Chemical and biological control of cultivated mushroom diseases

Button mushroom (Agaricus bisporus) production worldwide and in Serbia has been expanded over the past decade. Introduction and spread of many fungal and bacterial pathogens results in lower yield and quality. Until recently, Mycogone perniciosa, Lecanicillium fungicola, and Cladobotryum sp., the causal agents of dry bubble, wet bubble, and cobweb disease, respectively, had been considered the main A. bisporus pathogens. Besides these pathogenic fungi, mushroom virus X and various Trichoderma species, the causal agents of green mould, have also emerged as major pathogens in the past decade. The most serious of them, T. aggressivum f. sp. europaeum, has been transmitted from the British Isles to many European countries including Serbia. In addition, the bacterial pathogen Pseudomonas tolaasii has been found to be associated with brown blotch symptoms. Only few fungicides are officially recommended in mushroom industry as a small crop: prochloraz in the EU countries, and chlorothalonil, thiabendazol and tiophanate-methyl in North America. Latterly, a decreased sensitivity of L. fungicola to prochloraz has been observed in Spain. Prochloraz inefficiency in cobweb disease control has also been recorded in Great Britain. As a result some new biological antimicrobial supstances are being tested. Biofungicides based on tea tree oil and Bacillus subtilis cause a significant reduction in cobweb and green mould disease incidences in A. bisporus growing rooms. The antimicrobial activity of many essential oils has been tested and oregano, thyme and mint oils were found the most efficient substances against various mycopathogens. Recently, an eco-friendly disinfectant based on colloidal silver and hydrogen peroxide has been found to suppress significantly the growth of P. tolaasii. Furthermore, peracetic acid has proved to be an efficient casing soil disinfectant against cobweb disease. This study was funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Project TR31043.