Key Management Techniques for Autumn Mushrooms in Shiitake Log Cultivation

After the stages of temporary bed-log piling and bed-log piling, the mycelium inside the logs has fully spread, and at this point the logs are renamed mushroom logs. Judging whether the logs have developed into mature mushroom logs is a fairly critical step. The characteristics of mature mushroom logs are: the logs gradually decay, become soft and loose, become lighter, and gain more than 20% in weight after absorbing water; the bark is no longer smooth, showing small bumps, with rice-grain-sized white spots that are the rudiments of shiitake primordia formation. If the small bumps are not obvious, you can judge by touching with your hand; if pressing with a finger feels soft and elastic; tapping the mushroom log produces a low, dull sound rather than a crisp one, indicating the mushroom log has matured. Judging the maturity of mushroom logs is not easy and requires long-term practice to master. Mature mushroom logs will be moved into the mushroom yard for fruiting management.

(1) Selection of cultivation site Currently there are two forms of shiitake cultivation sites. One is to select the cultivation site directly in coniferous or broadleaf forest with a shade level of more than 70%, choosing a relatively flat slope on the hillside of an east, south or southeast slope (a sunny slope with a large day-night temperature difference, which favors temperature-varied fruiting), close to a water source with a certain drop in elevation (for sprinkler irrigation to combat drought), well-drained and ventilated as the mushroom yard. Clear away small shrubs and weeds in the mushroom yard, set up a windbreak wall at the mountain wind gap, and clear away ant nests to prevent ants from boring into and eating the mushroom logs. The other is an artificially built shade shed that imitates a forest environment, placing the mushroom logs inside the shade shed.

(2) Laying down the logs Carefully move the mushroom logs from the piling site into the cultivation yard, taking care never to damage the bark. After several months of piling management, the mushroom logs have lost a great deal of water. To replenish the moisture in the mushroom logs, after moving them into the mushroom yard, lay the mushroom logs down and let them fully absorb moisture, and be sure to turn them. For softwood tree species planted that year and small-diameter mushroom logs with relatively high maturity, they can be gathered and laid down for a continuous week of sprinkling with turning, so that they absorb moisture evenly and accumulate enough water for the formation of fruiting body primordia. For hardwood tree species, large- and medium-diameter logs, and logs planted that year with poor maturity, after turning the pile continue piling in place or lay the logs down, let rain and snow soak and press them, and rely on ground temperature to keep them warm through the winter, preventing water loss, and enter spring management the following year.

(3) Soaking For mushroom logs that have lost too much water, the soaking method must be used to let the mushroom logs absorb enough water, providing enough moisture for shiitake development. At the same time, give the mushroom logs a temperature difference stimulus (difference between water temperature and air temperature) and a dry-wet difference stimulus to induce shiitake primordia to burst out. By controlling the length of soaking time, some weak primordia are drowned, thereby achieving the purpose of "fruit thinning" and favoring the cultivation of high-quality mushrooms. Mushroom logs suitable for soaking must be mature or logs after the previous batch has been picked; the latter must undergo "rest and recuperation." Soaking facilities include underground, semi-underground and mobile water tanks. The length of soaking time has a certain relationship with the maturity (decay) of the mushroom logs, the temperature difference between air temperature and water temperature, tree species, and cultivated strain, and is especially closely related to the first two. For small-diameter, thin-barked tree species planted that year with mature mushroom logs, soak for 36 hours; the next year soak for 24 hours; the third year for 12 hours. This is mainly because as decay increases, the mushroom logs become more likely to absorb moisture. The soaking time for large-diameter, thick-barked mature mushroom logs is correspondingly extended by 12 hours. When the temperature difference between the water and the inside of the mushroom log is large, the mushroom log absorbs water quickly; when the temperature difference between the two is small, the mushroom log absorbs water slowly. When soaking, also consider the variety cultivated on the mushroom logs to be soaked. After soaking, high-temperature varieties placed at medium temperature still do not fruit; this is mainly because the temperature required for the differentiation of high-temperature varieties cannot be met. After soaking, scoop them out and stack them in a "#" shape or in another way; the stacking method can be determined by the dry-wet degree of the site, and let them drain. According to the variety, the degree of water absorption of the mushroom logs, and meteorological conditions, use or do not use plastic film covering (depending on the site's heat and moisture retention conditions), generally controlled at 15-18°C, and after 2-5 days "bud bursting" can be seen successively. Some beginners are eager for mushrooms and, for large-diameter hardwood tree species planted that year whose mycelium has not yet fully spread to form mushroom logs, use the soaking method in autumn and winter to stimulate fruiting, but instead outsmart themselves and produce only a small number of scattered small mushrooms. Some people, after soaking, scoop out the mushroom logs and tap them a few times on a stone block, calling this "shocking the mushroom." This practice can sometimes form a large number of mushroom buds, but when there are too many buds, the nutrient supply is dispersed, forming inferior mushrooms or even tiny mushroom buttons; in addition, it seriously damages the mushroom logs and affects the next batch of fruiting.

(4) Raising the racks When the burst-out mushroom buds are the size of a little finger, you can prepare to raise the racks. Before raising the racks, a "screen" must be set up at the mountain wind gap to increase the humidity of the fruiting site. Drive a pair of wooden stakes into the cultivation yard, use barbed wire pulled tight as the "crossbar" (to prevent the mushroom logs from sliding after the racks are raised), and arrange the mushroom logs in a herringbone (palms-together) pattern crossing over the "crossbar." Determine the inclination of the mushroom logs on the crossbar according to the shade level of the cultivation site, the degree of slope, and the water-holding capacity of the soil; sites with better moisture retention can be set steeper, otherwise set them more slanted. Where humidity is low, the mushroom logs should be kept close to the ground to maintain the moisture in the logs so that they can fruit smoothly. In addition, leave spacing between the mushroom logs, with 10-16 logs per sq m; leave certain walkways between racks for entering and leaving to pick mushrooms.

(5) Management after raising the racks Autumn and winter climates are relatively dry, so the relative humidity of the mushroom yard space (75%-85%) must be effectively controlled, alternating dry and wet, to favor the compactness of the mushroom body tissues. For this purpose, artificial misting can be used (do not sprinkle water directly onto the caps, otherwise the caps easily turn black and rot); the finer the mist droplets, the better, floating and falling freely, to obtain higher-quality shiitake. After raising the racks, be sure to pay attention to ventilation in the mushroom yard, otherwise it easily causes miscellaneous bacteria to breed. Shiitake is an aerobic fungus; if it is too stuffy and humid, it easily causes the mushroom stipe to become fat and the cap to be rather small or even the mushrooms to rot, so small shrubs and weeds under the forest in the cultivation yard must be cleared. In small mountain hollows with dense shade, if necessary, appropriately thin the lower half of the branches of the shade trees to favor ventilation in the mushroom yard. In early autumn, guard against frost, especially in mushroom yards with less shade. The length of fruiting body development time in autumn and winter is related to the strain and also depends on air temperature and relative humidity of the space, generally ranging from 15-20 days. Under conditions of low temperature and low relative humidity (75%-85%), the thick mushrooms and flower mushrooms formed are deep in color and rich in aroma, with extremely high commercial value. After harvesting, the mushroom logs are still laid down to absorb moisture and keep warm through the winter, and management is carried out again in the following spring.