Mushrooms
Their Consumption, Production and Culture Development

Assistant Professor Daniel J. Royse and Professor Lee C. Schisler
Department of Plant Pathology, Pennsylvania State Universitry,
University Park, Pennsylvania

To understand spawn, spawning and spawn growth, the mushroom itself must be understood. Mushrooms are fruits of the fungus plant and consist of two main parts, the cap and the stem. As the mushroom matures the cap opens and the gills are exposed. Mushroom spores are produced in the gills. Spores are microscopic spheres roughly comparable with the seeds of higher plants. These spores are produced in large numbers in the gills. A 7.5cm. mushroom produces as many as 40 million spores an hour. Since spores germinate and grows into mycelium rather than unpredictably, they are not used to seed mushroom compost. Spores will germinate and grow into a thread-like mycelium, which a laboratory producing spawn uses. Mycelium from the spores is placed onto steam-sterilized grain fully grown through by the mycelium is spawn, and spawn is used to seed mushroom compost.

Spawn was first obtained by digging up wild mycelium from meadows where wild agarics grew and horses were active. The early methods of finding, digging up perpetuating the wild mycelium were uncertain and unreliable. The first manufactured spawn combined a mixture of horse and cow manure pressed into bricks, the original source being the wild mycelium. The bricks were not sterilized, however, and could harbor pathogens and weed molds.

In 1915 pure culture spawn was produced on sterilized horse manure compost in bottles. The development of horse manure spawn, however, did not eliminate the problem of obtaining productive, reliable spawn, free from pests. In 1930, The Pennsylvania State College (University) employed Dr. James W. Sinden to work on mushroom production problems. During one his first series of experiments Dr. Sinden was struck with the variation in yields and feared that this might be a result of spawn planted. He realized that in order to carry on further experimental work on mushroom growing, it was essential to eliminate any variation from this cause. Therefore, Dr. Sinden sought a medium on which the mycelium would grow more vigorously and that would provide a more uniform product. One of the first of these used was grain, specifically wheat, which was placed in flasks with a small amount of water and heat sterilized. On introduction of the mycelium he found that it grew very vigorously and in a manner entirely different than anything previously seen. Thus grain spawn was born and Is used almost exclusively today.

• Interdisciplinary Science Reviews, Vol 5, No. 4, 1980