Picture: REUTERS
Picture: REUTERS

Makoni, Zimbabwe — For years, Selina Moyo did not waste maize grain that went mouldy. While her family may not have eaten it, she would throw it to the chickens or allow cattle to nibble on it. Not anymore.

Farmers in Zimbabwe and across Africa routinely lose their crop to pests. In addition, poor drying and storage attracts a more serious health risk: aflatoxin contamination. These are naturally occurring poisons produced by certain species of fungi which infect crops in the field, before or after harvest and during storage.

Exposure to aflatoxins has been linked to stunting of childhood growth, liver cancer, and immune suppression in adults, yet there is a general lack of awareness in farming communities across Africa about this threat to health, food security and trade.

Hermetic storage in the form of thick, plastic "super-bags" and the metal silos have proven effective against pests and in reducing aflatoxin contamination, a new study by researchers in Zimbabwe has found.

Moyo, a mother of three, is one of 260 smallholder farmers in Makoni district in Zimbabwe’s Manicaland province, who received super-bags to determine if improved storage can reduce aflatoxin contamination in local maize grain.

The super-bags, together with metal silos, were given to farmers under a two-year project costing $1.6m. It is supported by the Cultivate Africa’s Future programme, an initiative funded by Canada’s International Development Research Centre, and the Australian Centre for International Agricultural Research.

The project used a randomised control trial to test the efficacy of metal silos and the super-bags against the use of conventional storage methods such as polypropylene bags and mud huts.

Maize accounts for almost 90% of the daily meals consumed in the country. Zimbabwe — which, in 2017, recorded a bumper maize crop of more than 2-million tonnes — is among the top five countries in Africa which consume the highest amount of maize per capita.

Aflatoxin contamination affects humans and animals that eat contaminated foods such as maize grain, cassava, sorghum, yam, rice, groundnuts and cashews, which are most susceptible to poisons.

The study by University of Zimbabwe and Action Contre la Faim (Action Against Hunger) researchers under a two-year project has confirmed high level of exposure to aflatoxins among farmers in two key maize growing areas of the country.

Despite maize being a strategic crop in Sub-Saharan Africa, farmers lose up to 30% of harvested maize every year to pests and poor post-harvest handling. Zimbabwe loses more than $50m worth of maize annually during storage alone, according to the ministry of agriculture, mechanisation and irrigation development.

Agriculture extension officers say smallholder farmers in Zimbabwe have problem storing the maize, which is affected by the notorious pest, the large grain borer. Such pests help create conditions conducive for aflatoxin contamination.

Dr Loveness Nyanga, the project principal investigator and researcher at the University of Zimbabwe, says the first-time study found that farmers had little knowledge on aflatoxins and the health risks associated with consumption of aflatoxin-contaminated food.

"With the use of hermetic technology farmers are able to hold on to their grain during the peak season and sell it when it is on demand or any other time to anyone who can offer the best price," said Nyanga. He contrasts this with "being forced to sell at a going rate price because of fear of losing the quality of grain due to poor storage facilities".

Nyanga adds: "During the lean period, maize grain from hermetic technology would sell at $7 to $7.50 (for a 20kg bucket) because of the quality; and maize grain from conventional stores would sell at $4 to $5.50."

Zimbabwe is currently drafting a post-harvest policy and the management of the mycotoxin will reduce public health risks associated with the consumption of aflatoxin-contaminated food.

Aflatoxin contamination is also a trade obstacle in Africa. The continent loses more than $450m annually when its commodities are rejected on global markets because of high contamination levels, according to the Partnership for Aflatoxin Control in Africa, an initiative of the African Union Commission.

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