How to prevent and control excessive browning of shiitake mushroom logs that results in no fruiting

1. Causes of the problem. Log browning is a physiological process in the development of shiitake mushroom mycelium and is also a sign of physiological maturity of the mycelium. Suitable conditions for log browning: temperature of 18°C to 24°C, air humidity of 80% to 85%, some scattered light, and good ventilation. If the indoor temperature exceeds 25°C during browning and this high temperature lasts for a long time, it can cause the logs to secrete large amounts of yellow water and pigments, thereby forming a thick brown mycelial skin. The thick mycelial skin formed can block air, causing the mycelium to receive no oxygen and be unable to fruit.

2. Prevention and control measures. (1) Tapping method. When the logs have matured and the fruiting season has arrived, find a stone about the size of an egg or a wooden stick and tap evenly from one end of the log to the other, with the tapping points arranged in two rows. For cluster-forming varieties, tap 6 points; for single-fruiting varieties, tap 8 points. After tapping, place the logs in the mushroom shed. The mycelial skin of the tapped logs develops cracks from the vibration and pressure, allowing air to circulate inside the log, and the internal mycelium is stimulated to speed up knotting and form primordia. The tapped logs fruit neatly, with no deformed mushrooms. (2) Piercing method. Use a steel wire 6 to 8 mm in diameter to pierce 3 holes at each end of the log, and pierce one vertical hole in the middle of the log; the holes must go all the way through. After piercing, tap the logs again, then place them in cold water to soak for fruiting. (3) Fumigation method. Gather the logs with thick mycelial skin into one mushroom shed. When the nighttime temperature drops to 15°C, cover the shed film tightly, place two charcoal fire basins in the shed 4 m apart, and pour diesel into the basins so that the diesel burns fully. At around 10 o'clock the next day, after the temperature rises, open the shed film for ventilation. This method can soften the mycelial skin and allow smooth fruiting. (4) Sunlight and heat preservation method to promote primordia. If the temperature is too low at fruiting time and does not meet the fruiting requirements, first pile the logs outdoors in a sunny place and cover them with plastic film, using light to raise the temperature. When the temperature of the log pile rises to 20°C, soak the logs in cold water so that they absorb water and reach the suitable water content, then take them out and air-dry the surface moisture of the logs, then pile the logs up again and cover them well with plastic film, drawing in light and preserving moisture to promote primordia for 5 to 8 days; mushroom primordia can then form quickly. This method works better for logs with thick mycelial skin and a dry mycelial skin surface.