The two most difficult to control compost pathogens of the common mushroom, Agaricus bisporus, are Trichoderma aggressivum, the cause of compost green mould, and mushroom virus X (MVX). The chemicals used to control the former (formaldehyde and carbendazim) are no longer approved for use on mushroom crops in the EU, and nothing is available for the effective treatment of the latter. The EU-funded project MUSHTV (Solutions for the mushroom industry to emerging disease threats from Trichoderma and virus) worked to provide new information about these compost-related diseases, as well as diagnostic tools. Researchers found several promising disinfectants that could kill spores of both T. aggressivum and A. bisporus ( which can transmit viruses) in the laboratory. However, when the organisms were within compost particles it was difficult to kill A. bisporus and extremely difficult to kill T. aggressivum, highlighting the importance of thorough cleaning and hygiene regimes. Research into Bacillus subtilis as a biocontrol agent for T. aggressivum yielded unsuccessful results when used with bulk incubated compost. B. subtilis and a second biocontrol agent were also ineffective against other mushroom pathogens (dry bubble, wet bubble and cobweb) but the active ingredient metrafenone was shown to give good control. Some EU countries have given approval for its use. Further research is needed to identify effective biocontrol agents. Another part of the project looked at the genetic characterisation of viruses in mushrooms infected with MVX. The team identified 17 different viruses, 16 of which are new to science, highlighting some of the challenges facing the industry. Researchers also investigated the rate and pattern of T. aggressivum spread in mushroom compost tunnels. The technologically advanced practice of ‘bulk handling’ compost was shown to exacerbate the effect of a small local infection, highlighting again the importance of thorough cleaning and hygiene regimes. Results showed that volatile organic compound profiles in pilot bulk incubation compost tunnels can identify the presence of T. aggressivum. It is not known whether detection is also possible in industrial tunnels. This knowledge has contributed to the development potential of new volatile-based diagnostic tests. Project partners have provided new technical knowledge and advice for the mushroom industry, in the form of factsheets, workshops and seminars. They have also developed advanced diagnostic methods to detect both T. aggressivum and MVX. MUSHTV results will make the mushroom industry as a whole more knowledgeable and more efficient at dealing with disease threats, thereby reducing their reliance on and use of pesticides. This has important economic benefits for the industry. Reduced pesticide use also has a positive social and environmental impact with regard to high-quality food and protection of the environment.
Mushrooms, compost, Trichoderma aggressivum, mushroom virus X, MUSHTV, compost tunnels