A team of researchers, representing the Africa Rice Center (AfricaRice), the International Rice Research Institute (IRRI) and Wageningen University, has raised the alarm over the enormous economic impact of parasitic weeds on rice production in Africa, threatening the food security and livelihoods of millions of resource-poor rice farmers and consumers in the region. The weeds threaten rice production in at least 28 countries on the continent that have rain-fed rice systems.
The most affected countries are Burkina Faso, Cameroon, Côte d’Ivoire, Guinea, Madagascar, Mali, Nigeria, Sierra Leone Tanzania and Uganda.
The team said smallholder farmers are losing every year half a million tonnes of rice worth about $200 million because of the weeds. Parasitic weeds are among the most destructive and problematic weeds to control. “When these plants invade food crops, they turn into ferocious weeds,” said Agronomist at AfricaRice, Dr Jonne Rodenburg. The most important parasitic weed species in rice are Striga asiatica, S. aspera, S. hermonthica and Rhamphicarpa fistulosa.
They are all endemic to Africa and can also parasitise other cereal crops like maize, sorghum and millet. The team of researchers reveal that these parasitic weeds, which survive by siphoning off water and nutrients from host crops, have invaded 1.34 million hectares of rain-fed rice in Africa, affecting an estimated 950,000 rural households. They are increasingly becoming severe due to an intensification of agricultural production and climate changes.
The areas affected by parasitic weeds are home to some of the world’s poorest farmers. Studies by AfricaRice and partners have shown that parasitic weeds seem to predominantly affect women farmers in Africa as they are often forced to grow rice on the most marginal and parasitic weed-infested plots. The researchers warn that these parasites are spreading fast in the rainfed rice area and if nothing is done to stop them in their tracks, the damage will increase by about US $30 million a year.
Rice is the second most important source of calories in Africa. It is also critical for smallholder incomes. Demand for rice is growing at a rate of more than 6% per year – faster than for any other food staple in sub-Saharan Africa (SSA), because of changes in consumer preferences and urbanisation. Rice production is increasing across SSA, but the continent still imports some 40 per cent of its rice.
AfricaRice and its partners have been investigating and developing efficient parasitic weed management strategies that are affordable and feasible for resource-poor rice farmers.