Perylenequinones act as broad-spectrum fungicides by generating reactive oxygen species both in the dark and in the light.

Natural perylenequinonoid pigments (PQPs) have long been known as excellent photosensitizers. Here it is reported that PQPs, when dispersed into a micellar system, are unexpectedly very effective in inhibiting the growth of various fungi in the dark and that light can enhance the activity further. In both cases, reactive oxygen species (ROS) play a crucial role. The unique ROS-based antifungal mechanism and the excellent physicochemical properties of PQPs promise the advent of a new generation of wide-spectrum agrofungicides.