Cassava production under threat
Aug 23, 2011
Production of cassava, one of Uganda’s staple foods, is precarious and could be toppled by a perfect storm of pests and diseases, according to a new study by scientists at the International Centre for Tropical Agriculture (CIAT).
Production of cassava, one of Uganda’s staple foods, is precarious and could be toppled by a perfect storm of pests and diseases, according to a new study by scientists at the International Centre for Tropical Agriculture (CIAT).
Threats to casssava 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.
“It is true we are faced with such threats,†said Prof George Nape, the pioneer fighter against the cassava mosaic that wreaked havoc in the country in late 1980s
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. It is estimated that 200,000 tonnes of cassava flour is consumed in Uganda annually.
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.
Global risk assessment
By using a technique known as ecological niche modeling, CIAT scientists were able to conduct a global risk assessment for cassava, in relation to the four pests and diseases.
They found that the conditions are right for outbreaks of all four pests and diseases in Africa’s Rift Valley region, much of Southeast Asia, southern India, Mato Grosso state in Brazil, and northern South America.
“The research shows that there are perfect niches for some highly damaging pests and diseases in areas currently considered safe havens,†explained CIAT entomologist Dr. Tony Bellotti, one of the article’s authors. “An outbreak of one of these could be very severe, but all four at once would wreak havoc.â€
“Historically, cassava pests and diseases have demonstrated a remarkable ability to colonise new areas in new countries, if conditions are favourable,†he continued.
“We’re already getting reports of sightings of pests in new areas, which seem to support our findings.â€
Raising the stakes
A major cause of the rapid spread of cassava pests and diseases is the method by which the crop is propagated, with new plants grown from stakes - stem cuttings taken from older plants. As well as helping transfer infections from one generation of cassava crops to the next, the stakes are often transported very large distances enabling the spread of pests and diseases far beyond their geographic centres of origin.
“In an age of global travel, local risks to cassava production are now global risks - all it takes is one contaminated stake and a pest or disease could jump an entire continent and establish itself very quickly,†continued Dr. Bellotti.
“If we’re going to protect one of the world’s most important crops, it is going to be critical to refine protocols for the movement of stakes.â€
The authors also recommend the more formal international early warning systems for cassava.
“There’s no doubt that with good preparation, the more effective the response will be. Without a coordinated international effort to monitor the risks and raise the alarm, it is almost inevitable that these potential niches will eventually see real and serious outbreaks.â€
The study, funded by HarvestChoice, an initiative of the University of Minnesota and the International Food Policy Research Institute (IFPRI), also highlights the need for renewed emphasis on research into plant hosts, viruses and disease vectors, as well as their natural enemies, and for these to be combined with integrated pest and disease control strategies at regional, landscape and local levels.
“The models confirmed what we always thought could happen,†said CIAT’s Beatriz Herrera, the report’s lead author.
“Quantifying risk is complicated and ecological niche modeling has its limitations, but these results should allow us to prepare for the worst-case scenarios by developing strategies to help smallholder farmers in the danger zones.â€
CIAT’s cassava research program is already working to develop cassava varieties resistant to whitefly, green mite and cassava mosaic disease.
CIAT
Threats to casssava 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.
“It is true we are faced with such threats,†said Prof George Nape, the pioneer fighter against the cassava mosaic that wreaked havoc in the country in late 1980s
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. It is estimated that 200,000 tonnes of cassava flour is consumed in Uganda annually.
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.
Global risk assessment
By using a technique known as ecological niche modeling, CIAT scientists were able to conduct a global risk assessment for cassava, in relation to the four pests and diseases.
They found that the conditions are right for outbreaks of all four pests and diseases in Africa’s Rift Valley region, much of Southeast Asia, southern India, Mato Grosso state in Brazil, and northern South America.
“The research shows that there are perfect niches for some highly damaging pests and diseases in areas currently considered safe havens,†explained CIAT entomologist Dr. Tony Bellotti, one of the article’s authors. “An outbreak of one of these could be very severe, but all four at once would wreak havoc.â€
“Historically, cassava pests and diseases have demonstrated a remarkable ability to colonise new areas in new countries, if conditions are favourable,†he continued.
“We’re already getting reports of sightings of pests in new areas, which seem to support our findings.â€
Raising the stakes
A major cause of the rapid spread of cassava pests and diseases is the method by which the crop is propagated, with new plants grown from stakes - stem cuttings taken from older plants. As well as helping transfer infections from one generation of cassava crops to the next, the stakes are often transported very large distances enabling the spread of pests and diseases far beyond their geographic centres of origin.
“In an age of global travel, local risks to cassava production are now global risks - all it takes is one contaminated stake and a pest or disease could jump an entire continent and establish itself very quickly,†continued Dr. Bellotti.
“If we’re going to protect one of the world’s most important crops, it is going to be critical to refine protocols for the movement of stakes.â€
The authors also recommend the more formal international early warning systems for cassava.
“There’s no doubt that with good preparation, the more effective the response will be. Without a coordinated international effort to monitor the risks and raise the alarm, it is almost inevitable that these potential niches will eventually see real and serious outbreaks.â€
The study, funded by HarvestChoice, an initiative of the University of Minnesota and the International Food Policy Research Institute (IFPRI), also highlights the need for renewed emphasis on research into plant hosts, viruses and disease vectors, as well as their natural enemies, and for these to be combined with integrated pest and disease control strategies at regional, landscape and local levels.
“The models confirmed what we always thought could happen,†said CIAT’s Beatriz Herrera, the report’s lead author.
“Quantifying risk is complicated and ecological niche modeling has its limitations, but these results should allow us to prepare for the worst-case scenarios by developing strategies to help smallholder farmers in the danger zones.â€
CIAT’s cassava research program is already working to develop cassava varieties resistant to whitefly, green mite and cassava mosaic disease.
CIAT