Almost all of the cassava plants in this field in Kratie, Cambodia, showed symptoms of cassava mosaic or cassava witches’ broom disease. Taken in February 2018. Photo by Madelline Romero/CIAT

CMD threatens 55 million annual cassava production

The Global Cassava Partnerships for the 21st Century (GCP21) has called for urgent regional approach to halt the spread of cassava mosaic disease (CMD) that is threatening cassava production in Southeast Asia—a region that accounts for about 55 million tons of cassava and hosts billions of dollars in cassava investment.

Extensive field surveys and stakeholder interaction in the region conducted by the International Center for Tropical Agriculture (CIAT) and national partners show that CMD is officially present in six provinces of Cambodia and two provinces of southern Vietnam.

In a communique issued today, Dr Claude Fauquet, immediate past Director for the GCP21, said that the proposal for a regional approach followed a special session held during the 4th International Cassava Conference held in Benin from June 11th to 15th 2018.

The objective of the special session was to make the international cassava community aware of the problem and to develop practical suggestions for a rapid action plan with all regional stakeholders to control the epidemic of CMD in this part of the world.

Southeast Asia produces 55 million tons of cassava per year. The current spread of the disease in the region is estimated to be less than 10 percent of the total planted area. Experts agreed that, based on current knowledge about the outbreak, the region is at an early stage of the epidemic and it is still possible to contain the impacts of the disease.

The international cassava community present at the conference expressed strong willingness to collaborate with any regional plan to manage the spread of CMD. In particular, researchers from the African continent can offer extensive accumulated knowledge on CMD, its spread and its control, including diagnostic tools and high yielding CMD-resistant cultivars.

“There is a lot to learn from Africa, a region that managed to contain the spread of the disease in the past,” says Dr Alfred Dixon, Director for Development & Delivery at the International Institute of Tropical Agriculture (IITA).

In Southeast Asia, CMD spreads through infected cassava planting materials. The natural whitefly vectors of the virus causing the disease are present on cassava in the region, and play a role in spreading the virus within fields. They may also play a role in longer distance spread, although this remains to be proven.

Most importantly, the experts pointed out that the transportation and export of starch, chips, flour or fresh roots does not pose a threat of importing the disease through any of these products, allaying concerns on domestic and export trade.

Countries in Southeast Asia are urged to proactively communicate the status of the disease and bond together to mount a coordinated action against the new virus threat to cassava in the region.

Experience with CMD in Africa and Asia has shown that the biggest source of risk for long distance spread from one region to another is the exchange of cassava cuttings. Infected cuttings can be transported hundreds of kilometers in a single day. The whitefly vectors can also spread the disease to up to 100 kilometers per year. Stringent domestic quarantine measures are needed to restrict movement of cuttings from infected districts to other districts. Attention should be made to identify disease-free areas to keep them free of the disease. The commercialization of the cassava industry in Southeast Asia offers opportunities for improving the flow of information to prevent movement of infected planting materials.

 

A regional plan of action could contain the following steps:

 

Short term action

  • Integrate ongoing surveillance data collected by different research groups working in the region to identify currently affected and   immediately threatened areas.
  • Map variety distribution in areas of high CMD incidence using molecular markers.
  • Disseminate information to extension services and farmers to improve recognition and management of the disease.
  • Do rapid multiplication of and distribute virus-free cuttings among farmers in affected parts of the region.

Mid-term action

  • Import, test, and multiply existing CMD-resistant material in several locations in the region.
  • Develop by introgression the source of CMD resistance present in African varieties into improved materials in Southeast Asia.

Long-term action

  • Introgression of virus-resistant genes into varieties that meet regional needs

The GCP21 is rallying stakeholders in Southeast Asia to come together to address the challenge posed by CMD. A regional meeting will soon be held with a view to developing a detailed plan of action and collaboration on interventions needed, in order to prevent the disease from negatively impacting the vibrant cassava industry in the region.

 

This article is a reworded version of the press release distributed by GCP21.

Founded in 2003, Global Cassava Partnerships for the 21st Century is a not-for-profit international alliance of 45 organizations and coordinated by Claude Fauquet and Joe Tohme of the International Center for Tropical Agriculture (CIAT). It aims to fill gaps in cassava research and development to unlock the potential of cassava for food security and wealth creation for poor farmers.

For press interviews, please contact: Claude Fauquet, Director of GCP21, c.fauquet@cgiar.org, or, Godwin Atser, Conference Communication Coordinator, g.atser@cgiar.org.

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