Introduction

China is the world's major mushroom producing country. Agaricus production is mainly for export but Lentinula edodes (shiitake or shiang-gu) is the traditional local product, and now the major crop. Lentinula edodes is indigenous to China. It was first cultivated there more than 800 years ago, and today, China accounts for about 70% of world production. In 1997, Chinese production was recorded as 91 500 metric tonnes of the dried crop (drying produces the characteristic taste of the mushroom), ten times that in fresh weight. Shiang-gu (the Chinese name) is presently about the second or third most popular cultivated mushroom in the world, being consumed throughout China, Taiwan, Japan and Korea, and with increasing world-wide popularity. One-third of the Chinese crop is exported. As this amounts to the equivalent of about 300 000 tonnes of fresh mushrooms, the industry is an important earner of foreign exchange as well as making a very significant contribution to the income of peasant-farmers especially of the mountainous regions in China (Chang & Chiu, 1992). In these regions the land is poor in fertility and too distant from reliable transport to make conventional farming of green crops profitable.

Traditional technology

The traditional log-pile cultivation method is still the one that is most frequently used. For this, locally felled logs (oak, chestnut, hornbeam, maple and other trees) over 10 cm diameter (probably about 20 to 30 years old) and 1.5 m to 2 m long are normally cut in spring or autumn of each year.