One of the world's most important crops grown in the tropics, Cassava faces an elevated risk of being destroyed by pests and diseases because of faulty agricultural practices, scientists have warned while arguing in favour of improved international early warning system to protect farmers from emerging threats.
In a global risk assessment using a technique known as ecological niche modelling, scientists at the International Centre for Tropical Agriculture (CIAT) studied the conditions appropriate for outbreak of four formidable enemies of the crop: whitefly, green mite, cassava mosaic disease and cassava brown streak disease.
They found that the conditions are right for combined outbreaks of all four pests and diseases in some of the world's major cassava producing zones. These include Africa's Rift Valley region, much of Southeast Asia, southern India, Mato Grosso in Brazil, and northern South America.
A major cause of the rapid spread of cassava pests and diseases is the method by which the crop is propagated, with new plants grown from stakes — stem cuttings taken from older plants. As well as helping transfer infections from one generation of cassava crops to the next, the stakes are often transported very large distances — sometimes across international borders — enabling the spread of pests and diseases far beyond their geographic centres of origin, scientists asserted.
In order to protect what is arguably one of world's most important crops, it is essential to refine and enforce established protocols for the movement of stakes.
A more formal international early warning system for cassava will ensure a swift response to any outbreaks, it is argued. CIAT's cassava research program is already working to develop cassava varieties resistant to whitefly, green mite and cassava mosaic disease.
The crop is the third most important in tropical regions after rice and maize. India produces 85-95 lakh tonnes of tapioca annually mainly as smallholder cultivation.
Obviously, effective surveillance is needed to ensure disease outbreaks are either prevented or brought under control early.