Biological efficiency is a ratio of the fresh weight of mushrooms harvested to the initial weight of ovendry substrate, expressed as a percentage. For example, if a substrate log weighs 20 kilograms (about 40 pounds) at spawning and has a moisture content of 50 percent, the oven-dry weight would be 10 kilograms (about 20 pounds). If a total of 2.5 kilograms (about 5 pounds) of mushrooms are harvested during the lifetime of the log, the biological efficiency would be 25 percent for that log.

Bioremediation is the use of biological agents, such as bacteria or plants, to remove or neutralize contaminants in polluted soil or water.

Browning is the oxidation of surface mycelium, also called “artificial bark formation” or “curing” by growers.

Flush is a term that describes one crop or break of mushrooms. Flushes occur three to five times per year on natural logs and every 16 to 20 days on synthetic logs.

Inoculation, or Spawning, is the process of introducing the spawn into the substrate.

Mycelium is a fine, hairlike structure or tissue. It is not unlike the roots of a higher plant. Shiitake mycelium, when cultivated, spreads and colonizes its substrate, eventually producing “fruit,” or mushrooms.

Spawn is the term used to describe the vegetative growth or pure culture mycelium on a suitable sterilized substrate, such as wood chips or wood plugs. The spawn in this form is introduced to a larger, prepared substrate such as a natural or synthetic log. The mycelium grows out from its plug, wood chips, or cereal grain and colonizes the new tissue, eventually producing its “fruit,” or mushrooms.

Substrate is the medium that mycelium bores through and grows within. In mushroom production, the substrate for the mycelium is initially wood chips, wood plugs, or cereal grain, but is later either a natural or a synthetic log.