Banana disease cure renews hope of lifting export ban

Scientists have discovered a cure for the Banana Wilt disease that saw Angola and South Africa ban Kenyan exports.

They have settled on a genetic material from green pepper to treat the disease — a move that could reverse the embargoes and increase supplies to local markets.

The disease that hit Africa’s banana growing areas, including Kenya, leading to huge losses cannot be treated by pesticides and has no bio-control agents or resistant varieties that can control its spread, scientists from International Institute of Tropical Agriculture said.

The disease costs farmers about Sh40 billion every year across East and Central Africa, the scientists said.

Angola late last year banned banana imports from Kenya to curb the spread of the disease, which entered the country in 2001 through Uganda — a major import market.

The disease causes the fruit to ripen prematurely, forces leaves to wilt and the affected plants usually die leading to significant yield loss.

Banana’s importance as a food crop and for sale is growing in the region, but threats from diseases mean that farmers are unable to benefit.

Growing demand in Kenya has seen prices increase by 36 per cent for cooking bananas and 38 per cent for ripe bananas over the last three years.

Data from the Ministry of Agriculture shows that the price of cooking bananas (22kg bunch) has increased from Sh320 in August 2007 to Sh550 in August 2010 in Nairobi, while the price of ripe banana (14kg bunch) has increased from Sh400 to Sh650 in the same period.

East Africans eat an average 300 kilogrammes of bananas every year and 4.5 million farmers benefit from the crop, according to a research by Rockefeller Foundation, Africa Harvest and Technoserve.

Long way

Crops scientists drawn from across the continent announced the successful transfer of green pepper genes or DNA to bananas, enabling it to resist one of the most devastating diseases of bananas in the Great Lakes region.

But scientists said the rewards of the new scientific discovery may take longer to be felt by farmers because of the time it takes to transfer the genes and conduct additional research on the new development.

“There is still a long way to go before the transgenic bananas find their way onto farmers’ fields. But it’s a significant step in the fight against the deadly banana disease,” said Dr. Leena Tripathi, a biotechnologist with International Institute of Tropical Agriculture (IITA).

Scientists say the transformed bananas infused with one of two proteins from the green pepper, have shown strong resistance to Xanthomonas wilt in the laboratory and in screen houses. The researchers will begin confined field trials in Uganda soon.

The Ugandan National Biosafety Committee has already approved the tests.

The novel green pepper proteins that give crops enhanced resistance against deadly pathogens can also provide effective control against other BXW-like bacterial diseases in other parts of the world. Scientists said the mechanism known as hypersensitivity response also activates the defences of surrounding and even distant uninfected banana plants leading to a systemic acquired resistance.

The genes used in the research were acquired under an agreement from Academia Sinica in Taiwan.

The highly destructive BXW affects all varieties, including the East African Highland bananas and exotic dessert, roasting, and beer bananas.

The crop is also under threat from another deadly disease, the banana bunchy top.

Dr. Tripathi says that there are presently no commercial chemicals, biocontrol agents or resistant varieties that can control the spread of BXW.