Key Management Techniques for Spring Mushrooms in Bag-Cultivated Shiitake (Lentinula edodes)

Spring management of shiitake mushrooms must be tailored to local climate conditions. The spring climate in Jiangnan is characterized by low temperatures, overcast and rainy weather, and high humidity. Once the daily average temperature exceeds 12°C, spring mushroom management can begin. Spring is the peak season for outdoor shiitake production, accounting for 30%-60% of the annual shiitake yield (depending on the variety and how early or late the substrate logs were made). Before management begins, water supplementation should be carried out separately according to the number of fruiting flushes, the degree of water loss, and contamination conditions.

(1) Water supplementation: After 2-3 harvest flushes in autumn, the water content of the substrate logs gradually decreases as the number of fruiting bodies increases, the management period lengthens, and the sawdust decomposes and nutrients are consumed. By early spring, the water content of the substrate logs is only 30%-35%, and the mycelium is in a semi-dormant state. Therefore, water supplementation is essential to meet the moisture demands for primordium formation. When the spring temperature stabilizes above 10°C, water supplementation can begin. The method is as follows: First, lay plastic film in the trench. Use No. 8 iron wire or sharpened steel bars 6.5 mm in diameter to puncture holes in the cross-section at the ends of the substrate logs, with a hole depth of 25-35 cm. For logs with severe water loss, puncture two holes (without puncturing, the water absorption rate of the logs will be affected). Then, place the punctured logs parallel to the water trench in 3-4 layers. Lay another layer of waterproof plastic film over the logs, forming a pool or cylinder shape. First, add water to the upper film to a depth of 25-35 cm, using the weight of the water itself to evenly compress the logs inside, then add water to soak the lower logs. No additional weighting or fixing on top is needed, and the logs will be fully submerged in water. If the logs float to the surface after soaking, even water absorption cannot be achieved. For the first soaking of logs for water supplementation in early spring, because the logs have lost too much water, the soaking time should be controlled at 8-12 hours. After each soaking, drain all water from the trench, allow the free surface water on the logs to air-dry, then carefully move them back to the mushroom beds for routine management. Recently, in some areas of Fujian, to save labor on moving logs, electricity has been brought into the mushroom sheds, with electrical outlets set up at various points, and small self-priming (centrifugal) electric pumps used to draw water from one end into the soaking trench while the other end is connected to a sprinkler head. Although the one-time investment is relatively high, it saves a great deal of labor and management costs.

(2) Fruiting: In response to the characteristics of continuous spring rain and high relative air humidity, after the substrate logs have been replenished with water and placed on the racks, the shade material on the canopy should be thinned out to increase the temperature and sunlight inside the shed, enlarge the day-night temperature difference, and induce primordium formation. Spring air pressure is relatively low. To meet the oxygen demands of shiitake development, the bamboo strips arching over the bed racks can be raised by 0.3 m, and on rainy days the film covering can even be fully opened to enhance ventilation. After the Awakening of Insects (Jingzhe) solar term, thunderstorms become frequent, and excessive water drenching of the fruiting bodies must be prevented, as it makes drying difficult. When covering with film, ensure ventilation on the sides or at both ends; do not cover too tightly, and open it immediately after the weather clears. Late-maturing varieties produce large amounts of shiitake after the beginning of spring, with March to April entering the peak fruiting period. After each harvest flush is completed, allow the mycelium to recover for 7-10 days, then repeat the above methods of water supplementation, primordium induction, and fruiting, cycling continuously. Late spring temperatures fluctuate considerably, so the focus should be on preventing high temperatures and high humidity, with cooling measures as the priority. The canopy shade can be thickened, and the surrounding shade curtains thinned out. Mushroom yards at low altitudes end spring shiitake management in late April or early May (depending on local temperatures). After clearing the yard, they switch to cultivating other edible fungi such as Auricularia cornea (wood ear), allowing the mushroom shed to be used year-round. In high-altitude mountainous areas, shiitake cultivation strains often continue until June, but yields in the later period are very low due to severe shrinkage of the substrate logs.