| Material Information
||Stem-end rot of citrus fruits--III
||2 leaves : ; 21 cm.
||Fawcett, H. S ( Howard Samuel ), b. 1877
University of Florida -- Agricultural Experiment Station
||Florida Agricultural Experiment Station
||Place of Publication:
||Citrus -- Diseases and pests -- Florida ( lcsh )
Fungal diseases of plants -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||by H.S. Fawcett.
||"September 13, 1910."
| Record Information
||University of Florida
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 78474701
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
PRESS BULLETIN 154
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
STEM-END ROT OF CITRUS FRUITS-IIl
By H. S. Fawcett
This is the time of year when a recurrence of this trouble may be looked
for in groves which have been previously affected by this disease. A small
amount of dropping and decay of green fruit has already been noticed in one
locality where the stem-end rot was prevalent last year. Microscopical exami-
nations show that the same fungus is present there which was proven to
be the cause of the injury last year.
The presence of the disease is indicated at this time of year by premature
dropping of the fruit, and by a softening at the stem end, which takes place
from a few days to three weeks- after the fruit has fallen. Only in rare cases
does the softening at the stem end occur before the fruit drops. Dropping of
fruit may, however, take place from other causes, such as withertip, or lack
of moisture. Decay of fruit may also occur without the presence of the stem-
end rot. But dropping of fruit together with a large percentage of softening
and decay at the stem end, are signs>of the presence of stem-end rot. Some-
times a premature coloring at the stem end is an indication that this part
of the fruit will in time soften and decay. On unripe fruit, the decay pro-
gresses rather slowly, advancing inward most rapidly along the central core
and the inner white part of the peel, and lastly breaking down the juice sacs.
The diseased portion of unripe fruit becomes brownish or coffee-colored. In
ripe fruit the discoloration lags behind the softening.
Suggestions As to Treatment
Spraying experiments conducted by the Experiment Station last year for
the control of this disease were started late in the season. The results, how-
ever, indicate that either ammoniacal solution of copper carbonate or Bordeaux
mixture may be used with advantage in'checking the disease. (These sprays,
however, cannot be employed without serious injury to the 'whitefly fungi
when they are present in a grove.) Since the disease is infectious, all dropped
and decayed fruit should be taken from the grove and destroyed.
September 13, 1910
The direct cause of-this decay has been shown to be the growth of a
species of fungus in the tissues of the orange. This fungus parasite is of
microscopic size, and usually enters the fruit at the stem end. Experiments
have shown that oranges begin to show decay in from one to three weeks after
artificial infection with the fungus.
Studies of this disease and of the fungus causing it have, so far, brought
out the following facts:
1. Sound citrus fruits were infected by placing on them pieces of diseased
2. Sound fruits were infected by placing on them pure cultures of the
fungus isolated from decayed fruit.
3. Sound fruits were infected by placing them in water for a few hours
along with soil from under infected trees.
4. Cultures of the fungus were obtained from the soil, as 'well as from
the diseased fruit.
5. The fungus lived for three months in air-dried soil in the laboratory.
6. The fungus grew well in either acid or alkaline media.
Information and Specimens Wanted
As the writer wishes to find out as much as possible about this disease, he
will appreciate it if the growers will send in specimens of infected fruit with
information as to the severity of the disease. Any one sending specimens will
be privately Informed as to the presence or absence of the disease. Send to
"Plant Pathologist, Florida Experiment Station, Gainesville, Florida."
,State papers please copy.