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Weeding out Africa's witch plant

Striga invasion is responsible for up to US$1.2 billion in crop losses in sub-Saharan Africa (© IITA)
Striga invasion is responsible for up to US$1.2 billion in crop losses in sub-Saharan Africa

A multi-million project has been launched to control Striga, the parasitic weed scientists blame for up to 80 per cent yield loss of Africa's staple crops, such as maize and cowpea. The US$9 million project will focus on improving and expanding access to methods of Striga control in Nigeria and Kenya, while supporting research to identify the most effective means of controlling the parasitic weed. As a consequence, by 2014, the International Institute for Tropical Agriculture (IITA) estimates that over 250,000 individual farmers will enjoy up to 50 per cent higher maize yields and 100 per cent higher cowpea yields. This should generate an estimated $8.6 million worth of additional grain annually at the project locations - resulting in increased incomes, better nutrition, and reduced poverty, as well as employment opportunities ranging from grain production to food markets.

The weed, which occurs throughout Africa, is a challenge to control because it is a prolific seed producer, each plant producing up to half a million seeds that can remain dormant in the soil for decades. According to researchers at IITA, Striga invasion is responsible for up to US$1.2 billion in crop losses for farmers and affects approximately 100 million people in sub-Saharan Africa. The project will implement and evaluate four approaches: using Striga-resistant crop varieties; using a "push-pull" technology that involves intercropping with specific forage legumes that inhibit the germination of Striga; using herbicide-coated seeds; and deploying bio control of Striga.

Prasanna Boddupalli, director of the Global Maize Program of CIMMYT, based in Nairobi, Kenya, says the project aims to integrate delivery of Striga-resistant maize and legume seeds with best-bet agronomic technologies to fight the weed menace, while raising farmers' awareness of the technologies, and supporting community-based organizations with technical assistance.

Lessons and strategies from the project will be applied in replicating the project in other areas of sub-Saharan Africa. Witch weed primarily affects smallholder farmers who cannot afford costly herbicides for fighting the parasitic plant. It is estimated to have infested up to 4 million hectares of land under maize production in sub-Saharan Africa. "Africa is plagued by a plant 'vampire' that robs farmers of their harvest," says Hartmann, IITA director general. "Dedicated pursuit by farmers and researchers is delivering several ways to fight the parasite."

* The project is supported by a US$6.75 million grant from the Bill & Melinda Gates Foundation

Written by: Busani Bafana

Date published: June 2011


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