Trichoderma Cap Spotting

Trichoderma is often associated with green mould outbreaks in compost caused by Trichoderma aggressivum. However, a different and often less obvious problem occurs when other Trichoderma species become established in the casing layer. Species such as Trichoderma atroviride, T. aureoviride, T. hamatum, T. harzianum, T. imhamatum, T. virens, T. koningii and T. longibrachiatum are commonly encountered in Agaricus bisporus mushroom farms (Fletcher and Gaze 2008). Unlike T. aggressivum, these fungi may not cause catastrophic crop failure, yet they can become persistent casing contaminants that are one of the primary causes of cap spotting, resulting in reduction of quality and marketable yield.