6 DEPARTMENT CIRCULAR 409, U. S. DEPT. OF AGRICULTURE 
Figure 2 
made during the six-year period 1920-1925. 
shows the total rot in unweighted averages of all tests 
As has been indicated, the experiments were planned the first two 
years to include a relatively large number of tests during the rainy 
season and later. 
The interval between dates of spraying for suc- 
cessive plots was usually 10 days, but sometimes was as long as 15 
days. 
A proper weighting of the averages would compensate for 
irregularities in the number of oranges in the samples as well as for 
the variations in numbers of tests included in the several periods and 
iN CO? AF 
Vso EZ 
. peniciess tng ks 
ANNO SVISCELL. AS, 
X LEZ 
WD ae 
WNtint 
WW 
C7 <o 0° SX 
LES SES So SSS OS S505 ses 
SOIL 22, Legs <<] 
xS G: SOs SSS Sse Senet SPSS SoS SESS 
Zi SOK SOO RO xk oS KS SXRD S59 ROXe 
18 @4 &P > IO FF 
QaAYS 
LZ 
Fie. 3. —Proportions of various rots based on total oranges 
originally in the test, not sprayed, held 36 days. The 
percentages are based on collections made from a single 
old seedling-tree grove during five years, 1921-1925 
for the several sea- 
sons; but the form 
presented suffices for 
a practical showing 
of how general keep- 
ing quality of the 
fruit is affected by 
single applications 
made at various 
times and over a 
term of years of 
what has proved to 
be the most effective 
available fungicide. 
The best results came 
from spraying dur- 
ing the period ‘of best 
melanose control, 
April 15 to May B. 
Spraying before this 
period gave better 
results than spraying 
after it, which also 
agrees with the re- 
sults obtained in mel- 
anose control. Very 
little benefit came 
from spraying in 
summer or fall. 
The general conclu- 
sion is that a spray 
application properly 
timed for melanose control 1 is the most effective for reduction of total 
rot after the fruit is picked. 
EFFECTS ON VARIOUS ROTS 
The proportionate amount of each constituent rot is shown in 
Figure 3 for unsprayed oranges and in Figure 4 for oranges sprayed 
once with 3-38-50 Bordeaux-oil April 15 to May 5. These graphs 
are based on the results of five seasons, 1921 to 1925. Since condi- 
tions influencing rot development and effectiveness of control 
measures varied from year to year, and since the number of tests 
and the amount of sampling also varied, it has seemed best to deter- 
mine the average results for each season and to give these seasonal 
