42 
BULLETIN 1474, tl. S. DEPARTMENT OF AGRICULTURE 
plus oil emulsion. " neutral " 7 Bordeaux plus oil emulsion, and a 
commercial preparation of Bordeaux mixture and oil emulsion. 
A complete list of spray materials, dates of application, and 
results obtained are given in Table 9. 
Again it will be seen that lime-sulphur solution failed to give 
any appreciable control of melanose. One and two applications of 
copper soap afforded a slight protection, and three applications gave 
a considerably greater protection but not in proportion to the cost 
involved. The same applies to 1-1-50 Bordeaux-oil emulsion and to 
a less extent to 2-2-50 Bordeaux and oil. Two and three applications 
of commercial Bordeaux-oil emulsion gave excellent results, likewise 
one or two applications of standard 3-3-50 Bordeaux and oil gave 
good commercial control of the disease whenever the spraying was 
done in advance of the May rains. 
Rainfall during the spring months of 1922. — Figure 8 shows the 
daily precipitation at Orlando during the melanose season of 1922. 
This figure shows that the spring of 1922 was unusually dry. Many 
Si 
t 
L^A 
B 
I 
/922 
■ n v m m 
8 «. 
ASs4&c/y 
u/Z//V«£" 
Fig. 8. — Rainfall (in inches) at Orlando, Fla., .during March, April, May, and 
June, 1922 
twigs died from drought effects and later became a source of melanose 
infection. The drought was broken early in May, when some infec- 
tion developed. After the middle of the month rains occurred fre- 
quently and the resulting infection was abundant. 
Copper tests. — Again copper tests were made from leaves sprayed 
with various copper materials, data from which are shown in Fig- 
ure 9. 
These findings are in accord with those of the preceding year — 
namely, that a much greater quantity of copper is found on trees 
sprayed with 3-3-50 Bordeaux and oil than those receiving sprays 
carrying smaller quantities of copper. It seems probable that a 
single application of 3-3-50 Bordeaux and oil at almost any time in 
April would afford a fair commercial control of the disease, perhaps 
better than three applications of copper soap or two applications of 
a 1-1-50 Bordeaux mixture. The 2-X-50 commercial Bordeaux and 
oil does not seem to persist on orange leaves quite as well as home- 
made 2-2-50 Bordeaux and oil. 
7 Bordeaux mixture made by pouring slowly just enough concentrated milk of lime 
into dilute bluestone solution in agitation to precipitate all of the soluble copper as 
indicated by the potassium-ferrocyanide test. This neutral Bordeaux mixture is indicated 
by a formula such as 3-X-50. 
