Farmerparticipatory onfarm evaluation of Striga hermonthica management options in the Nigerian northern Guinea savanna pilot site of the SPIPM - Emechebe, A.; James, B.; Atala, T.; Kureh, I.; Hussaini, M.A.; Singh, B.; Menkir, A.; Voh, J.; Ado, S.; Alabi, S. (2003)