LAUSR

Lentinula edodes, known as shiitake, is the main cultivated edible mushroom worldwide, representing about 22% of the world’s output, with China being the major producer. In 2017 symptoms of cobweb were observed on cultivated shiitake mushrooms in Castilla-La Mancha (Spain), affecting more than 30% of the blocks of pasteurized substrate. Cobweb appeared at the end of the crop cycle as circular white patches over the surface of the blocks of substrate and fruitbodies. The fine grey-white mycelium rapidly covered pinheads, stalks, pileus and gills, eventually resulting in the decomposition of the entire fruitbody. The mycelium can colonize the surface of the substrate completely and may turn reddish brown. To isolate the parasitic fungus, infected tissues of L. edodes were plated onto potato dextrose agar (PDA). Fungal colonies consisted of white, cottony, aerial mycelium that spread rapidly on the PDA, changing from white to yellow and finally, pink, as the red pigment spread into the agar. The conidiogenou...