Abstract Hygrocybe and the other macrofungal taxa associated with low nutrient grasslands have intrigued mycologists because of the uncertainty of their trophic status. Various lines of evidence have suggested that they may be biotrophic, rather than saprotrophic. However, the mechanism of such an association is not yet established. We conducted simple field experiments aiming to shed some more light into the nutritional biology of these fungi. Application of selective biocides to small areas of turf where Hygrocybe spp. had previously fruited revealed that removal of all vegetation (glyphosate) inhibited subsequent fruiting, as did removal of grasses (Fusilade), whereas removal of herbs (Agritox) or mosses (FeSO4) had no effect. These findings are in line with a biotrophic association with grasses but the mechanism of such an interaction still eludes discovery.