Cassava Stories
CMD Outbreak in Mainland SEA

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Title: CMD Outbreak in Mainland SEA
Authors: Claude Fauquet*
Date: September 2018
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Summary: In 2016, the first report of cassava mosaic disease – CMD, was published, reporting the unequivocal identification of the Sri Lankan cassava mosaic virus as responsible for CMD symptoms in the north east of Cambodia as early as 2015. Since that date, several surveys have been done in Cambodia, Vietnam and Thailand, and as of mid 2018, the disease was present in 6 provinces in Cambodia and ten provinces in Vietnam. There is still not a single case reported in Thailand. In 3 years, the disease progressed from a single plantation in Rattanakiri Province in Cambodia to an estimated 8% of the surfaces cultivated in the whole region. Therefore, the impact is still quite limited but growing quickly. The disease is transmitted in two ways: by the natural whitefly vector (Bemisia tabaci, Aleyrodidae) and by the cassava cuttings. There is no transmission through the cassava roots nor the seeds. There is an active stake business carried by the cassava traders between several provinces of Cambodia and between Cambodia and Vietnam or Thailand. Although there is clearly insect transmission happening, it is believed that currently the disease is mostly spread through stakes. Considering the importance of cassava in the region (>55 million tons / year in 2016 and >10 billion dollars business) urgent action is needed to stop the spread and put CMD under control. In September 2018, a regional workshop was carried by GCP21 and CIAT in Phnom Penh, Cambodia with the participation of the 4 countries: Cambodia, Laos, Vietnam and Thailand and a panel of international experts. There is a strong consensus to rapidly establish a regional program to control CMD through a coordinated unique plan of control. A plan with immediate, midterm and long-term actions has been elaborated and will be submitted to the four countries for approval and to donor agencies for funding. ACIAR, the Australian aid agency has already indicated willingness to support a 5 year plan and they also supported the workshop in Cambodia.

Keywords: Cassava, outbreak, mosaic, south east Asia, Cambodia, Vietnam.
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