There is no answer for such a complex issue. Pathogens are many and complex, soil microrganism interactions are many, chemical soil interactions are complex. Consider one pathogen at a time, in a specific situation, in a specific host. Act in a multidisciplinary approach. 

I will recommend you to use propamocarb in testing. Also you can try use biological fungicides with Bacillus spp..

You may try different concentrations of Neem leaves or seed extract or as a matter of fact other biological treatment. One of the properties of Neem is that it is used as a fungicide and is effective to many species of fungal species.

But my only query is are you looking for a particular soil pathogenic fungus? or all of soil pathogenic fungi?