According to a study published in the May issue of the Plant Disease Journal, food security for about 100 million people and income to millions of farmers in the Great Lakes region of East and Central Africa face great threat from the deadly disease.

BXW, a bacterial disease caused by Xanthomonas campestris pv. musacearum was first reported in Uganda in 2001. It has since been reported in DR Congo, Rwanda, Tanzania, Kenya and Burundi, which together constitute the largest banana-producing and consuming region in Sub-Saharan Africa.

“BXW attacks all banana varieties resulting in absolute crop loss in some cases. Its impacts are both extreme and rapid,” says Dr. Leena Tripathi, the study's corresponding author and a scientist at the International Institute of Tropical Agriculture (IITA).

The study, entitled Xanthomonas Wilt – A threat to Banana Production in East and Central Africa, was jointly undertaken by researchers at IITA and Uganda’s National Agricultural Research Organization (NARO).

The disease causes yellowing and wilting of the leaves, uneven and premature ripening of the fruits and eventually, the plants rot to their death as the deadly BXW bacteria overwhelms them.

Causes

In Uganda, between 2001 and 2007, BXW spread from central parts of the country where bananas are grown for subsistence, into more than 35 districts in areas of intensive banana production. In some parts, the disease attacked 60% of the bananas grown.

BXW is spread by insects, wind-driven rainfall, infected planting materials and contaminated planting tools.

The disease can be contained through improved agricultural practices – planting clean materials, disinfecting farm tools and early removal of male flowers. However, once a field is infected, all banana plants should be uprooted and buried and the land left fallow or planted different crops for six months.

Awareness campaigns, advocacy and support from policy makers and the donor community are critical to help mitigate its impact on affected farmers and their households, the study says.

A task force set up by the Ugandan government in 2001 in response to the outbreak of the disease reduced the disease incidence to less than 10% in areas where farmers adopted these measures. However, the implementation is not sustainable due to the high costs.

Development of disease resistant varieties is another cost-effective and sustainable way to manage the disease. However, traditional breeding methods are less profitable as they take longer to achieve usable output.

According to the study, genetic modification offers a low-cost and timely solution to the farmers who are reluctant to use labor-intensive control measures.

Researchers from IITA in partnership with NARO-Uganda, African Agricultural Technology Foundation (AATF) and Academia Sinica, an academic research institution in Taiwan, are working on improving the resistance of the local farmer’s preferred banana varieties to BXW attack by introducing disease resistant genes derived from sweet pepper. Testing the resistance of these improved bananas under laboratory conditions is underway.