Spread of cassava disease causes concern in EAC
David Musyoka The Citizen, Dar es Salaam, Sunday, 20 November 2011
United Nations food experts are concerned about a new variant of a cassava disease
which they said is affecting large parts of East Africa, especially in the area's Great Lakes
region, putting a crucial source of food and income at risk.
The experts from the UN Food and Agriculture Organisation say the cassava brown
streak disease (CBSD) is on the verge of becoming an epidemic, and have called for an
urgent increase in funding, research, training, surveillance and other measures to help
farmers and breeders.
"The disease manifests itself in different ways depending on local conditions. In some
cases it shows symptoms only on the roots," Jan Helsen, leader of FAO's European
Union-funded Regional Cassava Initiative in Eastern and Central Africa, said in a
statement issued on Wednesday in Nairobi.
"An apparently healthy plant may be found to have spoiled roots only when harvested,
with obvious consequences for food security," Helsen said.
The appearance of the disease in previously unaffected areas, and the lack of continued
funding for research and development work to address CBSD in the region, have added
to the threat already presented by the cassava mosaic disease (CMD).
In Rwanda, a surveillance analysis conducted by the National Agricultural Research
Institute in 2010 showed a 15.7 percent rate of infection on local varieties and 36.9
percent in improved varieties.
"None of the cassava varieties currently being distributed to farmers seem to be tolerant
to the effects of CBSD. We urgently need to get information on the extent and severity of
the outbreak, and to support investments to identify disease-tolerant varieties and coping
strategies for farmers," Helsen said.
One of the challenges facing those who are trying to stem the spread of CBSD is timely
detection of the disease. Cassava can account for as much as a third of the total calorie
intake for people in countries such as Burundi, Rwanda, Uganda or the Democratic
Republic of Congo (DRC).
Short-term measures needed to tackle CBSD include stepping up disease surveillance and
conducting regular inspections, increasing the sensitization of communities to the threat
of CBSD, and using hands-on training for farmers, like FAO's farmer field schools, to
introduce community-based practices to prevent the introduction or spread of the disease,
such as the removal of infected plants.
"Thanks to the foresight of, and the scientific support from, the International Institute of
Tropical Agriculture (IITA), efforts are underway to understand the epidemiology of the
disease, but more support will be needed for this work, and to select and bring on CBSD-
tolerant varieties," Helsen added.
Recommended measures also include banning the distribution of infected plants between
districts and zones, and, in the event of infection, using coping strategies such as the early
harvest of cassava, before symptoms appear and significant damage can be done.
Since around 2006, FAO and the Catholic Relief Services (CRS) have implemented two
regional cassava projects, funded respectively by the European Union and the Bill and
Melinda Gates Foundation, to support vulnerable farmers affected first by CMD and now
The projects have provided access to clean, or virus-free, planting material. The projects
aim to develop capacity in disease preparedness and strengthen the resilience of farmers
to outbreaks of both diseases.
"Fortunately, there are now eight varieties under development by IITA and its national
partners in the region which are resistant to Cassava Mosaic Disease and which show
some level of tolerance to CBSD," Helsen said. "Under existing program arrangements,
these varieties could be made widely available in the next 18-24 months, assuming that
resources can be identified to support multiplication and distribution activities," said
Helsen says National Cassava Steering Committees have been set up to manage the
response to the disease, but they need more time and funds to ensure that some of the
CBSD-tolerant varieties in the pipeline can be multiplied and made available across the
More extensive surveillance will be carried out in Rwanda again this year, along with
Burundi and the DRC, which will give a more complete picture of the occurrence and
spread of the disease.
To help raise awareness of the impact of the disease, FAO and CRS are currently
undertaking a rapid survey on the impact of CBSD on household food security across the
Cassava, together with yams and sweet potatoes are important sources of food in the
tropics. The cassava plant gives the highest yield of carbohydrates per cultivated area
among crop plants, except for sugarcane and sugar beet.
Cassava plays a particularly important role in agriculture in developing countries—
especially in sub-Saharan Africa—because it does well on poor soils and with low
rainfall, and because it is a perennial that can be harvested as required. Its wide
harvesting window allows it to act as a famine reserve and is invaluable in managing
It also offers flexibility to resource-poor farmers because it serves as either a subsistence
or a cash crop.
The writer filed this report for Xinhua from Nairobi