Originally published on cgiar.org by:International Institute of Tropical Agriculture (IITA) on Sep 1, 2009

Two deadly diseases are threatening to wipe out African bananas and further endangering the food and livelihood security of some 30 million farmers still reeling from the global food crisis. However, in an urgent meeting held last week in Arusha, Tanzania, international experts have come up with a disease management framework aimed at controlling the rapid spread of Xanthomonas wilt and banana bunchy top disease across sub-Saharan Africa.

Disease monitoring studies have indicated that Xanthomonas wilt, which started in Uganda, is spreading to neighbouring countries in eastern Africa, while the banana bunchy top disease is creeping across southern and central Africa.

The workshop, which brought together experts from affected countries and other international scientists and partners, was convened by the International Institute of Tropical Agriculture (IITA), Southern Africa Development Cooperation (SADC),  FAO, and Bioversity International following the rapid spread of the two diseases in the region.

"I am very shocked to discover the extent of the banana bunchy top disease in sub-Saharan Africa and how little attention it has received! It does not reduce yields; it completely eliminates yields destroying propagation materials too," warns Dr Simon Eden-Green, a consultant with the FAO. "We need to be more pro-active in raising awareness on the urgency for policy-makers to act and safeguard the region's food security."

Severe attacks of the banana bunchy top disease, which is characterised by whorly leaves sprouting from the top of the plant and stunting proper growth, were recently reported in central and southern Africa, spurring scientists into action. In a survey, scientists found the disease to have already taken root in 12 countries.

"We found the disease to be well established in Gabon, DRC, Congo Brazzaville, Northern Angola and central Malawi. The farmers are familiar with the symptoms of the disease, likening it to SIDA (AIDS), and calling it 'witches broom'," say Dr Lava Kumar, IITA virologist, who led the survey. The disease is transmitted by an aphid vector that is found in all the banana producing countries in sub-Saharan Africa.

In Malawi, where the disease was first noted in 1994, a survey found 45,000 hectares of bananas in all three regions of the country – north, central and south – are heavily infected. By 2003, the Mkhotakota Cavendish banana was completely wiped out by the bunchy top disease, says Dr Mischeck Soko from the Bvumbewe Agricultural Research Station in Limbe, Malawi.

Results of another survey released earlier this year found the banana Xanthomonas wilt established in Ethiopia, Uganda, Rwanda, western Kenya, North Western Tanzania, North and South Kivu in DRC. Scientists fear the disease is poised to enter Burundi.

Uganda, Africa's leading producer and consumer of bananas, has been battling Xanthomonas wilt since 2001, and had by 2007 saved the equivalent of US$513M worth of crops, a banana expert from Uganda's National Agricultural Research Organisation, Dr Jerome Kubiriba says. The country loses between US$70M and US$200M every year to Xanthomonas wilt. Uganda is on high alert for the banana bunchy top disease from neighbouring countries.

In the DRC, both the bunchy top and Xanthomonas wilt diseases are at play almost crippling banana production. Dr. Patrick Mobambo, the Bioversity country representative, says the bunchy top viral disease has almost wiped out bananas in the Western lowlands bordering Angola, Central African Republic and Congo Brazzaville, while Xanthomonas wilt has caused havoc in the Eastern highlands bordering Uganda.  

"The two diseases have caused losses of up to 90 per cent in some of the areas under attack, increasing the poverty levels of a people recovering from the effects of many years of war," says Dr Mobambo. "In some villages, people have been forced to switch to cassava." 

Currently, all bananas are susceptible to the two diseases, which necessitates more research into the continent's bananas. The diseases require drastic and expensive control measures, such as completely excavating and burning or burying the infected plants, in order to totally destroy the diseases.

Most countries in central, eastern and southern Africa have been struggling on their own without realising their neighbours are also contending with the same disease. Therefore, experts are calling for a regional and integrated approach to control and mitigate the effects of these diseases.

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For more information, please contact:

Dr. Lava Kumar, l.kumar@cgiar.org
Virologist
IITA-Headquarters
Ibadan, Nigeria

Catherine Njuguna, c.njuguna@cgiar.org
Corporate Communications Officer (East Africa)
IITA-Tanzania

Jeffrey T Oliver, o.jeffrey@cgiar.org
Corporate Communications Officer (International)

Communication Office
IITA - Headquarters
Ibadan, Nigeria

URL: www.iita.org

About IITA
Africa has complex problems that plague agriculture and people's lives. We develop agricultural solutions with our partners to tackle hunger and poverty. Our award winning research for development (R4D) is based on focused, authoritative thinking anchored on the development needs of sub-Saharan Africa. We work with partners in Africa and beyond to reduce producer and consumer risks, enhance crop quality and productivity, and generate wealth from agriculture. IITA is an international non-profit R4D organization founded in 1967, governed by a Board of Trustees, and supported primarily by the CGIAR.