Pleurotus ostreatus are widely cultivated throughout Asia and its market demand is increasing day-by-day. In order to pave the way for success of this industry, one of the critical points is how to control disease during the process of production. Based on this fact, a study was undertaken to isolate various fungal pathogens of P. ostreatus and its related material from the period of December 2008 to April 2009. A total of 69 fungal isolates were obtained by processing 60 infected mushroom, spawn and substrata samples procured from nine mushroom cultivation units in Coimbatore and Erode districts. The isolates were identified as Aspergillus flavus (n = 14), Trichoderma sp. (n = 14), Rhizopus sp. (n = 12), Aspergillus niger (n = 8), Fusarium sp. (n = 2), Pencillium sp. (n = 5), Aspergillus sp. (n = 4), Alternaria sp. (n = 1) and Curvalaria sp. (n = 1) and unidentified strains (n = 8). Growth pattern of fungal isolates on Sabouraud's Dextrose Agar (SDA) and Potato Dextrose Agar (PDA) revealed the profuse growth of Rhizopus sp. and Trichoderma sp. The concentration of 0.175% of formalin could not inhibit the growth of the fungal isolates but have an effect in sporulation process. Maximum number of isolates were susceptible to commercially available fungicides viz., Propiconazole, Carbendazim + Mancozeb, Cymoxanil + Mancozeb. Hence we suggest the use of aseptic conditions to control the growth of fungal pathogens in cultivated mushroom not only to overcome the toxic effects of commercially available fungicides but also to prevent the fungal invasion.

For millennia, mushrooms have been valued as edible and medical provisions for humankind. With the popularization of mushroom farming and/or industrialization, mushroom production worldwide continues to increase. It is estimated that more than 10 million metric tons of edible and medicinal mushrooms are produced every year in various countries (Leifa et al., 2006). Mushroom production can convert the huge lignocellulosic waste materials into a wide diversity of products (edible or medicinal food, feed and fertilizers), protecting and regenerating the environment. The oyster mushroom, P. ostreatus is a common edible mushroom. Its cultivation was long confined chiefly in Asia, but it is now cultivated around the world for food. The economic importance of the mushroom lies primarily in its use as food for human consumption. It is rich in vitamin C and B, have most of the mineral salts required by the human body and the niacin content is about ten times higher than any other vegetables. Oyster mushrooms also have good folic acid, alkaline ash and fiber content (Bano and Rajarathnam, 1982). A wide range of diseases can cause serious problems in mushroom cultivation and management of those diseases is a key factor in successful mushroom production. Even though the mushroom itself is a fungus, it can, in turn, be affected by a range of fungal pathogens viz., Aspergillus, Dactylium, Diehlomyces, Fusarium, Mycogone, Papulaspora, Scopulariopsis, Trichoderma, Verticillium, etc., and a variety of bacterial pathogens. Unfortunately, the control of mushroom disease has scarcely been studied. Based on this fact, a study was undertaken to isolate various fungal pathogens of P. ostreatus and its related material from the period of December 2008 to April 2009. The objectives of the present study were(1) Isolation of various fungal pathogens from cultivated P. ostreatus, its mother spawn, run spawn and substrata; and (2) Investigation of the effect of formalin and various commercially available fungicides on the isolates of fungal pathogens.

Biotechnology Journal, Pleurotus Ostreatus, Mushrooms, Mushroom Farming, Lignocellulosic Waste Materials, Oyster Mushrooms, Fungal Pathogens, Mushroom Cultivation Units, Mushroom Cultivation Sites, Chemical Pasteurization, Chemical Fungicides.