CITRUS MELANOSE AND ITS CONTROL 
59 
fruit, and is found for the most part on the outside of the tree 
where the fruit is exposed to the sun. The surface tissue is killed 
and turns brown. Later it may slough off, leaving only a slight 
blemish, but usually the injury reduces the grade of the affected 
fruit. Recent developments indicate that the occurrence of this 
blemish may be reduced by the use of calcium caseinate as a spreader 
at the rate of about 1 pound to each 100 gallons of spray. 
Sulphur-spray injury. — Sulphur sprays when applied in exceed- 
ingly hot weather, especially when in combination with oil emulsion, 
may be the cause of some fruit injury. This type of injury occurs 
usually as a large spot with an irregular margin, invariably on the 
sunny side of the fruit. The affected area may be killed for a quarter 
of an inch or more in depth ; the surface becomes grayish, and later 
the dead tissue is likely to crack. (PI. 6, E.) This type of injury 
frequently develops when an application of oil spray is made during 
the summer within a week or 10 days after an application of sulphur 
dust or spray. Applications made in the reverse order seem to be 
about equally dangerous. Combination sulphur-oil sprays are also 
very dangerous when applied in hot weather. 
SPRAY SCHEDULE 
Table 15 presents a spray schedule for melanose control which is 
intended to be used only when the spring is unusually wet and con- 
ducive to melanose infection. In average seasons one application 
made between April 15 and May 5 with 3-3-50 Bordeaux plus 1 per 
cent oil as emulsion gives satisfactory melanose control. Applica- 
tion A is timed to fall in the last of the scab-spraying periods, and it 
would therefore serve a dual purpose on those forms that are suscep- 
tible to scab as well as to melanose. It is, however, too early for best 
results against melanose, and therefore a second application about a 
month later is sometimes a paying investment, but it may be omitted 
if May is dry. Under average conditions only one application is 
needed. The most effective time for this is just in advance of the 
heavy infection, which seldom occurs before May 5 (application B). 
Table 15. — Spray schedule for the control of melanose in rainy seasons 
Caution.— Spray with oil emulsion in late June or early July to control scale insects. Do not fail to control 
rust mites, otherwise the prevention of melanose is of little value because of the later russet injury. {26.) 
Application 
Time' 
Material 
Object 
A 
Apr. ltolO-.. 
May 1 to 5 
3-3-50 Bordeaux mixture 
plus 1 per cent oil, as oil 
emulsion. 2 
do. 
To protect young fruit against mela- 
B3__ 
nose; also effective against late 
citrus-scab infection. 
To protect young fruit against mela- 
nose. 
i In seasons of normal rainfall one application made between Apr. 15 and May 5 gives satisfactory mela- 
nose control. 
2 Three gallons of oil emulsion (Government formula or its equivalent) in 200 gallons of Bordeaux mixture 
gives 1 per cent of oil. 
3 This application of Bordeaux-oil emulsion will take the place of the usual white-fly spraying. 
The 3-3-50 Bordeaux mixture may be made in the usually recom- 
mended way, from stock solutions of Milestone and of quicklime. A 
more rapid and entirely satisfactory method now in general use in 
