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Posts Tagged ‘International Institute of Tropical Agriculture’

Kenya: Maize remains the food of choice for many people

Posted by African Press International on September 4, 2013

KISUMU,  – A maize research facility designed to reduce the time it takes to research and develop varieties resistant to viral maize lethal necrosis (MLN ), which has been reported in East Africa since 2011, is to be established in Naivasha, Kenya.
The facility, funded to the tune of US$1.2 million by the Bill and Melinda Gates Foundation, is expected to be operational by the end of September 2013.

“The facility will enable public and private sector institutions that are engaged in the development and delivery of improved maize varieties in Eastern Africa to screen their breeding materials [including inbred lines and hybrids] under reliable disease screening procedures,” Boddupalli Prasanna, an MLN researcher with the International Maize and Wheat Improvement Center (CIMMYT), told IRIN.

“This will help in identification of MLN-resistant maize lines that can be used by these organizations to develop MLN-resistant elite maize varieties that can replace the existing susceptible varieties in the market,” he added.

The facility is expected to serve as a hub for training young researchers and students in Africa on MLN screening and for identifying MLN-resistant maize germplasm. Maize virologists from CIMMYT, the Kenya Agricultural Research Institute (KARI), the International Institute of Tropical Agriculture (IITA) and institutions in the USA (e.g., Ohio State University/US Department of Agriculture) will work together at the facility.

“When you talk to farmers, they tell you it is not profitable to grow maize any more and this can lead to serious shortages of the crop and in turn, food insecurity. Remember that maize remains the food of choice for many people in the region”

MLN first appeared in Kenya’s Rift Valley in 2011 and quickly spread to other parts of Kenya, as well as to Uganda and Tanzania, according to CIMMYT.

MLN occurs after combined infections by two viruses – maize chlorotic mottle virus (MCMV) and either maize dwarf mosaic virus (MDMV) or wheat streak mosaic virus (WSMV). Infected maize plants are short; their leaves show chlorosis (indicating insufficient chlorophyll and thus pale in colour) and they die at about flowering time.

MLN can cause total crop loss if not controlled effectively. Infected plants are frequently barren; ears formed may be small or deformed and set little or no seed.

In 2012, the disease affected an estimated 300,000 smallholder farmers in Rift Valley , traditionally Kenya’s largest maize producing region. This year alone, the government estimates the disease has affected some 18,500 hectares.

Recent research carried out in Kenya by CYMMIT and KARI featuring 119 commercial maize varieties artificially exposed to the virus during 2012-2013, revealed that as many as 117 were susceptible to MLN.

Farmers could switch to other crops

Experts like James Samo, an agricultural production officer at Kenya’s Ministry of Agriculture, say unless the disease is controlled, it could lead to a shortage of maize, as farmers might decide to turn to other crop varieties.

“When you talk to farmers, they tell you it is not profitable to grow maize any more and this can lead to serious shortages of the crop and in turn, food insecurity. Remember that maize remains the food of choice for many people in the region,” he said.

Some farmers told IRIN they plan to plant alternative crops should efforts to control the disease fail.

“Last year alone, I lost crops to the disease worth $1, 200. Come this year, I thought the government would come up with lasting solutions but that never was. Even this year my crops have been attacked yet again. I have since uprooted maize and will then plant millet come next planting season,” Daniel Tirop, a 46-year-old farmer, told IRIN.

In Tanzania, cases of the disease were first reported in August 2012 in Mwanza, near Lake Victoria, and in Arusha.

Rapid spread hampers control efforts

Experts have welcomed efforts to control the disease, saying it has devastated crops – in part due to the lack of knowledge among farmers and agricultural extension officers in identifying it in good time, and also due to its rapid spread.

“Because it is a new disease both to farmers and to agriculture extension officers who are supposed to advise farmers, the disease has become very hard to control. The only option so far and which must be pursued vigorously, is to come up with maize varieties which are resistant to the disease,” Samo told IRIN.
Kenya’s government has spent some $113,000 since 2011 raising awareness of MLN among agricultural extension officers and farmers.

According to CIMMYT, the disease is hard to control because “it is caused by a combination of two viruses that are difficult to differentiate individually based on visual symptoms and also, the insects that transmit the disease-causing viruses may be carried by wind over long distances.”

In the meantime, experts say farmers should rotate crops and diversify as a way of controlling the disease.

“Some interventions include adoption of crop diversification and rotation with non-cereal crops to beat its spread. Since the vectors are insects, so controlling them using chemicals that would stay in the soil for three weeks – long enough to allow the seeds to germinate – combined with development of genetically resistant varieties, could curb the disease,” Mathews Dida, a maize virologist at Kenya’s Maseno University, told IRIN.

Experts say other than developing MNL-resistant varieties, there is a need for “on-farm demonstrations of the improved products, which help farmers to realize the benefits of these new varieties, including their resilience to MLN, and a strong communications strategy [including local media] should be designed and implemented for accelerating the technology’s adoption.”

ho/ko/cb  source


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Food security: Cassava flour is consumed by millions in Africa

Posted by African Press International on May 9, 2013

“Super-fly” threatens “Rambo” cassava, food security

Cassava flour is consumed by millions in Africa

JOHANNESBURG,  – A tiny, rapidly breeding cyanide-munching insect, dubbed a “super-fly” by scientists, is threatening the food security of millions of Africans.

