The Palatka news and advertiser. [volume] (Palatka, Fla.) 1908-19??, 1910-11-11
-NN~NN~~~N1
STEM-END ROT OF
CITRUS FRUITS--IV :
By H. S. Fawcett.

{ By H. S. Fawcett. D
L~>~~%%<N~~A
Both Bordeaux mixture, in the usual
strength of pounds of rock lime and
pounds of copper sulphate to so gallons
of water, and ammoniacal solution OF
copper carbonate in the proportion OF 3
ounces of copper carbonate and pintS
of ammonia 26 degrees) to SO gallons OF
water, have proved effective in check
ing this disease. Spraying should be
done with the aim of hitting the fruit,
keeping the spray as much as is practi-
cable from the leaves, branches, and
trunk, where beneficial fungi may be
present
Spraying Experiments.
Although the complete results of ex-
perimentS now being carried on in six
different groves by the Experiment Sta
ton, or under its direction, will not be
al hand until the end of the picking sea-
son, the following beneficial effects
have already been noticed from the use
of either Bordeaux mixture or ammo
niacal solution of copper carbonate.
The fruit on one lot of badly diseased
grapefruit trees was sprayed three times
with Bordeaux mixture, on September
5, II, and 20. A similar lot of diseased
trees, next TO these, was left unSprayed
until September ~, when it was also
sprayed. On October IL, at which time
it was too soon for much of result
from the last spraying TO appear, ii was
found, by counting, that four times as
many fruit had dropped from those trees
which had been sprayed only once, as
from the same number of trees which
had been sprayed three times.
In a second experiment in the same
grove, ten orange trees were sprayed
with Bordeaux mixture on September
u and %, and ten similar trees next TO
them were left unSprayed. On October
II there were counted nearly twice as
many dropped fruit under the ten I'M
SPRAYED trees as under the ten sprayed
trees. Later counts are expected to
show still greater effects from the spray
ing.
Last year every alternate tree of
block of forty grapefruit trees was
sprayed twice with ammoniacal solution
of copper carbonate, on December 4,
and on December IA. On December 21
there were one-third more dropped fruit
(counted), picked up from under the I'M.
SPRAYED trees than from the sprayed
trees. Considering the lateneSS OF the
time, this was rather good showing in
favor of the spraying.
These experiments show that both the
sprays are useful in checking this dis
ease. The sprays are most effective
when used early, while the fruit is still
green; but they will do much good
even when used at this late season.
Among other experiments which are
being conducted, is a test with com
bined fungicide and insecticide, to find
out whether it can be substituted for the
Bordeaux mixture or the ammoniacal
solution of copper carbonate. 1t is de-
sirable that such a substitute should be
found, because of the damage done by
these Two sprays in allowing an increase
of scale insects.
Observations in Citrus Groves.
AS the season advances there is an
increased amount of Stem-end Rot
showing in some localities, while in
others there appears to be less than last
wear. Previous TO the storm of October
| is, in some groves as many as TO III
per cent. of the grapefruit and oranges
had already dropped from this disease.
Stem-end Rot is present and deStruc'
tive on all characters OF soil, and in
groves fortified in all sorts OF ways,
providing the fungus causing il is pres
emf. Ii is, however, noticeably worse
in low damp groves than in higher and
drier land. Although laboratory expcri'
ments show that the fungus may penc'
trate the skin of healthy fruit, obServa'
lions in the grove indicate tina those
fruits which are weakened n var the
stem by any cause, such as scale insects
are most likely TO be attacked. Even In
the grove, however, perfectly SOUND
fruit may also be attacked.
Symptoms of Stem-End Rot.
The presence of this disease is ind
Gated by the dropping of the fruit, fol
lowed by softening at the stem enc
which Softening takes place within ;
few days TO three weeks after the trui
has fallen. Only in rare cases does thu
softening at the stem end occur before
, the fruit drops. Dropping OF the frul
may, however, take place from othc
: causes, such as withertip, thorn puntures
etc. Decay of fruit may also occu
| without the presence of stem-end ROT
/ But dropping of fruit together with
large percentage of softening and deca
at The stem end, are signs OF the pres
, ence of Stem,end Rot. Sometimes
1 premature coloring at the stem end is a
indication that this part of the fruit wi
in time soften and decay, On unrip
q fruit the decay progresses rather SLOWLY
n advancing inward most rapidly along I'll
central core and the inner white part {
the peel, and finally breaking down III
Juice sacs. The diseased portion OF III
fruit becomes brownish or coffee-co
ored. In ripe fruit the discoloratio
q lags behind the softening.-PreSS Bull
lin Florida Experiment Station.