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Cassava mosaic disease

Preferred Scientific Name: Cassava mosaic disease

Cassava mosaic disease is caused by a combination of the three cassava mosaic geminiviruses. It primarily infects cassava plants and is transmitted by whitefly and the first reported infection was in 1984. Infections result in great economic loss and famine. The virus is the most detrimental disease affecting food supply in Africa.

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Why is it a problem?

Cassava mosaic disease is arguably the most severe disease of any African food crop. While it is hard to estimate total losses, yield losses have been reported to be between 20 - 95% in different countries (Threst et al, 1994). In Africa alone it has been indicated that 12 - 13 million tonnes of yield have been lost to Cassava mosaic disease, worth an estimated US$1.9  - $2.7billion.

As cassava is a popular source of carbohydrate, these rates of crop losses have been a huge cause for concern. It's a highly nutritious crop and can be produced at a high rate, and has recently started to be cultivated on a large, commercial scale. Now, because the scale at which cassava is grown and the devastating impact of Cassava mosaic disease, it is deemed one of the most damaging crop viruses in the world.

Impacts

  • Reduces native biodiversity
  • Negatively impacts livelihoods
  • Implications for a commercial crop

What’s the solution?

Phytosanitation

One way of preventing the spread of Cassava mosaic disease is phytosanitation. This is the process of removing any diseased cassava from the surrounding area where new plants will grow, ensuring that there aren’t any infected stem cuttings in the planting materials. Then monitoring the plant as it grows and removing any parts that become infected.

However, this method faces limitations as the plants are still vulnerable to Cassava mosaic disease contamination.

Resistant crops

Through resistance breeding of cassava, researchers have developed a form of the plant that is less likely to become infected by Cassava mosaic disease. Researchers then breed the cassava with a plant that is resistant to Cassava mosaic disease but does not infringe on the positive elements of the plant, thus creating a hybrid. This hybrid is less likely to be affected by the disease.

Fact file

Name Cassava mosaic disease

Distribution

Asia, Africa

For more information on distribution, view the full datasheet available here

Habitat

Agricultural and cultivated areas 

Natural enemies

N/A

Invasiveness

Now found in all cassava growing regions across Asia and Africa

Likelihood of entry

Spread by Whitefly, dependent on vector

Climate

Tropical

Disease type

Virus

Further reading

Visit our online resource of research and full text articles and journals
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