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Fungal Diseases

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Banana

Fungal Diseases of Banana

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Black Sigatoka, also known as black leaf streak, was named for its similarities with the Yellow Sigatoka

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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.


Symptoms

Initially, tiny brown streaks appear on the underside of the third and fourth leaves.

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After the streak stage, spots develop. These spots increase in size and gradually turn brown in color.

Sigatoka leaf spots


Symptoms

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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Sigatoka leaf spots


Symptoms

Destruction of mature and functional leaves in large number leads to failure of bunches to fill out and ripen.

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Fruit set will be poor with reduced size, uneven ripening and angular shape having discolored flesh.

Sigatoka leaf spots


Spread of disease

The fungus produces conidia and ascospores, both of which are infective.

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Infected planting material and leaves, which are used often as packing materials, are usually responsible for the long-distance spread of the disease.

They are formed under high moisture conditions, and are disseminated by wind, and in the case of conidia, also by rain and irrigation water.

Sigatoka leaf spots


Spread of disease

Humid weather and high rainfall periods hasten the development and faster spread of the disease.

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Soils with poor drainage and low fertility are more conducive for disease build up.

Under a crowded canopy and humid condition, the conidia rapidly spread the disease on to a susceptible variety.

Sigatoka leaf spots


Management

The suckers brought for planting should be disease free. They should be dipped in a fungicide solution before planting.

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Severely infected plants and leaf blades should be removed and destroyed.

Proper, wider spacing must be practiced. The orchard must be clean and free from weeds and grasses to avoid humidity build up.

Sigatoka leaf spots


Management

Periodical roguing of diseased leaves reduces the spread of the disease.

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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.

The land should be well drained and leveled to avoid any water stagnation.

Sigatoka leaf spots


Management

One of the following fungicides also can be sprayed.

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Benomyl 1 g/l or Mancozeb 2 g/l

Carbendazim 1 g/l

Copper oxychloride 2.5 g/l

Ziram 2 ml/l

Chlorothalonil 2 g/l

Sigatoka leaf spots


Anthracnose

It is an important post-harvest problem of bananas especially during transport and storage.

Pulp of diseased fruit is usually not affected unless the fruit is over-ripe.

Infection in young fruit is not always manifested until the fruit ripens,

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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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Anthracnose Symptoms


Anthracnose spreads to banana plants by wind, insects, water and birds.

The fungus thrives in heavy rainfall and temperate weather conditions.

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Spread of diseaseAnthracnose

The fungus that causes anthracnose also causes crown rot, another rot-disease of banana.


Practice good field sanitation.

Minimize bruising during fruit handling.

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ManagementAnthracnose

Treat the fruit with hot water for 5 min at 50°C.

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)


Chemical control is effective in the early stages of infection with one of the following fungicides.

Spray copper oxychloride 0.25%

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ManagementAnthracnose

Bordeaux mixture 1%

Chlorothalonil 0.2%

Carbendazim 0.1%.

Back


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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SymptomsFusarium Wilt

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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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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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Infected rhizomes are a common means by which this pathogen is disseminated.

Spread of DiseaseFusarium Wilt

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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.


No chemical was found to be effective in controlling this disease.

ManagementFusarium Wilt

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So it is necessary to take preventive measures to avoid occurrence of the disease.

Select suckers from fields free from this disease for planting.


Burn the infected plants in the field and destroy weeds surrounding the area with herbicides.

ManagementFusarium Wilt

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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.


This disease affects both leaves and fruits of banana.

SymptomsFreckle leaf spot

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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.


The most characteristic symptom of both types of spot is a sandpaper feel to the leaf and fruit.

Freckle Leaf Spot

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This is caused by the fungal structures protruding through the surface of the leaf.

Symptoms


Both the large and small spots are dark brown to black in color.

Freckle leaf spot

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The small spots are less than 1mm in diameter and appear sooty (Fig.).

They can run together to form streaks.

Symptoms


The larger spots are up to 4mm in diameter and can also appear as streaks.

Freckle leaf spot

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Spots can also appear on the midrib of the leaf (Fig.) and on the petioles.

Symptoms


Reproductive spores are emitted from the leaf in wet weather and the water moves the spores as it runs across the leaves.

Freckle leaf spot

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These spores are also spread by wind.

Symptoms

This leads to the streaking.


Mancozeb, DMIs and Benomyl, which are used to control yellow Sigatoka, will provide effective control of this disease also.

Freckle leaf spot

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The use of a plastic bag cover over the bunch may in the long run be the most economical control for freckle.

Management

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Next Fungal Diseases of Banana. Fungal Diseases of Banana Click on the disease End Sigatoka leaf spots Anthracnose Fusarium wilt Freckle leaf spot