UN warns cassava virus, first identified by Bristol researchers, nearing an epidemic in Africa

A virus that attacks the cassava plant – estimated to be the world’s third most important staple crop – is reaching epidemic proportions in parts of Africa, UN scientists warned today.

Cassava brown streak virus (CBSV) was first identified by Professor Gary Foster and colleagues in the Molecular Plant Pathology and Fungal Biology Group in the University of Bristol’s School of Biological Sciences.

The virus causes cassava brown streak disease (CBSD) which can lead to losses of up to 100 per cent – and typically more than 60-70 per cent – of root harvest in susceptible varieties of cassava, as well as reducing the crop’s 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 across 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 an excellent crop 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 CBSV in 2001 by the Bristol Group led by Professor Foster.  His identification of CBSV as the causal agent of CBSD was instrumental in the development of the diagnostic detection systems that are vital in the fight to prevent the spread of the disease and in developing resistant crop varieties.

Bristol’s cassava research was highlighted as a major breakthrough in the UK Government’s 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.