Onion white rot infects onion roots by means of appresorial formation with infection associated with a watery soft rot and formation of oxalic acid. Infected roots showed a dull mottled appearance. This project conducted a number of laboratory and glasshouse studies aimed at gaining a greater understanding of the growth of the white rot fungus, its interaction with soil fungi, and to field test several fungicides and Trichoderma for the control of white rot.