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DFID research: The threat to cassava production from pests and diseases

The threat to cassava production from pests and diseases.

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Production of cassava, one of the world’s most important food crops, is precarious and could be toppled by a perfect storm of pests and diseases, according to a new study by scientists at the International Center for Tropical Agriculture (CIAT). The study was funded by HarvestChoice, an initiative of the International Food Policy Research Institute (IFPRI) and the University of Minnesota.

Cassava is the third-most important food crop in the tropics after rice and maize, and is consumed daily by up to one billion people, mostly in sub-Saharan Africa. Prized for its ability to thrive in harsh conditions, cassava produces its carbohydrate-rich roots in poor soils, even in times of drought. Industrial cassava production is also a crucial source of income for hundreds of thousands of smallholder famers.

Threats to cassava production: known and potential geographic distribution of four key biotic constraints, just published in the journal Food Security, identifies hotspots around the cassava-producing world where conditions are right for outbreaks of some of the crop’s most formidable enemies: whitefly, green mite, cassava mosaic disease and cassava brown streak disease.

By using a technique known as ecological niche modeling, CIAT scientists were able to conduct a detailed global risk assessment for cassava, in relation to the four pests and diseases. They compared cassava producing areas where they are already present, with areas that have similar environmental conditions, but where specific pest and disease pressure is either absent or low.

They found that the conditions are right for combined outbreaks of all four pests and diseases in some of the world’s major cassava producing zones. These include Africa’s Rift Valley region, much of Southeast Asia, southern India, Mato Grosso state in Brazil, and northern South America.

The researchers identify movement of infected propagation material as a major cause of the spread of pests and diseases which could enable a pest or disease to jump continents. They highlight the need to refine and enforce the protocols for the movement of propagation material, and also call for more formal international early warning systems for cassava, to ensure a swift response to any outbreaks.

CIAT’s cassava research program is already working to develop cassava varieties resistant to whitefly, green mite and cassava mosaic disease.

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Published 26 August 2011