New viral disease threatens East Africa’s cassava farming

Date:07-14-2009

Cassava Brown Streak Virus, a new disease that affects the tuber crop and that could jeopardise food security has been found in East Africa. The virus has the potential of becoming an epidemic.

Scientists said that the disease was first detected in Tanzania and spread to Kenya, Rwanda, Burundi, Democratic Republic of Congo, and Uganda.

The virus is spread through propagation and by a whitefly vector (bemisia tabaci) predominant in the affected countries, and is associated with the Cassava Mosaic Disease too.

It is not yet known how the disease could affect humans because research on it is still in the early stage.

Preliminary research shows that it is predominant in varieties that have been improved to resist the mosaic disease -- the worst cassava disease ever known -- a disturbing finding that could divert scientists efforts to fight the mosaic.

The improved variety was preferred by farmers who wanted to avoid the mosaic disease, which ravaged parts of Uganda in the 1990s causing starvation in some communities.
Cassava affected by the brown streak virus is brown and harder than a healthy tuber, which makes it inedible. The virus has been known to affect entire farms once it strikes, scientists said.

So far, the disease has spread to 30 districts in Uganda and in Kenya the outbreak has been reported in a large multiplication site in Yala swamp in Nyanza province. In Malawi the disease is widespread around the shores of Lake Malawi.

In Uganda, scientists are currently doing research to understand the virus, and how to develop resistant varieties.

Robert Anguzo, the spokesman for the National Agricultural Research Organisation said that a project, the Virus Resistant Cassava for Africa is currently doing research using biotechnology and conventional methods to develop cassava varieties that are resistant to both the mosaic disease and the brown streak virus.

The project will run for five years before findings are released to the public.