The "natural log" method of growing shiitake is still practiced by most of the Orient's shiitake farmers. However, in the West, where shiitake farming is relatively new, the high-tech method of growing shiitake indoors under controlled conditions on "synthetic sawdust logs" (actually sawdust blocks) is used by approximately 80 percent of the large commercial growers.
The method of growing shiitake on sawdust logs is a direct outcome of the biotechnical revolution that has taken place since World War II. Drawing on the latest technology, exotic mushroom cultivators mix various nutrients into sawdust, which is then formed into a block, sterilized, and inoculated with shiitake mycelium. The blocks are then placed in semi-sterile growing rooms under "ideal conditions" to maximize mushroom growth.
Ideal growing conditions usually create an opportunity for other fungi to grow and compete with the shiitake on the synthetic logs. As a result, most high tech cultivators are forced to spray their growing rooms with fungicides.
The controversy over which method of cultivation produces the most delicious and nutritious mushrooms is a heated debate in the exclusive world of exotic mushrooms. Mitoku shiitake grower Fusataro Taniguchi and other traditional shiitake growers feel that shiitake grown on synthetic sawdust logs look and taste inferior to their natural log-grown mushrooms. In addition, they believe that the fungicides used to control pests in the semi-sterile growing rooms pose a health threat to consumers and workers.
By looking at the life cycle of shiitake, it is possible to understand which set of growing conditions will enhance its medicinal properties. Mushrooms sit close to the lowest rung in the ecosystem, thriving on decaying materials in a very hostile environment. During the growing stage shiitake send out thin hairs called mycelia that secrete powerful enzymes to digest food outside the cell. Since the mushroom needs to absorb the digested food, it must first deactivate any natural pathogens by utilizing its unique polysaccharide peptide properties. Mushrooms are also very proficient at expelling undesirable chemicals and contaminants that are absorbed during ingestion. Therefore, in order for shiitake and other mushrooms to compete and thrive, their very existence depends on their biologically unique, aggressive, and adaptive immune system. Therefore, shiitake grown outdoors, subject to the rigors of the natural wild environment, should have more concentrated medicinal properties than shiitake that are protected and pampered in growing rooms.