Mapping bacterial wilt in Uganda

Bacterial wilt is a serious threat to potato production in Uganda, and throughout Africa. But thanks to a new mapping project from the International Potato Center (CIP), smallholder farmers may soon have strategies and systems at hand to fight this persistent disease.

Bacterial wilt limits potato yields and degrades seed quality from generation to generation.

First documented in Uganda in 1958, bacterial wilt is widespread in Uganda, limiting yields and degrading seed quality. But little is known about the extent of the disease and the type of pathogen strains involved in the epidemics of disease. With potatoes, bacterial wilt is not always physically apparent: the harvest can look healthy, but the crop will not be fit as a seed for the next planting season.

This combination of yield and seed quality issues for potatoes translates into larger concerns about food security and boosting local incomes.

The issue is a lack of surveillance. “There has been no systemic monitoring and documentation of bacterial wilt in Uganda, so we set out to map the incidence and patterns of its movement,” said Kalpana Sharma, a pathologist with CIP.

Bacterial wilt is a seedborne disease, spreading easily from farm to farm and even country to country. Many African countries do not have measures in place – like quarantine – to prevent its spread. Furthermore, countries like Uganda do not have certified seed systems that can help with seed quality and health control issues.

Sharma and her colleagues conducted a nationwide survey to chart the prevalence and spread of bacterial wilt in Uganda, as well as the type of pathogens present. They worked from a hypothesis that the disease was moving primarily through seed.

The survey results would confirm that hypothesis. Bacterial wilt was present in 73% of ware potato farms and 50% of seed potato farms. The movement of disease has gone from eastern and western regions to the northern region where potatoes have been more recently introduced.

The policy implications of this study are key to improving food security in Uganda and other East African countries. “Because we have provided evidence about the types, presence, and movement of bacterial wilt, the researchers and policy makers can use this information to develop appropriate disease management strategies within seed regulatory framework,” according to Sharma.

Now completed, the Uganda study is being compared with the findings of a similar study in Ethiopia, Kenya and Rwanda. Sharma says the next steps will be to scale up this study into other countries, such as Tanzania and Malawi, to generate a bacterial wilt regional map that can inform agricultural policymakers for improved collaboration across national borders.

The full journal article is available here.

This study was funded by the German Federal Ministry of Cooperation and Economic Development (BMW) and undertaken as part of CGIAR’s research program on Roots, Tubers, and Bananas (RTB).