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Uprooting cassava disease: Scientists identify causes of two devastating crop diseases

Across the tropics, farming communities—an estimated 800 million people—rely on cassava for food and income. However, in recent decades, harvests have been decimated by rapidly spreading diseases. But there is good news for cassava breeders and farmers.

In a series of studies published in Scientific Reports and New Disease Reports, researchers have established the pathogens and the first diagnostic tests for two diseases: Cassava Frogskin Disease and Cassava Witches' Broom Disease. This milestone achievement could revolutionize cassava disease management across Latin America and the Caribbean as well as Southeast Asia, where farmers and researchers have been working side-by-side to fight the spread of these diseases for decades.

Scientists were able to make these discoveries thanks to a multidisciplinary approach that combined classical plant pathology, metagenomics, bioinformatics, and epidemiology. The scientific team behind this work was led by Dr. Wilmer Cuellar, from the Alliance of Bioversity International and CIAT, whose research on crops spans the globe.

Every opportunity to recognize and stop the pathogens earlier is critical, says Cuellar, "Preemptive research at the Alliance's Cassava Program is key to reducing the negative impact of these diseases in regions where they are yet to arrive, such as Sub-Saharan Africa."

Key findings include:

• Cassava Frog Skin Disease (CFSD), responsible for significant crop losses across the Americas, is a viral disease associated with previously unidentified torradovirus infections.
• Cassava Witches' Broom Disease (CWBD), a harvest-reducing pathogen originating in Southeast Asia, has crossed the Pacific and has been detected in French Guiana and Brazil. It is a fungal disease linked to Ceratobasidium theobromae.

As a result of this research, crop specialists and national institutions are already deploying tests to:

1. Certify cassava seeds as disease-free;
2. Monitor disease spread and pathogen evolution;
3. Identify resistant cassava varieties;
4. Guide targeted chemical control measures.

Scientific research informs a rapid response. "Solving these puzzles required years of patient collaboration and cutting-edge science. Now, we are equipped to tackle these diseases head-on and safeguard cassava production for future generations," said Cuellar.