Material Information

Series Title:
Press bulletin
Stevens, H. E ( Harold Edwin ), b. 1880
University of Florida -- Agricultural Experiment Station
Place of Publication:
Florida Agricultural Experiment Station
Publication Date:
Physical Description:
2 leaves : ; 23 cm.


Subjects / Keywords:
Citrus -- Diseases and pests -- Florida ( lcsh )
Fungal diseases of plants -- Florida ( lcsh )
Fungicides ( jstor )
Fungi ( jstor )
Infections ( jstor )
government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )


General Note:
Caption title.
General Note:
"April 4, 1914."
Statement of Responsibility:
by H.E. Stevens.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
84957708 ( OCLC )


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Full Text




Melanose is one of the commonest citrus diseases in Florida.
It occurs in all citrus-growing localities in the State. All varie-
ties of citrus are attacked, the young shoots, leaves, and fruits
being affected. The greatest loss is due to the unsightly mark-
ings produced oi the fruits. Melanose is easily recognized, and
is known to most growers. The disease is responsible, no doubt,
for a considerable dropping of young fruits, especially if a heavy
infection takes place early in the season. Melanose and Stem-
End Rot are caused by the same fungus (Phomopsis citri), as has
been pointed out in Bulletin 111. This fungus lives and repro-
duces itself chiefly in the dead twigs and branches of citrus trees.
This dead wood containing the fungus forms the source from
which repeated infections take place, whenever favorable weath-
er conditions occur.
The most important step in controlling this disease is to re-
move and destroy the cause. Trees should be kept free from
dead wood. All dead branches and twigs should be pruned out
and burnt each year. Pruning should be done during the winter
months, or before the first flush of growth in the spring. This
will to a considerable extent protect the new growth which is
often badly infected early in the season. Summer pruning should
be done where the trees are not pruned during the winter. The
results of our pruning experiments this year show that nearly

April 4, 1914

three times as much fruit free from Melanose was obtained from
trees carefully pruned, as was obtained from trees not pruned.
It should be remembered that this year's crop was very lightly
affected by Melanose.
Where the grower has not pruned, in order to protect this
season's crop he may spray with some fungicide. Webber and
Swingle state that Melanose was controlled by spraying twice
with Bordeaux mixture. The first spraying was'made just after
the bloom dropped; and the second one, one month to six weeks
later. A third spraying may be advisable, and should be applied
about one month after the second. Ammoniacal solution of
copper carbonate will give about the same results as Bordeaux,
and may be used if preferred.
In using any fungicide on the citrus tree, the grower must be
prepared to combat the scale insects that follow. The applica-
tions of fungicide should be followed by some good contact in-
The indications at present point to a heavy Melanose infec-
tion this season. There has been an unusual development of the
fungus in the dead citrus wood during the fall and winter months.
Dead twigs have been examined from groves in a number of
localities, and these have been found to contain an enormous
number of fruiting bodies of the fungus. With so much of the
fungus present, should favorable weather conditions prevail for
a few days, the injury from Melanose to this season's crop will
be enormous. The heaviest infections of Melanose usually de-
velop after rains which are followed by three or four days of
cloudy weather.
The leaves and young shoots are only subject to infection for
a comparatively short period-a month to six weeks. Infection
on fruit may take place any time after the bloom has dropped
until the fruit is two-thirds or more mature. Our experiments
show that fruits which dropped the bloom in March could be in-
fected with Melanose as late as July.
State papers please copy.