First report of Sporobolomyces symmetricus induced red spot disease of Pleurotus eryngii in China.

Pleurotus eryngii is cultivated on a large scale in China and other Asian countries due to its exceptional flavor and its popularity in cuisine. In January of 2009, red spot disease on cultivated P. eryngii was observed in several workshops of mushroom producing factories located at Fangshan District, Beijing, China. Symptoms of this disease began as orange red spots 2 to 4 cm in diam. on the surface of stipes near pilei. The spots did not arise from wounding, and growth of the affected mushrooms halted. Commercial losses for these factories were estimated at 10 to 15%. Samples of diseased tissue were plated on potato dextrose agar (PDA), and dominant colonies were selected for characterization. After 3 days in YM broth (Difco) at 25°C, yeast cells developed that were ellipsoid, botuliform, 4.8 to 7.2 × 2.4 to 3.6 μm, and sediment-formed. After incubation for 1 month on YM agar at 25°C, streak cultures were nacarat, cheese-like, glistening and had a smooth surface and complete margin. On Dalmau plate cult...