Diehliomyces microsporus

False Truffle, Compost Truffle

The cause of false truffle disease of cultivated Agaricus: a heat-loving ascomycete that forms firm, brain-like truffle masses at the compost-casing interface. Mushroom spawn disappears where it grows, and infection between spawning and a few days after casing reduces yield. Its ascospores are long-lived and very heat-resistant, so once a farm is contaminated it is hard to get rid of.

Species profile

Edibility

Not edible

Not edible; a crop competitor. No toxicity documented.

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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 Entries are compiled from cited sources and reviewed, but may be incomplete or out of date — check the sources, and never rely on this library alone to identify or eat a mushroom.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

Compost and casing of cultivated Agaricus; ascospores persist in soil and in wooden trays and equipment.

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Characteristics

Mycelium: fluffy white wefts turning creamy yellow, mostly where compost meets casing. Fruit bodies: firm, wrinkled masses about 0.5-3 cm, like small brains or peeled walnuts, turning pink to reddish-brown, then drying and breaking down into a powder that smells of chlorine. Compost: dull brown or black and soggy in affected patches. Temperature: mycelium grows best around 26-32 C. Ascospores were killed by 70 C for 3 h, 80 C for 1 h or 85 C for 30 min.