Abstract: A method for the screening of potential antifungal agents comprises testing the inhibitory effect of the potential antifungal agent in two tests, a first test for inhibition of pathogen development in sterilised soil infested with mycelium of Pythium spp and a second test against for inhibition of disease development in a growing plant of a species susceptible to disease from damping-off disease complex in the presence of the said complex, identifying agents giving potential inhibitory effect in both tests compared with control and submitting same for further examination. Using this method four particularly useful microorganisms which display antifungal activity in a wide spectrum, shown in further testing and in field trials, of disease fungi have been provided. Methods of using such microorganisms and compositions and compositions containing same are also described.