Green mould (Trichoderma aggressivum var. aggressivum)
This fungus is soil-borne. There are many species of the fungus but Trichoderma aggressivum var. aggressivum (Trichoderma harzianum biotype 4 (Th4)) is a major problem particularly to button mushrooms. It gains entry to growing rooms primarily through contaminated personnel and equipment. Other sources include poorly composted substrate or carryover in rooms that were not sufficiently steamed off. Once introduced, it rapidly spreads into large disease areas from infection source. Infection of casing soil can result in serious losses. Green mold is characterized by dense white mycelial growth followed by extensive green patches on casing/compost or mushroom caps. The spores of the fungus are sticky and can easily be spread by flies, mites and workers to previously uninfected area. Red pepper mites are often associated with the disease.
- Maintain hygienic conditions at all stages of production
- Use properly prepared substrate and casing soil that have been adequately pasteusterized
- Remove contaminated substrate as soon as possible from the farm and dispose of it at a considerable distance nor less than 100 metres
- Control flies and mites
- Spread table salt on the compost in affected areas when green mold is first recognized.
- Filter air to prevent colonization of sterilized compost
- Disinfest all structures and equipment (including clothing) associated with spawning (use immediately after disinfestation or store where air is filtered).
