38 
BULLETIN 1474, U. S. DEPARTMENT OF AGRICULTURE 
the month, while in April there was an excessive quantity of rainfall 
to the extent of 4.7 inches above normal, but there were only a few 
rainy days. This resulted in very little infection before May 5, 
and from then on several rains fell and much more infection occurred. 
SPBAYING EXPERIMENTS IN 1921 
In 1921 the spraying experiments were conducted in the same 
seedling orange grove at Orlando which had been used the preceding 
year. Thirty-eight plots were sprayed, each receiving from one to 
three applications of fungicide. The following spray materials 
were used: Lime-sulphur solution, dry lime-sulphur, barium tetra- 
sulphide, a commercial form of self-boiled lime-sulphur, Pritchard 
and Clark's (17) copper soap, 3-3-50 Bordeaux mixture plus 1 per 
cent oil as emulsion, 1-1-50 Bordeaux mixture plus 1 per cent oil, and 
a commercial Bordeaux powder in proportions to give 3-3-50 
Bordeaux mixture to which 1 per cent oil as emulsion was added. 
2.4 
2.2 
2.0 
\<* 
> /.2 
N 
X/.O 
|- 
Fig. 6. — Rainfall (in inches) at Orlando, Fla., during March, April, May, and 
June, 1921 
The list of spray materials, dates of application, and results 
obtained are given in Table 8. 
From Table 8 it is obvious that sulphur sprays as a class are prac- 
tically worthless for melanose control, and that copper soap and the 
weaker strengths of Bordeaux mixture are only partially effective. 
Stronger Bordeaux mixture applied about the first of May gave very 
good control of melanose, but applications made after the middle 
of that month were decidedly less effective, and those in June had 
little or no effect on the disease. The added protection resulting 
from the second and third applications is not sufficient to justify 
more than one application. 
Rainfall during the spring months of 1921. — In order to aid in 
determining the effect rainfall may have had on the efficacy of the 
sprays, the precipitation record at Orlando during the melanose 
season of 1921 is shown in Figure 6. It is seen from this figure that 
very little rain fell during March and April, and May was dry until 
about the 13th of the month, when rains set in and lasted for 12 
