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Mango malformation disease

Have you seen mango malformation disease?

Mango malformation disease is prohibited matter under the Biosecurity Act 2014. Be on the lookout for these symptoms and report them to Biosecurity Queensland on 13 25 23.

Early detection and reporting of symptoms are the key elements in controlling the pest.

Do not move any plant material off your property-this can spread the disease.

  • MMD distorted leaf bud
    MMD distorted leaf bud
  • Normal leaf bud
    Normal leaf bud
  • MMD distorted flower panicle
    MMD distorted flower panicle
  • Normal flower panicle
    Normal flower panicle

General information

Mango Malformation Disease (MMD) is a fungal disease of mango plants, particularly mango flowers.  

The disease occurs in many mango production areas around the world.

Of the Fusarium species associated with MMD internationally, F. mangiferae is the most well-known and understood cause of the disease.

Fusarium mangiferae was first detected in Australia in 2007. It has been successfully eradicated from Queensland.

Be on the lookout for symptoms and immediately report them to Biosecurity Queensland. Do not move any plant material off your property as this can spread the disease.

Call Biosecurity Queensland on 13 25 23 or the Exotic Plant Pest Hotline on 1800 084 881.

Overview

What causes MMD?

Fusarium mangiferae.

Other namesMango Malformation Disease
Description 

The disease can cause abnormal flower, leaf and shoot growth. Young nursery plants can be severely stunted.

MMD results in reduced plant growth and fruit yield.

Distribution

MMD occurs throughout many mango production areas around the world.

The disease is known to occur in the Northern Territory.

Lifecycle
  • MMD can affect mango trees of all ages, though nursery plants are most susceptible.
  • Fungal spores are formed on dying infected plant parts such as malformed flower panicles.
  • The mechanism for disease transmission within a tree or between trees is poorly understood.
  • Infection most likely occurs in emerging buds of flowers and shoots.
  • Wounding may assist the spores’ establishment in the host and disease development.
  • Mango bud mites, Aceria mangiferae, have been implicated in localised spore spread on mango plants.
  • The disease spreads slowly within affected orchards.
  • The disease can remain dormant for several years before showing symptoms or initiating an epidemic.
  • The disease is not transmitted within fruit or seeds.
Crop(s) affected 

MMD is only known to affect mango plants (Mangifera indica L.).

Host(s) Mango (Mangifera indica).
Symptoms

Common signs are abnormal, compact development of shoots and flowers. Both normal growth and growth affected by MMD may be present on the same plant.

Shoots

Growing points such as leaf and stem buds produce misshapen shoots with short internodes and brittle leaves. The leaves are much smaller than those of healthy plants and re-curve towards the stem giving a squat, bunchy-top appearance.

Shoot damage can occur in mature trees, though young plants can be severely stunted.

Flowers

Affected flower stems or panicles are thickened and highly branched, producing up to 3 times the normal number of flowers.

Flowers are enlarged, sterile and do not bear fruit. There are often high numbers of male flowers compared with perfect flowers. Panicles may also form dwarfed and distorted leaves instead of flowers.

Impacts

Mango malformation disease does not kill the tree, but can severely reduce its yield.

Internationally, MMD is regarded as one of the most economically important diseases of mango.  Estimated crop losses have been reported to be as high as 80 to 100% in some regions of the world.

The lack of severe symptoms seen in Australia to date could indicate the presence of a different strain of F. mangiferae to the strains causing losses overseas, though further research is required to confirm this.

There are no impacts on human health from MMD and mango fruit is safe to eat.

Spread

Long distance spread is by movement of infected plant material. The disease spreads slowly within affected orchards.

MMD can be spread by grafting with infected budwood and by movement of infected nursery plants.

In an affected orchard, fruit can be contaminated with viable spores, though these can be treated with post-harvest washing or fungicide application.

Monitoring and action

Inspect mango trees during the flowering season for floral symptoms of the disease. Monitoring for malformed leaves and shoots can occur throughout the year.

If you see symptoms of MMD, contact Biosecurity Queensland on 13 25 23, and they will advise how to take action. Do not move any plant material off your property as this can spread the disease.

Control

There is no cure for MMD once the disease is established.

There are simple steps you can take to protect your farm:

  • Make sure that you and your farm workers are familiar with the symptoms of MMD and what to look for.
  • Regularly check your orchard and report any unusual or unfamiliar symptoms.
  • To avoid introducing MMD onto your property:
    • establish new plantings with reputable pest and disease-free nursery stock.
    • check on arrival that any new plants are free from pest and diseases.
    • if detected, isolate affected plants from healthy plants until official checks are completed.
  • Ensure that workers, visitors, vehicles and equipment are decontaminated before they enter and leave your farm

Effective hygiene management of pruning equipment can prevent disease spread on farm.

Quarantine restrictions

Mango malformation disease is prohibited matter under the Biosecurity Act 2014. This means that by law, it must be reported to Biosecurity Queensland on 13 25 23 without delay.

Movement restrictions are in place under the Biosecurity Regulation 2016. A biosecurity certificate is required to move a mango plant (excluding destemmed fruit) into Queensland unless sourced from a state or part of a state that is certified free from mango malformation disease.

Further information

Last updated 28 February 2018