Volume 19 Part 1 Article 23: Finding a Suitable Biocide for Use in the Mushroom Industry

Volume 19 Part 1 Article 23
Year 2016
Title: Finding a Suitable Biocide for Use in the Mushroom Industry
Author: Johan Baars and Jo Rutjens

As part of the EU financed project “MushTV” a variety of biocides was tested for efficacy against Agaricus bisporus (a model system for MVX infected A. bisporus) and Trichoderma aggressivum. In laboratory tests, efficacy of 12 biocides, each based on different active ingredients, was tested both at the recommended dose and time (mostly 15 minutes) and at a double dose and prolonged time (mostly 1 hour), and compared with the effectiveness of formalin (at recommended doses), the industry standard disinfectant being replaced). Disinfectants were tested against basidiospores or mycelium of A. bisporus and compost particles that were colonised by A. bisporus mycelium.

In laboratory tests, many of the disinfectants were able to kill the basidiospores and mycelium of A. bisporus at the concentrations and disinfection times tested. However, when present in compost particles, A. bisporus could only be killed effectively with formalin, and a few other disinfectants.

With respect to T. aggressivum, conidiospores were killed in laboratory tests by all disinfectants, except gaseous ozone. Mycelium of T. aggressivum could be killed by formalin, and a few other disinfectants. Neither gaseous ozone nor electrochemically activated water had any effect on mycelium. None of the disinfectants was able to kill T. aggressivum in infected compost particles.

Attempts were made to extrapolate the laboratory results to the practical conditions in commercial mushroom cultivation. Various types of surface that may occur in the mushroom industry (rubber mats, stainless steel, mats from growing rooms and tunnels, aluminium, concrete, isolation panel and coated steel) were contaminated with either basidiospores of A. bisporus or conidiospores of T. aggressivum. Based on efficacy and the lack of leaving a residue, electrochemically activated water (ECAS), a product based on hypochlorite and a product based in a combination of peracetic acid and hydrogen peroxide were selected for testing. ECAS was not very effective under these semi-commercial conditions. The products based on hypochlorite or on peracetic acid/hydrogen peroxide however, showed good efficacy. Next to this, residues of these products disappeared within hours after application.

Compost debris from infected crops holds a severe risk of spreading disease that can be transmitted by compost, such as Trichoderma and MVX. It is not possible to completely kill mycelium in compost with disinfectants. Disinfectants offer no real alternative to steam cook out to control mushroom diseases.

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