Bio

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Fungal Diseases of Banana
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Sigatoka leaf spots
Yellow Sigatoka caused by Mycosphaerella after
the Sigatoka Valley in Fiji where an outbreak of
this disease reached epidemic proportions from
1912 to 1923.
Black Sigatoka, also known as black leaf streak,
was named for its similarities with the Yellow
Sigatoka
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Symptoms
Sigatoka leaf spots
Initially, tiny brown streaks appear on the
underside of the third and fourth leaves.
After the streak stage, spots develop. These
spots increase in size and gradually turn brown
in color.
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Symptoms
Sigatoka leaf spots
When the disease progresses these spots further
increase in size, join with each other forming
large dead areas on the leaf preventing
photosynthetic functioning of the leaf.
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Symptoms
Sigatoka leaf spots
Destruction of mature and functional leaves in
large number leads to failure of bunches to fill
out and ripen.
Fruit set will be poor with reduced size, uneven
ripening and angular shape having discolored
flesh.
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Spread of disease
Sigatoka leaf spots
The fungus produces conidia and ascospores, both
of which are infective.
They are formed under high moisture conditions,
and are disseminated by wind, and in the case of
conidia, also by rain and irrigation water.
Infected planting material and leaves, which are
used often as packing materials, are usually
responsible for the long-distance spread of the
disease.
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Spread of disease
Sigatoka leaf spots
Humid weather and high rainfall periods hasten
the development and faster spread of the disease.

Under a crowded canopy and humid condition, the
conidia rapidly spread the disease on to a
susceptible variety.
Soils with poor drainage and low fertility are
more conducive for disease build up.
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Management
Sigatoka leaf spots
The suckers brought for planting should be
disease free. They should be dipped in a
fungicide solution before planting.
Proper, wider spacing must be practiced. The
orchard must be clean and free from weeds and
grasses to avoid humidity build up.
Severely infected plants and leaf blades should
be removed and destroyed.
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Management
Sigatoka leaf spots
Periodical roguing of diseased leaves reduces the
spread of the disease.
The land should be well drained and leveled to
avoid any water stagnation.
Application of Thiophante methyl 1 g/l or
bordeaux mixture 0.1 per cent 2 per cent
linseed oil or captan 2 g/l can manage the yellow
sigatoka disease.
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Management
Sigatoka leaf spots
One of the following fungicides also can be
sprayed.
Carbendazim 1 g/l
Benomyl 1 g/l or Mancozeb 2 g/l
Copper oxychloride 2.5 g/l
Ziram 2 ml/l
Chlorothalonil 2 g/l
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Anthracnose
It is an important post-harvest problem of
bananas especially during transport and storage.
Infection in young fruit is not always manifested
until the fruit ripens,
Pulp of diseased fruit is usually not affected
unless the fruit is over-ripe.
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Anthracnose
Symptoms
On green fruit, pin-size brown or black sunken
spots develop. The peel has dark-brown to black
diamond-shaped lesions about 8 x 3 cm in size.
The centers of the spots become dark because of
the formation of small black fruiting bodies of
the fungus.
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Anthracnose
Symptoms
On yellowing fruit, brown spots initially appear
that later become sunken and covered with orange
spore masses.
A tip rot may develop and can rot the entire
fruit but the pulp is usually not affected unless
the fruit is overripe.
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Spread of disease
Anthracnose
Anthracnose spreads to banana plants by wind,
insects, water and birds.
The fungus thrives in heavy rainfall and
temperate weather conditions.
The fungus that causes anthracnose also causes
crown rot, another rot-disease of banana.
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Management
Anthracnose
Practice good field sanitation.
Minimize bruising during fruit handling.
Treat the fruit with hot water for 5 min at 50C.
Proper sanitation of handling facilities
Sprays of jathropa oil extract at 5000 ppm (5 ml
of oil extract in 5 litres of water)
significantly controlled anthracnose and ripening
was delayed by 12 days (Philippine Organic
Agriculture Information Network)
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Management
Anthracnose
Chemical control is effective in the early stages
of infection with one of the following fungicides.
Spray copper oxychloride 0.25
Bordeaux mixture 1
Chlorothalonil 0.2
Carbendazim 0.1.
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Symptoms
Fusarium Wilt
The first internal symptoms develop in feeder
roots, the initial sites of infection.
As the pseudostem is colonized, faint brown
streaks or flecks become evident on and within
older leaf sheaths.
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Symptoms
Fusarium Wilt
Eventually, large portions of the xylem turn a
brick red to brown color.
The first external symptoms of Panama disease are
a yellowing of the oldest leaves.
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Symptoms
Fusarium Wilt
The infected leaves fall in order, from oldest to
youngest, until they hang around the plant like a
skirt of dead leaves.
A younger plant will die soon
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Spread of Disease
Fusarium Wilt
Infected rhizomes are a common means by which
this pathogen is disseminated.
The pathogen can also spread in soil and running
water, and on farm implements and machinery.
Root tips are the natural, initial sites of
infection.
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Management
Fusarium Wilt
No chemical was found to be effective in
controlling this disease.
So it is necessary to take preventive measures to
avoid occurrence of the disease.
Select suckers from fields free from this disease
for planting.
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Management
Fusarium Wilt
Burn the infected plants in the field and destroy
weeds surrounding the area with herbicides.
If possible, restrict the movement of human or
domestic animals in the infected area.
Sterilize the farm tools with disinfectant such
as household bleaching solution (e.g. Clorox)
before using them in another garden.
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Symptoms
Freckle leaf spot
This disease affects both leaves and fruits of
banana.
It is caused by a fungus, which has two names,
Phyllosticta musarum and Guignardia musae. mptoms
This has occurred because the fungus produces two
types of spores.
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Freckle Leaf Spot
Symptoms
The most characteristic symptom of both types of
spot is a sandpaper feel to the leaf and fruit.
This is caused by the fungal structures
protruding through the surface of the leaf.
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Freckle leaf spot
Symptoms
Both the large and small spots are dark brown to
black in color.
The small spots are less than 1mm in diameter and
appear sooty (Fig.).
They can run together to form streaks.
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Freckle leaf spot
Symptoms
The larger spots are up to 4mm in diameter and
can also appear as streaks.
Spots can also appear on the midrib of the leaf
(Fig.) and on the petioles.
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Freckle leaf spot
Symptoms
Reproductive spores are emitted from the leaf in
wet weather and the water moves the spores as it
runs across the leaves.
These spores are also spread by wind.
This leads to the streaking.
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Freckle leaf spot
Management
Mancozeb, DMIs and Benomyl, which are used to
control yellow Sigatoka, will provide effective
control of this disease also.
The use of a plastic bag cover over the bunch may
in the long run be the most economical control
for freckle.
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