The Bemisia tabaci – one of several whitefly species – carries lethal viruses that cause cassava brown streak disease (CBSD) and cassava mosaic disease (CMD), which have decimated the hardy cassava plant.

Cassava, a tropical root crop, is the third most important source of calories in the tropics, after rice and maize. According to the UN’s Food and Agriculture Organization (FAO), it is the staple food for nearly a billion people in 105 countries, where it comprises as much as a third of daily calories consumed. The cheapest known source of starch, cassava is grown by poor farmers – many of them women – often on marginal land; for these people, the crop is vital for both food security and income generation.

The threat to cassava is particularly alarming as the plant is often called the “Rambo” root for its ability to withstand high temperatures and drought. With climate change expected to take a major toll on maize in the coming decades, many hope cassava will offer an alternative route to food security in Africa. Cassava may also prove to be an important source of biofuel.

Experts plan to take aim at the whitefly this week, at a conference of the Global Cassava Partnership for the 21st Century (GCP21), at the Rockefeller Foundation Bellagio Center in Italy. The conference is dedicated to “declaring war on cassava viruses in Africa.”


From the 1980s to the mid-2000s, CMD ravaged more than 4 million square km in Africa’s cassava-growing heartland, stretching from Kenya and Tanzania in the East to Cameroon and the Central African Republic in the West. But in recent years, the scientific community developed cassava varieties resistant to CMD.

James Legg, a leading cassava expert at the International Institute of Tropical Agriculture (IITA), who works out of Tanzania, told IRIN, “The premature celebrations for this apparent victory were very soon squashed, however, as sinister new reports were received of the occurrence and apparent spread of CBSD in southern Uganda.”

Bemisia tabaci on a cassava leaf

Until then, scientists had assumed that the viruses causing CBSD could not spread at medium-to-high altitudes; the disease had previously only been reported in coastal areas of East Africa and the low-altitude areas around Lake Malawi. “The spread recorded from Uganda instantly cast doubt of the validity of that earlier theory,” said Legg. “Worse still, the disease spread out from Uganda over following years, and into the neighbouring countries of Kenya, Tanzania, Burundi and Rwanda.”

CBSD is now a pandemic, threatening Nigeria, the world’s largest producer and consumer of cassava. The cassava starch industry in Nigeria generates US$5 billion per year and employs millions of smallholder farmers and numerous small-scale processors.

Only in 2005 were scientists able to confirm that the whitefly responsible for spreading CMD was also responsible for spreading CBSD.

“With this realization, it became clear that the spread of these two disease pandemics was really only a consequence of the fact that East and Central Africa was experiencing a devastating outbreak of the whitefly that transmits both of them,” explained Legg.

He told IRIN that in the 1980s, researchers recorded an average of less than one fly per plant, but by the mid-1990s, the number of whiteflies had increased a hundredfold.

“These insects also seem to have a close relationship with the viruses that they transmit, and some evidence has shown that the insects do better on virus-diseased plants”

Arms race

It seems Bemisia tabaci has been assisted by climate change: The warmer temperatures occurring in higher altitudes have created optimal conditions for the insect to breed rapidly, speeding its adaptation and evolution. More importantly, said Legg, is the fact that these flies seem to have worked out how to do better on cassava plants, whose cyanide production deters all but a very small group of insects. As the whitefly population has exploded, rapid spread of the viral diseases – CMD and CBSD – was an inevitable consequence.

What makes a bad situation even worse, however, is that these diseases, in turn, may promote the whitefly. “These insects also seem to have a close relationship with the viruses that they transmit, and some evidence has shown that the insects do better on virus-diseased plants, leading to an ‘I scratch your back, you scratch my back’ type of mutually beneficial relationship,” Legg said.

Scientists are working towards solutions. A member of Legg’s team is examining the impact of climate change on the whitefly in search of ways to deal with the pest. Other planned projects are working to control whiteflies directly, either through introducing other beneficial insects that kill whiteflies, or through producing varieties that combine whitefly and disease resistance.

Efforts to breed high-yielding, disease-resistant plants suitable for Africa’s various growing regions will involve going to South America, where cassava originated, and working with scientists at the cassava gene bank of the International Center for Tropical Agriculture (CIAT), IITA’s sister organization, in Colombia. CIAT is the biggest repository of cassava cultivars in the world.

Experts at the conference in Italy will also discuss a more ambitious plan to eradicate cassava viruses altogether. The aim will be to develop a regional strategy that gradually replaces farmers’ infested cassava plants with virus-free planting material of the best and most disease-resistant cultivars. Approaches to developing these cultivars will include new molecular breeding and genetic engineering technologies to speed up selection. The hope of the team is that by joining forces, and employing the whole range of technologies available, a lasting impact will be made in tackling a crop crisis that poses the single greatest challenge to the future of Africa’s cassava crop.

jk /rz source

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