CABI News

CABI is working in partnership to step up the fight against a range of devastating potato diseases which are threatening to decimate the yields of nearly a million smallholder farmers in Kenya.

Dr Joseph Mulema, Senior Scientist, Research – who is based at CABI’s centre in Nairobi, is leading a team of scientists are conducting a surveillance exercise to identify and map the distribution of Pectobacterium and Dickeya species which cause blackleg and soft rots and Clavibacter michiganensis subsp. sepedonicus which cause ring rot.

The project, which is funded by Wageningen Centre for Development Innovation, is expected to fill gaps in data availability on disease prevalence, provide a regulatory framework for certification and recommend measures for better management and control of the diseases.

Potato is a key crop in Kenya’s economy, contributing almost USD 30 million annually. The sector employs approximately 3.3 million people, of which around 800,000 are smallholder farmers – the majority of whom are rural poor and involved directly in production, and it has been prioritised by the Agricultural Sector Transformation and Growth Strategy.

However, production has consistently reduced over the last decade from 22 t/ha in 2008 to 8.6 t/ha in 2018. Kenya is the fourth highest potato producing country in Africa after Algeria, Egypt, and South Africa but with the lowest yield per acre amongst these countries. The country also has the fourth lowest yield (8.6 t/ha) in East Africa, marginally better than Uganda at 4.3 t/ha.

Dr Mulema, working with partners including the Ministry of Agriculture Livestock and Fisheries, Kenya Plant Health Inspectorate Services (KEPHIS), Kenya Agricultural and Livestock Research Organization (KALRO), International Potato Center (CIP), National Potato Council of Kenya (NPCK), University of Nairobi and TechnoServe, Kenya said, “Pests and diseases contribute to an estimated 80% reduction in production which threatens improved seed availability and food security. Some of the diseases are difficult and expensive to manage and there is limited information on their nature, occurrence, and impact.

“Given that farmers recycle their seeds, potato diseases have spread to most of the traditional potato producing regions, limiting availability of disease-free zones for improved seed production.

“However, not only is there low availability of disease-free seed but poor agronomic practices, declining soil fertility, low usage of agro-inputs and abiotic factors such as drought, as well as high pest incidence, all contribute towards declining yields.”

Dr Mulema added that information gained from the project is important to allow for the detection and monitoring of target pathogens, preventing their introduction or managing them if present, as well as supporting market access and trade in potatoes.

“We hope that the aims of the project will ultimately promote trading partners’ confidence by ensuring the availability of current and reliable information on the status of the target pathogens in Kenya; update the regulated pest list and technically justifiable import requirements for the host commodity,” Dr Mulema said.

So far, the project has developed a protocol for the identification of blackleg, tuber soft rots and ring rot diseases of potato. This was followed by a fact-finding mission which aimed at explaining the rationale of the potato disease surveillance exercise and shared the surveillance protocol with officials from the six selected counties (Elgeyo Marakwet, Meru, Nakuru, Narok, Nyandarua, and Trans Nzoia),

The project team also ascertained facts about potato production and associated pests and diseases with specific reference to the target diseases in the county, identified potato growing areas within the county suitable for undertaking the surveillance work and agreed on timelines and personnel to be involved.

Currently, the project has isolated bacterial isolates from more than 3000 samples (plant stems, tubers, and soils) which are undergoing molecular diagnostic tests. All the positive strains will be purified and preserved for future studies.

Additional information

See the project page ‘Surveillance of potato diseases in Kenya’ for further information including the full list of partners.