Originally published on cgiar.org by:International Institute of Tropical Agriculture (IITA) on Mar 24, 2010

Two deadly banana diseases stalking banana and plantains in eastern and central Africa, if left uncontrolled, could spell doom for over 70 million farmers who depend on the crop for their food and livelihoods.
 
The alarming rapid spread of the bacterial Banana Xanthomonas Wilt (BXW) and the viral Banana Bunchy Top Disease (BBTD) are poised to wreak havoc to Africa’s production as all current banana and plantain varieties in the continent are susceptible.

The silent spread

Of major concern is BBTD, described as banana’s version of AIDS by Lava Kumar, plant virologist with the International Institute of Tropical Agriculture (IITA). The disease is characterized by stunted plants with leaves curling at the top. Infected plants do not produce fruits and eventually die.

BBTD is caused by the banana bunchy top virus (BBTV), classified as among the World’s 100 Worst Invasive Alien Species by the Invasive Species Specialist Group (ISSG) of the World Conservation Union (IUCN).  BBTV is spread by the banana aphid, Pentalonia nigronervosa, which is found in almost all the banana and plantain growing countries. However, the main culprit of the rapid spread of the virus is the movement of diseased planting material as farmers unknowingly share infected suckers.

The disease is very difficult to identify in newly infected plants and is often missed by growers and extension specialists. A BBTD assessment study conducted by IITA in 2008 confirmed this, adding that there was generally poor awareness about this disease among farmers and government agencies. All these have contributed to the disease’s unabated spread in the region.

According to Dr Kumar, though BBTD was first recorded in Egypt about 100 years ago, it had limited distribution and only began to rapidly spread into new production areas in the last two decades.

The disease has already caused massive damage in Malawi, DR Congo, Gabon, Burundi, and Rwanda. It has also entered Angola, Mozambique, Zambia, and Cameroon.

In DR Congo, BBTD has been noted in the Kivu provinces just opposite Uganda – the largest banana-producing country in Africa and home to the East African Highland bananas.

This is alarming because soon it will start to spread to eastern Africa where bananas and plantains are already suffering from BXW. This “double whammy” could spell a fatal economic blow to resource-poor farmers in the region that they might not be able to recover from.

A united front to combat threats

IITA and partners are working overtime to bring the diseases under control. In 2009, FAO, IITA, Bioversity International, and the Southern Africa Development Cooperation teamed up to organize an international workshop on BBTD held in Arusha, Tanzania. Participants of the confab issued a ‘joint statement’, which is to become the prelude to the development of a regional banana disease management framework.
 
IITA have also recently launched a regional disease survey involving seven countries: DR Congo, Kenya, Rwanda, Tanzania, Uganda, and Zambia in coordination with local partners. The survey, funded by the FAO, covered the major banana diseases but especially focusing on BBTD.
 
Fen Beed, IITA plant pathologist, said the seven countries were selected because either BBTD had been reported there or they are at high risk of contracting the disease from neighboring countries. For instance, southwest Uganda is in danger of getting BBTD as the disease is present in northern Rwanda and eastern DR Congo.

"Where a disease is not yet present but is likely to be introduced, an effective surveillance system increases awareness of the disease symptoms among those concerned. This ups the chances of farmers and their representatives to correctly detect and report a disease when it does arrive," he explained. "This allows the destruction of infected plants to prevent disease establishment and spread."

The survey will involve recognition of symptoms in the field and confirmation of the disease in the laboratory using biotechnology tools. It will also make use of Geographical Positioning System (GPS) to generate GIS maps showing the presence and spread of the diseases.

Aside from carrying out disease surveys and capacity-building activities, IITA has also been working alongside partners to sensitize donors, government and inter-governmental agencies, and farmers on BBTD. They have various public awareness materials including videos and flyers in the local language with tips on managing the disease, emphasizing on planting healthy material and destroying infected mats.

IITA has also partnered with the University of Hawaii to develop a biocontrol for insect vectors of the disease. Rachid Hanna, IITA entomologist who is leading this endeavour, said efforts are underway to identify natural enemies of the banana aphid and determine their effectiveness in controlling the pests’ population.

If successful, he said, biological control would provide a cost-effective and sustainable alternative to chemical pesticides in minimizing the spread of the disease or even reducing it to very low levels.

Breeding-for-resistance studies are also being explored to provide another line of line of defense against the deadly diseases.

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For more information, please contact:

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

Dr. Fen Beed, f.beed@cgiar.org
Plant Pathologist
IITA-Tanzania

Dr. Rachid Hanna, r.hanna@cgiar.org
Biocontrol Specialist
IITA-Cameroon

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

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