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Mango Anthracnose: Cause, Symptoms and Management


Mango Anthracnose: Identification, Symptoms and Damage, Management Practices

The Anthracnose of Mango is a very serious fungal disease of mango plant. Identification of the Symptoms and Damages, and the Management Practice  of the disease on the right time is economically very important.

Contents

  • What is anthracnose in mango?
  • Identification: Symptoms and damages.
  • The causal organism.
  • Disease cycle.
  • Management of anthracnose in mango.

Also read: Side grafting in mango

What is mango anthracnose?

The Anthracnose of Mango is a fungal disease cuased which is by the fungus Colletotrichum gloeosporiodes Penz.

It is a widespread fungus disease of mango all over the world. It is particularl in humid areas.

Distribution: India, Sri Lanka, Pakistan, France, Brazil, Indonesia, Trinidad, Mexico, United States of America, Peru, Portugal, Hawaii and the Philippines.

Association: Blossom blight, wither tip.

Results:

1. BER results bin poor fruit set.
2. Early infection causes premature fruit-drops.
3. The blemished ripe fruits.

Also read: Flower and fruit drop in mango and management

Identification: Symptoms and damages

  • Leaf observation.
  • Twig, branches and stalk observation.
  • Inflorescence observation.
  • Flower observation.
  • Fruit observation.

Leaves

Shape of the leaf: It is irregular.
Spots on leaves: The presence of black necrotic spots on the both sides of leaves.

The spots increase in size under humid conditions and advance to form inregul necrotic patches.

Category of leaves: Young are most susceptible to anthracnose.

Twig, branches and stalk

Wither tip of die-back: The die-back appears at the tip of younger branches.

Development of necrotic area: The black necrotic areas are formed on the affected twigs. Affected parts start drying from the tip downwards. Defoliation of the branches is Common.

Also read: Water sprout in mango

Stalk: Elongated dark gray to black lessions appear.

Inflorescence: In Blossom blight, inflorescence stalk and flowers are the most susceptible parts.

Flower: The black necrotic lessions dry and turn to black.

Fruits

Small size fruits: Pea size fruits are susceptible. Fruit senescence is common.

Bigger fruits

Cause of senescence: Self thinning and other physiological causes.
Appearance of fruits: Mummified fruit. Fungus sporulates abundantly on them.

Ripening fruits

Characteristics are:

  • Development of black spots.
  • Various spots.
  • Spots may be sunken.
  • They may show surface crack.
  • These spots, together make bigger spots.
  • Can affect the whole fruit.

Major characteristic

Spots are often concentric at the stem end.
May also concentric streaks towards one side of the fruit.
The downward spread of spores is due to the rain water from the stem end.

Some other characteristics

Spots are restricted to the skin.
Sometimes, infection of pulp is common.

Advance stage

The fungus produces acervuli and abundant orange to salmon pink masses of conidia.

Also read: Veneer grafting in mango

The causal organism and etiology

  • General information.
  • Mycelium.
  • Acervuli.
  • Conidia.
  • Germination of conidia.
  • Infection of immature fruit

General information

The causal organism is a fungus.

Scientific name: Colletotrichum gloeosporiodes Penz.

Also affects: Citrus species, avocado etc.

The fungus is heterothallic.

Mycelium

  • It is haploid.
  • Mycelium consists of narrow and sparsely septate hyphae.
  • Stage of hyphae: Hyaline in early stage and slightly dark in later stage.

Acervuli

Forms on the host surface.
Develops as tangled subepidermal hyphae.

Also read: Cause of mango deterioration

Conidia

  • Conidiophores arise from hyphae.
  • It raises the epidermis.
  • One or more conidia may form from the apex of each conidiophores.
  • Conidia remains in a mucilaginous matrix.
  • This prevent pre-germination.

Germination of conidia

  • Conidia swells and ruptures in the presence of moisture.
  • It is disseminated by rain drops and other animals.
  • The conidial germ tube form dark appressoria.

Infection of immature fruit

  • Penetration is delayed and appressoria enter a period of quiescence.

Disease cycle

  • Source of primary infection.
  • Spread of pathogen.
  • Ideal temperature for the production of conidia (acervuli)
  • The ideal temperature for the production of conidia (fruit)
  • How does conidia enter in fruits?
  • Germination of quiescence.
  • Important points.

Also read: Best Time for grafting in mango

Source of primary infection

Diseased twigs, leaves, fruits, etc., are the major sources of primary infection.

The fungus has a long saprophytic survival ability on dead twigs.

Spread of pathogen

Pathogen spreads within tree canopies as water borne conidia. This is common during the rain.

Long rain days helps in severe outbreak of the disease.

Ideal temperature for the production of conidia (acervuli)

Temp.: 10 – 30°C.
Relative humidity: 95 – 97%.

Ideal temperature for the production of conidia (fruit)

Temp.: 25°C.
Relative humidity: 95 – 100%.
More infection: Form blossoming to half size fruit.

How does conidia enter in fruits?

  • It enters through the pores of green fruits.
  • The dormant stage may enter if there is antifungal compound present in fruits.

Termination of quiescence: When the fruits start ripening and there is a reduction in antifungal compound.

Important points

  • The pathogenicity genes are not expressed at pH level 4.
  • Ethylene production may terminate quiescence.
  • The fungus excretes and accumulates ammonia.

Dispersal of conidia by rain is the most common way.

Also read: Phytoplasma diseases of plants

Management of anthracnose in mango.

  • Irrigation
  • Feritilization
  • Sanitation
  • Pruning
  • Use of copper fungicide after pruning
  • Zineb
  • Use of systemic fungicide
  • Post harvest treatment
  • Biological control

Irrigation: Proper irrigation during the summer season is very necessary to maintain the tree vigor.

Feritilization: Proper feritilization throughout the year is also a very necessary process to maintain the tree vigor.

Sanitation: It is a very important step which keeps the pathogen away from the mango trees.

Pruning: Diseased parts are pruned and treated by using copper fungicide.

Zineb: At the time of flowering. Subsequent spraying is done just before the onset of monsoon and it continues till harvest at 14 days interval.

Use of systemic fungicide

Benomyl and thiobendazole
250 mg/l.

Also read: Epicotyl grafting in mango

Post harvest treatment

Post harvest chemical: Instantaneous dip of fruits in 1000 ppm benomyl or 2000 ppm of thiobendazole before storage.

Hot water treatment: The hot water treatment of langra and dasehari using hot water + 0.1% carbendazim gives 100% result.

Vapour heat treatment: 47°C for 15 minutes.

Hot water brushing: 15 – 20 second hot water spray and fruit bruising. It enhance the shelf life of mango fruits.

Biological control

Strains of Bacillus cereus and Pseudomonas fluorescence are effective.

The yeast Rhodotorula minuta is a strong antagonist.

Treatment of mango fruits using benzothiadiazole is effective.

Anthracnose


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