6 Wood Discoloration

9.2 Cultivation of Edible Mushrooms 241
leaves and needles from some hardwoods and also from spruce and pine were
used. A short colonization phase of the substrate was done at about 24–28 ◦ C
in closed plastic bags or similar containers. Readiness of the Shii-take to fruiting
became visible in the closed bag, when brown-black wet spots occurred
between the white mycelial mat along the outer surface of the artificial log
and the bag. Then the substrate was a solid block, and the substrate containers
were opened or removed for fruiting at lower temperature of about
12–20 ◦ C. After bag removal, the outer mycelial surface becomes brown and
leathery. Then the logs were sprayed with water once a day, and natural daylight
in a greenhouse was used to stimulate primordia formation. The artificial
light–dark cycle requires light in the 3,700 to 4,200-nm range and intensity
of 400–500 lux (Miller 1998). Several flushes occur within 1 year. After each
cropping, the dry substrate may be re-wetted e.g., by soaking in cold water.
This soaking both replaces the water that has been lost by the growth of
the fruit bodies and the cold stimulates the development of the next primordia.
The yields amounted to about 100% biological efficiency (fungal fresh
weight: dry weight wood; Royse 1985). In Taiwan, for example, 516 companies
produced about 24,000 t of fresh fungi on chopped substrates in 1985,
and a similar quantity was obtained, however, by over 5,000 farmers on wood
sections.
The Shii-take was for a long time the most common mushroom cultivated
on wood worldwide. Altogether, the fungus was the second most frequent
cultivated mushroom with its main production in Japan after the Agaricus
species, which are traditionally cultivated on wheat straw that is composted
with manure or some other nitrogen-rich additive. The Shii-take has been
however overhauled through the increased production of Pleurotus species
particularly in China. Worldwide 526,000 t Shii-take were harvested in 1991
and 1.3 million t in 1997 (Table 9.2). Beside Asia, some Shii-take cultivation
is performed in the USA, Canada, and Europe. In Germany, there is a handful
of commercial Shii-take growers producing some hundreds of tons. A great
part of Chinese and Japanese Shii-take is exported in dry condition to Taiwan,
Singapore, USA, Canada, Australia, and Europe. In Germany, 100 g of dry,
imported Shii-take cost about e10. The local market price varies for outdoorgrown
fungi due to seasonal influences from e10 to 40 per kg fresh weight.
Because of the slow growth of the Shii-take mycelium during the colonization
phase, the cultivation on shopped substrates is endangered by contaminations,
partly leading to parasitism, particularly by Trichoderma species like T. hamatum,
T. harzianum, T. parceramosum,T. pseudokoningii, T. reesei and T. viride
(Albert 2003). Thus, the colonization phase is commonly performed with
pasteurized (60–100 ◦ C) ore autoclaved substrates in plastic bags (Schmidt
1990).
The fundamentals of Shii-take production are known outside of Asia. The
first cultivations in Europe were performed by Mayr (1909) and Liese (1934;
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