May 31,1924 
Borax Treatment of Citrus Fruits 
965 
including Valencias in their prime and seedling oranges that were dead ripe. 
There is a distinct reduction in all three rots, Phomopsis and Diplodia stem-end 
rots showing decided reduction as well as blue-mold rot. This reduction in stem- 
end rots was an entirely unexpected outcome of the experiment. One possibility 
is that the borax solution may 
penetrate and disinfect the 
calyx edges or other portions 
of the button in which these 
two stem-end rot fungi are 
established, and from which 
they later extend their growth 
into the stored fruit. 
Two commercial shipments 
of boxes of oranges and of 
grapefruit were made, one 
during April and one in May, 
1924, from points in Florida 
in regular fruit cars under re¬ 
frigeration to Seattle, Wash., 
and by ordinary express to 
Washingon, D. C. Not enough 
blue-mold rot developed in 
either the treated or the un¬ 
treated fruit for definite show¬ 
ing, even during a holding 
period of several weeks dura¬ 
tion after arrival. The boraxed 
fruit in these shipments again 
showed a distinct reduction of 
stem-end rot when compared 
with the controls. Further 
tests will be made to deter¬ 
mine the effect on blue-mold 
rot of the borax treatment in 
commercial shipments. 
The question arose as to 
whether increasing the strength 
of the borax solution would 
give better control. At ordi¬ 
nary air temperature water 
saturation occurs at about 6 
per cent or 7 per cent of borax, 
but solubility increases rapidly 
with rise in temperature. At 
85° F. it is approximately 7 
& /e 
Fig. 4—Percentages of blue-mold rot developing in citrus fruit 
treated with 5 per cent and with 10 per cent borax solution 
and untreated during 21 days 
0 & & & /2 /<3 £/ 
per cent; at 113°, approxi¬ 
mately 14 per cent; and at 
122°, approximately 18.5 per 
cent. In California lemons 
and oranges are usually washed for several minutes in water between 115° 
and 120° for control of brown rot without bad effect. In the warm-water 
tests the writers have used 10 per cent commercial borax in water maintained at 
122°, on plump but not turgid fruit that had been off the trees at least 10 days 
when purchased from the market. Seven tests, two with oranges and five 
with lemons, are averaged in figure 4. The percentages of rot are based on 
