The basic principles and practices of the cultivation of shiitake mushroom (Lentinus edodes (Berk.) Sing.) on tree logs under forest conditions at Beltsville, Maryland, are described. Spawned logs were supported to prevent contact with the soil, but no additional cultural practices were used to promote mycelial growth or mushroom fruiting. The best and most consistent mushroom yield was obtained from black and white oak. The total yield from oak logs about 90 g fresh weight mushrooms/kg fresh weight (FW) log (5 year crop cycle), was about 50% ofthat reported for large scale commercial production of shiitake mushrooms in Japan. Results of these experiments indicate also that there does not appear to be any substrate barrier to the escape and naturalization of L. edodes in the northeastern United States.
Compost spawned with the cultivated mushroom, Agaricus bisporus (Lange) Sing. ‘White’, was cased 7-42 days after spawning. Uncased spawned compost was stored by covering it with polyethylene plastic film. Results indicated that the earlier the beds were cased, the earlier the fruit appeared. The earliest crops tended to yield less than later crops. A 10 to 14-day spawn growth period before casing was optimum. A potential use of plastic film to regulate crop production is discussed.
The world’s total production of cultivated fleshy fungi is estimated to be about 6 × 108 kg/year. Approximately 75% of this production is of one species, the so-called cultivated mushroom or champignon, Agaricus bisporus. Shiitake, Lentinus edodes (Berk.) Sing., is second in importance with about 20% or 1.2 × 108 kg. Included in the remaining production of 2.5 × 107 kg are species of Volvariella (Paddy straw mushroom), Pleurotus (oyster mushroom), Tuber, (truffles), Auricularia (ear fungus), and Tremella (jelly fungus) (16, 40, 46). Flammulina velutipes (Fr.) Sing. (winter mushroom) also is cultivated commercially. About 1/4 of the world’s production of Agaricus bisporus, 1.3 × 108 kg, was produced in the U.S. in 1974. Present farm value of the U.S. mushroom crop is about $123 million. Today, especially in Europe and Asia there is considerable interest in commercial production of cultivated mushrooms other than A. bisporus.
Serial dilution of basidiospores of a spore print to prepare grain spawn of the Oyster mushroom is described. The method, which has a contamination rate of about 5%, requires sterilization of a grain medium and the use of some simple “clean” procedures. The method is especially advantageous for small scale and part-time cultivation of mushrooms on logs. Pleurotus ostreatus Kumm. mycelium grew rapidly into the wood of freshly cut logs inoculated with disks of grain spawn prepared using spore inoculum. Unlike pure-culture spawn disks, however, disks prepared from spore-inoculated grain did not become completely tightly bonded to the wood surface.
Stock cultures of the cultivated mushroom in the form of rye grain spawn were preserved at −160 to −196 C for periods up to a year. Mycelial growth of the cultures was about the same after storage as before. A total of 285 spawn cultures derived from 66 different vials of preserved material, without exception, grew normally on rye grain and compost. Spawn performance of two strains each of White, Intermediate, and Brown mushroom varieties was evaluated after 2, 70, and 180 days storage. Results of yield tests indicated that there was no significant difference, in quality or quantity of mushrooms produced, between any preserved spawn and its check. The effect of glycerol or dimethyl sulfoxide as a protective agent during freezing was determined. Though the presence of a protective additive did not appear essential for short storage times, glycerol was added routinely in all later tests. Results to date indicate that the storage method potentially has great value for mushroom research and spawnmaking.