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Biological control of Striga witch weed in Kenya: from a toothpick to home-grown biocontrol inoculum.

David Sands: Montana State University

<div>Biological control of Striga witchweed in Kenya: from a toothpick to home-grown inoculum<br /="/">David Sands, Henry Nzioki, Florence Oyosi, Claire Baker<br /="/">Biological control of parasitic plants and weeds in general can be a cost-effective alternative to herbicide use in the hands of smallholder farmers. In the case of control of Striga hermonthica, a serious yield limiting parasitic weed in cereals in sub Saharan Africa, it was necessary to develop selection strategies to produce highly virulent fungal strains for control of this parasitic plant on the maize host. In addition, the fungi had to be made available and affordable to smallholder farmers in a form where they could easily produce fresh inoculum at planting. Three selected biocontrol strains of Fusarium oxysporum fsp. strigae were embedded on toothpicks and sealed in sterile drinking straws, ready to serve as an on-farm primary inoculum. These toothpicks were delivered to 500 smallholder farmers in western Kenya by a network of women trainers who incubated them in boiled rice substrate three days prior to planting. Grains of the rice inoculum were then planted with maize seeds. The resultant maize yields due to the fungi (where paired plots were both fertilized and seeded with hybrid maize) were increased by an average of 56% in the long rain season and 42% in the short rain season (p<0.0001, pair-wise t-test). Biocontrol of weeds can be inexpensive and effective if fungal strain selection and appropriate delivery systems are employed, as demonstrated in Kenya.</div>

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