Hypomyces chrysospermus - Mushroom ParasiteWhitish at first, diseased mushrooms turn bright golden yellow as they are overrun by the parasite. The fungus produces massive numbers of asexual spores (conidia) that appear like yellow dust over the surface of the host. A common and widespread parasite, it is especially attracted of boletes, during prolonged wet periods. Below: The asexual conidial state of Hypomyces chrysospermum forms bright yellow aleuriospores that give the diseased mushroom a distinctive colour, often in patches of the surface of the host.. The asexual (=conidial) state is known as Sepedonium chrysospermum
Spededonium chrysospermum is the asexual (or conidial, or anamorphic) state of the sac fungus Hypomyces chrysospermum (Pyrenomycetes, Ascomycota). The spores are one-celled aleuriospores that originate as blown out ends of short, lateral, fertile branches. The mature spores (conidia) are large spherical, thick-walled, yellow, and have a roughened, warty (tuberculate) outer wall. They are produced in such abundance that infected mushrooms are covered with a powdery layer of yellow spores as seen above.