Abstract

In the cultivation of oyster mushroom (Pleurotus spp), various contaminants moulds such as Trichoderma spp that are often found in production plants, leading to losses exceeding 77% in a short periods of production were identified. This research studied the effect of pH on two solid cultivation mediums, potato dextrose agar (PDA) and yeast complete medium (YCM), evaluating mycelial growth and the rate of development of strains of Trichoderma viride and Pleurotus ostreatus. The pH levels studied were 7, 9 and 11 approximately which were obtained with sodium hydroxide (NaOH-1N), Ca(OH)₂ and CaS0₄ (lime and gypsum commercial); the control group has a pH of 5.7 according to the manufacturer. The strain of P. ostreatus (CP-50) obtains a development rate of 6.10 mm / day at pH 11.2 presenting tolerance at alkaline pH; however, the strain of T. viride (CP-T4) has a rate of development of 0.41 mm / day at pH 11.2 showing negative effects on growth and development in alkaline pH.

Key words: Trichoderma spp., Pleurotus spp., pH, development rate, mycelial growth.