CITRUS MELANOSE AND ITS CONTROL 
51 
From these results it is evident that some groves were much better 
protected than others. The maximum protection obtained was 98 
per cent, whereas the minimum protection was only 10 per cent. 
This variation is to be expected and seems due largely to difference 
in thoroughness of application, as it is known that the two groves 
with the least control were not thoroughly sprayed. In some in- 
stances, especially on large properties, spraying was not completed 
until long after heavy infection had taken place. In general, how- 
ever, melanose control was very satisfactory, and for the most part 
scale insects did not become abundant during the summer because in 
nearly all of the groves a special application of oil spray was made 
in late June. In one or two groves this summer oil spray was omit- 
ted, resulting in serious damage from scale insects. 
In most instances the unsprayed checks were a part of the sprayed 
groves, but occasionally near-by unsprayed groves of a like age and 
general condition were used for checks. Typical scenes in groves 
sprayed commercially are shown in Plate 10, B, C. The combined 
results of these tests are given in Table 12. 
Table 12. — Combined results of commercial spraying for melanose control on 
orange and grapefruit groves at various points in Florida, in 1922 
Treatment 
Variety 
Num- 
ber of 
Melanose infection 
Absent 
Very 
slight 
Slight 
Me- 
dium 
Severe 
Very 
severe 
Sprayed 
Unsprayed. 
Sprayed 
Unsprayed. 
Sprayed — 
Unsprayed. 
Orange. 
do.. 
Grapefruit 
do : 
Orange and grapefruit. 
do 
Per cent 
64 
1 
59 

61 

Per cent 
23 
15 
21 
2 
21 
Per cent 
9 
14 
10 
6 
10 
Per cent 
3 
27 
Per cent 
1 
27 
3 
Per cent 

16 
1 
51 
1 
41 
Again there is considerable evidence to show that the orange is 
less susceptible to melanose than is the grapefruit, and, as would be 
expected., melanose control was more complete on the former than on 
the latter. Comparing the sprayed fruit with the unsprayed, there is 
a marked reduction in the percentage of blemished fruits as well as a 
reduction in the degree of injury oh the sprayed fruit. 
The weather throughout the citrus belt in the spring of 1922 was 
about normal as regards rainfall during March, but April was very 
dry, bordering on drought in many sections, and May was very wet 
and conducive to melanose outbreaks, especially after the 10th or 12th 
of the month. 
Commercial spraying in 19*23. — In 1923 a still larger number of 
groves were sprayed commercially with Bordeaux mixture and oil 
emulsion for the control of melanose, and counts were made in places 
throughout the citrus belt. Counts were made at points from Jupiter 
to Hastings along the east coast, at various points throughout the 
central part of Florida, and from Sutherland to Fort Myers along 
the west coast. The results of these counts of commercial spraying 
for melanose control on oranges and on grapefruit in 1923 are shown 
in Figures 14 and 15. 
