Differential responses of ectomycorrhizal fungi to pesticides in pure culture

The effects of several fungicides and herbicides on the growth of the ectomycorrhizal fungi Lactarius deliciosus, strain LDF5, and Pisolithus tinctorius, strains 30AM, 3SR and Mx, in pure culture were studied. The products tested were selected because they are commonly used in nurseries and afforestation practices. Five concentrations (0, 1, 10, 100 and 1000 mug/g) of each fungicide (benomyl, captan, hymexazol, iprodione, propamocarb hydrochloride and thiram) or herbicide (glyphosate, hexazinone and simazine) were prepared. Fungal growth was evaluated as colony diameter, mycelial biomass, and morphological features. Propamocarb hydrochloride was the most tolerated fungicide. Benomyl, captan and thiram reduced mycelial growth at concentrations above 100 mug/g. Hymexazol and iprodione had the highest inhibitory effect. In contrast, the herbicides produced little or no effect and they even stimulated the growth of L. deliciosus.