By Obiabin Onukwugha
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Cassava is a food crop with large edible roots. When harvested the roots can be used to produce foods such as garri, fufu, flour, amongst others.
For many smallholder farmers in Nigeria and other African countries, this food crop is a source of economic sustainability.
But this all-important food is prone to destruction. Severe floodings in Nigerian communities destroy cassava farms, thereby exercebating hunger levels among residents.
This is also the case in Kenya where this starchy crop is being threatened by disease and pests.
Cassava is the second most important food in Kenya’s western and coastal regions, after maize and feeds over 500 million people in sub-Saharan Africa.
But, new research offers hope for both farmers and consumers.
In a recent study titled “Occurrence and Distribution of Major Cassava Pests and Diseases in Cultivated Cassava Varieties in Western Kenya,” scientists from IITA and the Kenya Agricultural and Livestock Research Institute (KALRO) conducted field surveys across six major cassava-producing counties to understand how two devastating diseases, Cassava Mosaic Disease (CMD) and Cassava Brown Streak Disease (CBSD)—and pests like whiteflies and cassava green mites (CGM) are affecting cassava production.
The discoveries by these group of scientists highlight both the challenges and potential solutions to these “invisible” enemies.
Accordong to a report published on iita.org, CMD and CBSD are spread by whiteflie, tiny insects that feed on cassava plants, while CMD causes yellow, twisted leaves, stunting plant growth, while CBSD, which causes extreme yield loss results in brown streaks inside the cassava roots, rendering them unmarketable and inedible. These diseases are a major cause of food loss in the region.
As reported by the organisation, the surveys conducted in 2022 and 2023 revealed that CMD is widespread, but thanks to improved cassava varieties, it is not as rampant as it once was.
One of the scientists and Senior KALRO researcher, Vincent Woyengo, said, “KALRO improved varieties are tolerant to the effects of the major cassava virus diseases as well as being high yielding and adapted to environments in western Kenya. However, KALRO is keen to build on improved variety adoption by strengthening seed delivery systems, improving marketing structures, and training farmers in good agricultural practices.”
However, this multiple-front fight involves more than just disease in the country as whiteflies are multiplying rapidly, with 28% of surveyed fields in 2023 showing alarming infestations.
CGMs are another threat, with their numbers increasing due to unpredictable weather, potentially linked to climate change. These mites feed on young cassava leaves, slowing plant growth and reducing yields.
IITA Vector Entomologist Everlyne Wosula, who led the survey team, emphasized the urgent need to re-establish routine surveillance of plant pests and diseases.
She said the reemergence of CGM despite previous biocontrol efforts calls for immediate research to understand the resurgence and to develop effective control measures.
This is crucial, as cassava is being championed as a climate-resilient crop for food security, yet it remains vulnerable to pest outbreaks, especially under dry conditions.”
This study highlights these ongoing threats to cassava production in western Kenya, but there is good news.
The extensive adoption of improved varieties like MM96/4271 showed promise in reducing the impact of these diseases. The scientists therefore believe they can reduce crop losses and ensure cassava’s future as a reliable food source by developing disease-resistant strains and promoting better seed systems, thereby expanding the adoption of improved varieties, developing IPM strategies, and enhancing cassava’s resilience to both pests and climate-related stressors.
