softening, 
and storage quality of the fruit. 
Gerhardt and Allmendinger (22) did not find that NAA increased ripening 
or impaired storage quality of either Delicious or Winesap apples if the fruit 
was harvested within 2 weeks of the spray application. They later (23) empha- 
sized the importance of picking the fruit within the recommended picking time 
for the variety, to avoid the possibility of increased ripening due to this 
spray. Marshall and his co-workers (38) did not find ripening to be increased 
by sprays of the methyl ester of NAA on Delicious, McIntosh, or Wealthy apples 
during 65 days" storage at 33° F. Others too, have reported no apparent effects 
on ripening or keeping quality as a result of preharvest sprays of NAA on apples 
(34, 64, 66, 67). Padfield (45) and McKenzie (39), on the other hand, reported 
a deterioration of storage quality on Granny Smith and an increase in storage 
losses of Jonathans when these fruit received preharvest sprays of NAA. Steven- 
son and Dodd (59) compared the effects of NAA and 2, 4, 5-TIP on the storage 
life of Delicious and found NAA had an unfavorable effect on storage due mainly 
to the occurrence of greater amounts of superficial scald. Batjer and Moon (3) 
found that NAA stimulated ripening in such summer varieties as Close, Williams, 
and Duchess of Oldenburg but had no direct effect on ripening of such later 
varieties as Delicious, In 1949 Southwick (54) showed that methyl a-naphthalene 
acetate was capable of stimulating respiration, softening, and ground color 
changes in preclimacteric apples held at room temperature. Once the preclimac- 
teric has passed though, he indicated, the fruit may not show such a response 
to this material, 
A stimulation of the maturation and ripening processes or the possible 
reduction in storage life attributable to 2, 4, 5-TP has been recorded by a 
pumbersofeinvestigators (6), 13 34) 365 50), '55),)25649160 1 s6is1c62 ic) However, some 
of these same investigators, as well as others, have not always found that 2, 4, 
5-TP stimulated such processes or reduced the storage life of the fruit (5, 9, 
a Lan Lon 6, 26% 295-315, 35, 41, oll), 2p Wardietalirditterences:may im «pant 
account for some of these conflicting observations. Thompson (61, 62) found 
that sprays of 2, 4, 5-TP stimulated ripening of summer varieties but had little 
or no effect on fall and winter varieties, results similar to those reported by 
Batjer and Moon (3) with NAA. Smock, Edgerton, and Hoffman (53) also reported 
69 
