Electron Microscopic Analysis of the Penetration Process ofFusarium nygamai,a Hyperparasite ofStriga hermonthica

Abstract In a previous study we showed that the facultative fungal parasite Fusarium nygamai was able to reduce the germination of seeds of the root-parasitic weed Striga hermonthica and kill more than 70% of the germinated Striga by attacking the parasite's germ tube. As a result, Striga emergence was reduced by about 90%. We are now providing electron microscopic evidence of the infection process. The free, mature conidia of the fungus was able to infect S. hermonthica. The mycelium penetrated the seed coat and destroyed the endosperm. The fungus was also detected in the weed's germ tube. As a soilborne pathogen, F. nygamai could be very effective in controlling the parasitic weed since Striga seeds are attacked underground. A further advantage is that the application of the fungus as a bioherbicide could be done to any crop under crop rotation.