In 2003, when the New Partnership for Africa’s Development (Nepad) and the International Food Policy Research Institute championed the humble cassava as the key to future food security in Africa, little did they know that they had a willing and able ally at the University of the Witwatersrand in Johannesburg — Professor Chrissie Rey of the school of molecular and cell biology.
Rey heads a Thrip-funded research project aimed at ultimately putting cassava on the map as Africa’s leading subsistence and commercial crop. Cassava, Manihot esculenta, otherwise known as yucca or manioc, is cultivated in more than 80 countries across the world.
A native of South America, this woody shrub’s roots are the thirdlargest source of carbohydrate for human food. When dried and ground into a flour known as tapioca, cassava root is turned into a porridge rather like mealie pap.
‘It’s a hardy plant,” says Rey. ‘It tolerates drought conditions and grows in a variety of soil types. The roots can be left in the ground for long periods of time, meaning that they offer excellent food security to those who don’t have food storage facilities.”
Rey says that cassava’s benefits as a subsistence crop are considerable. ‘The roots are used for a wide range of products for food and industrial uses and the waste material from processing can be used as animal feed,” she says, adding that the plants themselves shed their leaves during their growing period, creating a source of organic nutrients, which can be used as fertiliser.
Although cassava usually yields up to 80 tonnes of its precious roots a hectare in other growing areas, in Africa this figure drops to around nine tonnes a hectare. ‘Africa produces more cassava than any other continent, but our yields are surprisingly poor,” says Rey. Why?
Cassava mosaic disease (CMD), caused by a serious group of virus pathogens, can cause crop losses of up to 60%. With the support of the locally based Casquip Starch South Africa, Rey envisages a time when the war against CMD will be won. It’s a global effort too.
Rey’s team works with researchers at the International Centre for Tropical Agriculture, the University of Jerusalem and the University of Eduardo Mondlane in Mozambique.