Cassava virus epidemic in Africa

18 Nov 2011

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UN warns that cassava virus, first identified by Bristol Group, is nearing an epidemic in parts of Africa

As reported in recent BBC News item UN scientists are warning that a virus attacking the cassava plant is nearing an epidemic in parts of Africa.

The virus causes a disease called cassava brown streak disease (CBSD) causes losses up to 100% and typically >60-70% of root harvest in susceptible varieties of cassava, as well as greater increases through reducing the market value due to necrotic lesions. CBSD has become an extremely serious constraint to cassava production in East Africa as well as a threat to cassava production throughout Africa.  CBSD is listed as one of the seven most dangerous plant diseases in the world for the impact it can have on food and economic security throughout Africa.

Cassava has been estimated to be the world’s third most important staple crop, providing carbohydrates for around 200 million people in Africa.  Cassava is a crop excellent for poor farmers as it can be cultivated year round and has flexibility in its harvesting times, providing food in periods when other food staples are not available.  Its ability to better withstand drought and grow in poorer soils than other staples, is also contributing to cassava replacing maize as a primary food crop.

From when CBSD was first reported in 1936 in East Africa, it took 65 years before the causal agent was identified as Cassava brown streak virus (CBSV)by the Bristol Group in the School of Biological Sciences lead by Professor Gary Foster in 2001. His identification of Cassava brown streak virus as the causal agent of CBSD was instrumental in development of the diagnostic detection systems, vital in the fight to prevent spread and in developing resistant varieties. Both papers were published in the BSPP journal Plant Pathology.  The cassava research was highlighted as a major breakthrough in the UK Governments Report on ‘Achievements of Research Department for International Development 1996-2000’. The group has hosted visiting fellows from Uganda working on variation of CBSV in the field and continues to research into this serious disease, recently forming and leading an international consortium to coordinate research efforts.

cassava
CBSD leaf symptoms  / CBSD tuber symptoms

Monger, W.A., Seal, S., Cotton, S. and Foster, G.D. (2001) Identification of different isolates of Cassava brown streak virus and development of a diagnostic test.  Plant Pathology 50, 768-775
Monger, W., Seal, S., Issacs, A. and Foster, G.D. (2001) The molecular characterisation of the cassava brown streak virus coat protein.  Plant Pathology 50, 527-534