The fungus behind wet bubble disease ("Mycogone"), one of the most damaging diseases of the white button mushroom, Agaricus bisporus, wherever it is grown. It attacks fruit bodies rather than the mycelium: infected pins become soft, shapeless masses of tissue (sclerodermoid mushrooms) that ooze amber droplets and rot with a foul smell, while later infections cause cap spots and distorted mushrooms. Long known by its asexual name, Mycogone perniciosa.
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Mycology is an evolving science: names, classifications and safety information change as research advances. Entries are compiled from cited sources and reviewed, but may be incomplete or out of date — check the sources, and never rely on this library alone to identify or eat a mushroom.
Habitat
Soil-borne mycoparasite of Agaricus fruit bodies, chiefly cultivated A. bisporus. Enters farms with contaminated casing or casing ingredients (soil, lime), dirty water, dust and debris; then spreads by water splash, equipment, hands and spent material.
Distribution
Reported wherever Agaricus bisporus is cultivated, including Europe (e.g. Poland, Ireland, UK), North America and Asia (China).
Characteristics
Symptoms: large, undifferentiated, irregular tissue masses; white fluffy mycelium on affected mushrooms that can grow out onto the casing and turns brown as spores mature; amber liquid droplets at high humidity; wet rot with an unpleasant odor. Dry bubble (Zarea fungicola, formerly Lecanicillium/Verticillium) looks similar but stays dry and leathery without ooze or smell; lab confirmation is sometimes needed. Spores: two types, small fragile short-lived conidia and large thick-walled, two-celled aleuriospores (chlamydospores) that persist in casing, soil and water. Pathogenicity: degrades A. bisporus basidiomes directly; no pathogenic activity on the vegetative mycelium (Zhang et al. 2021). Genome about 44 Mb, closely related to Cladobotryum protrusum (Li et al. 2020).
