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IITA and its partners have found a way to control the scourge of witchweed (Striga hermonthica) in Sub-Saharan Africa through a biocontrol agent. Striga infests some 50 million hectares of cereal crops, specifically maize, sorghum and millet, causing farmers an estimated US$ 7 billion in annual losses and affecting over 300 million people in the region.

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Developed by a team led by IITA plant pathologist Dr. Fen Beed with partners from the University of McGill (Canada) and University of Hohenheim (Germany), the technology utilizes certain strains of Fusarium oxysporum (F. oxysporum) to fight the parasitic weed. The technology is cheap, environment-friendly and safe as the fungus specifically targets witchweed.
The fungal strains tested originated from Ghana, Mali and Nigeria but, like witchweed, they are common throughout semi-arid Africa. The fungus can be easily grown in sterile water containing sorghum waste. The hard part was finding a way to coat seeds with it.
Through experimentation, the team found that spores of the fungus can be mixed with liquefied Arabic gum – an organic adhesive extracted from trees and commonly found in many SSA countries – without harming the fungus. The mixture is coated onto the seeds, dried then planted. The fungus remains viable for long periods, making the seeds amenable to storage. The fungus could also be directly dispersed into soil holes where the seeds are to be planted. The treated seeds produce crops that are free of the parasitic weed.
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