Isothiocyanates inhibit fungal pathogens of potato in in vitro assays: Isothiocyanates produced by Brassica spp. inhibit growth of three economically important potato pathogens

Aims: This study aimed to examine the effects of seven different isothiocyanates against the growth and development of three important soil borne potato pathogens, (Colletotrichum coccodes, Rhizoctonia solani and Helminthosporium solani). Methods: The study was carried out using an agar diffusion assay. The radial growth of fungal pathogens grown on agar containing different ITCs at a range of concentrations was compared to that of growth on control agar plates that did not contain ITCs. Results: Results varied depending on the specific isothiocyanate incorporated into the agar. They ranged from those which showed a significant effect on fungal growth to those which appeared to have little or no effect. Where a suppressive effect was observed, due to the presence of the isothiocyanate, fungal colony growth decreased as the concentration of the incorporated isothiocyanate increased. Conclusions: Results from this study indicate that fungal growth can be inhibited by exposure to ITCs. However the results observed are specific to the ITC structure and exposure concentration.