Key Points for Autumn Management of Shiitake Mushrooms

Shiitake mushrooms have a long fruiting period, spanning three seasons - autumn, winter, and spring - about 10 months. Generally, inoculation is done in August to September, and fruiting occurs in November to December. Shiitake mushrooms that grow before December are called autumn mushrooms. In shiitake mushroom bag cultivation, autumn management is very important. The key techniques are as follows:

Indoor spawn running. Shiitake mushrooms require more than 60 days from inoculation to physiological maturity. After inoculation, they should be promptly moved into a spawn-running room for cultivation. The bags are arranged in a "#" shape, 8 to 9 layers high, with room temperature controlled at around 25°C and relative humidity required to be below 70%. From 1 to 6 days after inoculation, the mycelium is in the recovery and germination stage, and room temperature should be controlled between 28°C and 30°C. During this period, the bags should not be turned, ventilation should be avoided, and shading should be used to create dim light. From 7 to 10 days, the mycelium begins to grow and colonize the substrate, room temperature is lowered to 26°C to 28°C, ventilation is done 2 to 3 times a day, and on the 7th day the first turning of the stacks is carried out, that is, the stacked bags are moved to swap upper and lower, inner and outer positions, so that every bag can receive management under the same conditions. When turning the stacks, handle them gently to strictly prevent damage to the seals and contamination by foreign fungi, and at the same time carefully check for contamination during turning. If pinpoint contamination is found, inject a mixture of 50 ml of 75% alcohol and 30 ml of 25% formaldehyde to seal the affected area. If contamination appears on the inoculation block or around it, dig out the contaminated part and re-inoculate. If contamination is on the sealing material, spot-apply 0.2% potassium permanganate or carbendazim to the affected area. After 11 to 15 days, the mycelium grows vigorously and has expanded to 4 to 6 cm. Room temperature should be maintained at 24°C, ventilation should be increased, and the second turning of the stacks should be carried out. One day later, use a bamboo needle to punch holes to increase oxygen, piercing 4 slanted holes around the expanding mycelium. Bag temperature should be controlled at 20°C to 24°C and must not exceed 26°C. After 50 days, remove the shading material from doors and windows to promote mature and robust mycelial growth.

Bag color change. The timing and quality of color change affect both the timing of fruiting and the yield. After the mycelium reaches physiological maturity, it changes from white to reddish-brown, and yellow water droplets appear, followed by the emergence of shiitake primordia. During the color-change period, increase diffused light indoors, strengthen ventilation, and open and cover the plastic film intermittently to create an alternately dry and moist environment that promotes color change.

Outdoor fruiting induction. Shiitake mushrooms are a low-temperature, temperature-variable fruiting type. After the bags have changed color to form a reddish-brown mycelial film, move the bags to a shaded outdoor area, cover them above and below with wheat straw mats, and sprinkle water to retain moisture. Cover with film at night and uncover during the day, repeating for 4 to 5 days, then cover with plastic film to induce fruiting by keeping the mushrooms enclosed.

Fruiting management. In autumn, temperatures gradually decline, which is beneficial for robust mycelial growth. Three days after fruiting induction, pick out the fruiting bags once a day and place them on the bed frames in the mushroom shed, with a bag spacing of 7 to 10 cm, until fruiting induction is completely finished. After the bags are placed on the bed frames, use a sharp knife to cut the film around the mushroom buds to carry out bud restraining. Generally, during the 7 to 10 day bud-restraining period, do not cover with film. When the young mushrooms reach the size of peanut kernels, flower induction can be carried out.

Management during the flower induction period. 1. Humidity. Maintain relative humidity inside the bags at 80% to 90%, keep the temperature at 12°C to 18°C, and provide relatively abundant diffused light and good ventilation. If humidity is too high, first drain moisture, then uncover the film for 1 hour and cover it again, and open 1 stove to remove dampness. If it is dry, place a pot on the stove and add water, and cover with plastic film to raise the shed temperature to 28°C. If the shed film drips and the young mushrooms become damp, open the doors and windows and open 1 stove to remove moisture. 2. Temperature. Because shiitake mushrooms have the characteristic of fruiting under variable temperature, artificially widening the temperature difference and alternating dry and wet conditions can force the caps to crack and form flower mushrooms. Therefore, cover the film during the day to let sunlight through and raise the mushroom shed temperature to 28°C, then after 12 midnight open the film to let cold air in, so the day-night temperature difference can reach more than 10°C. For 3 to 4 consecutive days, this can stimulate the emergence of large numbers of mushroom buds. 3. Alternating dry and wet. After variable-temperature induction of buds, when the fruiting bodies grow to 2 to 3 cm, choose a sunny midday to splash water on the ground surface to accelerate fruiting body growth, then uncover the film at night to let cold air stimulate them and dry the caps, then cover the film again, using ground warmth and ground moisture together with alternating dry and wet conditions to promote the caps to split into patterned flower mushrooms.