The Palatka news and advertiser. [volume] (Palatka, Fla.) 1908-19??, 1911-02-24
crescent City News
The Treatment Of MeIanose.
BY Ii. + FLOYD

Wnere The citrus crop was considera-
bly, injured by melanose during the sum
merS of the last two years, it is advisable
TO spray during the spring of 1911.
Spraying with either Bordeax mixture or
ammoniacal solution OF copper carbonate
will prevent this injury. Two sprayings
should be made; the first about two
weeks after the flowers have fallen; and
the second, four weeks later. A nozzle
OF 10 degrees angle should be used for
applying the spray. With such nozzle
the solution can be directed downward,
thereby preventing, more or less, the
wetting of the under surfaces OF the
leaves where the friendly fungi thrive
on the scales and whitefly.
Wherever il is found necessary 10
spray for the prevention of melanose,
the grove should be carefully inspected
at short intervals. If scale insects show
any tendency TO become abundant, they
should be kept in check by the use OF
some good inSecticide until the friendly
fungi have developed again.
CAUSE OF MELANosE
From our most recent investigations
il is concluded that melanose is not
disease which is due to malnutrition;
but that it is caused by some unknown
organism. Some of the reasons for this
conclusion are as follows:
1. The markings that the disease
makes upon the fruit, stems and leaves
are superficial. They extend to only
small distance beneath the skin, and are
separated from the healthy tissue by
layers of cork tissue.
2. The markings are small and indi-
yidual. They have no connection with
each other, excepting where they occur
so close together as to unite in patches.
3. The disease Injuries the tree by
affecting the functioning of the outer
tissues, such as the breathing pores, and
the cells containing the green of the
plant.
4. Only young succulent tissue be-
comes infected. The place of infection
is mere point that increases in size
with the growth OF the affected part
5. The distribution of the disease
throughout the tree and through the
grove is much like that of diseases
which are known TO be caused by para
site organisms.
&. The disease is found on all varie-
ties of citrus fruits. 1t affects trees grow
ing under opposite conditions, such as,
trees that are starved, and trees that are
well-fed; trees growing on acid soils,
and trees on alkaline soils; trees growing
on hammock soil, and trees on high
pine land.
l. Any condition or treatment that
tends TO reduce the vitality of the tree
makes it more susceptible to the disease.
Trees that are affected with other dis
eases, such as gummoSiS, blight, yellow
spotting, and Scaly bark, are particularly
susceptible. Trees that have been in
iured by cold are easily infected. Data
at hand show the disease TO be more
prevalent north of the frost line; but
il is not all confined to this region. At
tempts have been made TO cure the dis
ease by the application of fertilizers.
These were doubtless of benefit by
making the tree less susceptible to in
fiction.
s. In some cases the disease is asSo-
ciated with dead wood in the tree. II is
probable that the dead wood is source
of infection.
SYMPTOMS OF MELANOSE
The markings that melanose makes
upon the fruit, stems and leaves are es.
sentially the same. They consist OF
groups of gum filled cells that have been
cut off and raised from the healthy tissue
of the plant by corky tissue.
The markings start as sunken points In
the young Succulcnt tissue, and these
grow larger and more evident as the
tissue grows older. They become ele-
waited and wax-like and reddish brown
in color in their mature condition:
They somewhat resemble drops OF
melted sugar burned TO reddiSh-brown
color.
The markings are in most cases scat
tered like pepper over the affected sur,
face. Often patches of them will inter
lace, surrounding little fields of green
They are sometimes arranged in circles
or parts of circles. This is characters
tic symptom.
In most cases, the damage done TO the
leaves and stems is negligible. But
when the fruit is marked by the dis
ease, its market value is reduced, and II
NAV be a total loss Press Bulletin No
165, Agricultural Experiment Station.