Textbook of Field Practices in Bioresource Production, University of Tsukuba Forestry (1) Inoculation of mushrooms 1. Mushrooms as minor forest products According to the definition by the Forestry Agency of Japan, minor forest products are defined as “products produced mainly in forests or wilderness areas and are a generic term for forestry products (including processed charcoals) excluding general timbers.” Specifically, minor forest products include mushrooms, fruits of treees, wild plants, bamboos, and charcoals. Because a timber-production cycle is necessary to a long period often up to several decades, minor forest products are important income sources for forestry, particularly family-based forestry businesses. In recent years, minor forest products have accounted for about half of the total forestry production in Japan. The most of the minor forest products in Japan are mushrooms. Amount of mushroom production is increasing. The national production of mushrooms was 456,000 t and the output was 212.9 billion yen (about 80 % of the total output of all minor forest products) in 2012. Enoki (Flammulina velutipes), Buna-shimeji (Hypsizygus marmoreus), Shiitake (Lentinula edodes), Maitake (Grifola frondosa), king oyster mushroom (Pleurotus eryngii), and Nameko (Pholiota microspora) are major mushroom productions. Although some mushrooms that grow naturally are harvested at managed forests such as Matsutake (Tricholoma matsutake), the most of the commercial mushrooms are cultivated artificially. Many varieties have been developed for each mushroom type. 2. Procedure of mushroom cultivation Artificial mushroom cultivation can be divided into log cultivation, in which spawns are directly inoculated into a log (nurse tree), and solid media cultivation, in which spawns are inoculated into sawdust or rice bran. There are different log cultivation methods; for example, Shiitake cultivation uses a log (1 m long each), while the cultivation of Maitake mushrooms, which have low resistance to bacteria, uses short, heat-sterilized log pieces (15–20 cm) (sterilized log cultivation). In this practice, you will learn how to grow Shiitake, oyster mushrooms (Pleurotus ostreatus), and nameko using log cultivation. You will inoculate spawns in the spring semester and harvest grown mushrooms in the autumn semester. 1) Logging of nurse trees Mushroom species are characterized as specific relation to their nurse trees. For example, suited to different tree species, and deciduous broad-leaved trees such as Mizunara oak (Quercus crispula), Konara oak (Quercus serrata), beech (Fagus crenata), Kunugi oak (Quercus acutissima), hornbeams, maples, and cherry trees are popular nurse trees in mushroom cultivation. These trees are logged in advance, and dried with branches and Seishi Kadowaki, Tatsuyuki Seino and Masahiro Fujioka, AFRC, University of Tsukuba 1 Textbook of Field Practices in Bioresource Production, University of Tsukuba leaves, leaving them intact. The duration and extent of wood drying vary by tree or mushroom species, but the duration is normally a few months for shiitake cultivations. For this practice, we will use logs that already harvested by technical staff of the Tsukuba Experimental Forest and/or Yatsugatake Forests, and so on. 2) Cross cutting Partly dried logs are cut into appropriate lengths. This cutting may be done immediately after logging. Lengths are determined with consideration for ease of handling, ease for spawns to spread, and harvest years assumed, among other factors. The length should be around 1 m for shiitake cultivations. If you are doing short-log cultivations, the length should be around 15 cm. Cut pieces are dried in the shade avoiding direct sunlight. In some cases, spawns are inoculated immediately after cutting. In this practice, logs have been already cut to suitable lengths by a chainsaw. You will inoculate into the logs prepared in advance. 3) Inoculation This is the main part of this practice. You will have to drill holes in the logs using a special drill or a borer and pound spawn pieces into the holes using a hammer. Spawn pieces are sawdust or wood pieces shaped into wedge forms (8.5 mm in diameter × 18 mm in length), in which mushroom spawns are grown. You need to hit a spawn piece into a bed log such the top of the piece is flush with the log’s surface. This will leave some space in the bottom of the holes (see figure). The special drill is efficient and can make nice, round holes, but you need to hold the drill tight and concentrate on the drilling work. Use of a borer, if done by an inexperienced person, may result in shallow holes or holes in inappropriate positions, and also requires physical strength and time; however, the borer is inexpensive and has the advantage of not requiring a power source. For shiitake cultivation, holes should be drilled in the intervals of 20–30 cm vertically and 5–8 cm horizontally. On short pieces of wood, holes are positioned at equal intervals on cut sections. Seishi Kadowaki, Tatsuyuki Seino and Masahiro Fujioka, AFRC, University of Tsukuba 2 Textbook of Field Practices in Bioresource Production, University of Tsukuba Drilling on a nurse tree (for Shiitake) Vertical: 20–30-cm interval each Spawn piece Horizontal: 5–8-cm interval each Do not hit pieces too Bed log surface deeply or leave the spawn piece protruding. Drilled hole Inoculation in short log cultivation (for oyster mushrooms and Enoki) Outer circle on section: Diameter/2 = 8 pieces Inner circle on section: Outer pieces/2 = 4 pieces Circumference: Diameter/2 = 8 pieces Holes are made on the cut section and Height 15 cm the circumference. Spawn pieces are inserted and two bed logs are the cut Diameter 15 cm sections facing each other. 4) Preliminary storage The nurse trees are stored in a place at first protected from direct sunlight and rain that has good drainage and ventilation so that the inoculated spawns become firmly rooted in the logs. The method and timing of log placement are determined by mushroom species and log size. The logs are watered as necessary. 5) Main preparatory storage The best environment for mushroom spawns is not necessarily the same as that for mushroom growth. The main preparatory storage involves relocating nurse logs to promote mushroom growth. This is done by the technical staff as necessary. Seishi Kadowaki, Tatsuyuki Seino and Masahiro Fujioka, AFRC, University of Tsukuba 3 .