What are the methods to prevent deformed and mutated shiitake mushrooms?

During the growth of shiitake mushroom fruiting bodies, "candle mushrooms" often appear, with a hole that has a stem but no cap, as well as "pinecone mushrooms" and "lychee mushrooms." These are all deformed and mutated shiitake mushrooms, most of which belong to physiological diseases.

Besides inferior spawn or viral infection, the main human-related causes of deformed mushrooms are: (1) Improper variety selection. For example, mountainous areas with high altitude should choose medium- and low-temperature-type spawn; if high-temperature-type spawn is mistakenly used, the mushroom buds will shrink and stop growing when they encounter low temperatures in winter, forming "pinecone mushrooms." (2) Improper development management. For example, if mushroom buds appear early inside the bag, they cannot stretch normally due to compression from the bag wall, and the first generation of mushrooms is prone to deformity. (3) Bag removal and color change do not meet the standard. (4) Soaking the mushroom logs is inappropriate. For early-maturing varieties, after generally 2-3 flushes of mushrooms, the moisture in the mushroom logs begins to decline, so they should be soaked in time to replenish liquid. However, some mushroom growers cultivate late-maturing varieties and also soak them. Because late-maturing varieties are in the stage of forming primordia, stimulation by water forces the primordia to differentiate prematurely, producing only stems and thus becoming "candle mushrooms." (5) Humidity control and heat preservation are unreasonable. In winter, when temperatures are low and the plastic film covering the mushroom bed is not laid flat, mushroom buds that are growing will shrink, dry up, or mutate when attacked by cold wind. When the relative humidity is less than 70%, soft or hollow mushroom stems may also appear.

Prevention methods: (1) Understand the characteristics of the mushroom and prevent mistakes in introducing spawn. Before cultivation, first clarify the characteristics of the spawn, select suitable varieties according to local conditions, arrange the inoculation season accordingly, and calculate the scheduled inoculation time. (2) Understand the maturation characteristics of the mycelium and prevent blind bag removal. If the bags are removed too early and the mycelium has not reached physiological maturity, there will be more deformed mushrooms. To judge whether the mycelium is physiologically mature, master "one mycelial age and three standards." "One mycelial age" means about 60 days from the date of inoculation. "Three standards" means that the nodular protruding bubble-like mycelium in the bag accounts for 2/3 of the entire bag surface, brownish color appears locally, and the mushroom bag feels soft and elastic when held. (3) Master the color-change pattern and prevent temperature from getting out of control. During the color-change period, pay attention to temperature changes. For the first 3 days, the temperature should be controlled within 25°C, and the film covering the mushroom bed soil does not need to be uncovered for ventilation. Under normal conditions, color change ends in 12 days, and the first flush of mushrooms appears after 3 days. The temperature during color change must not be lower than 12°C or higher than 25°C. The optimal temperature for fruiting is 15°C. (4) Master the principle of temperature variation and prevent insufficient temperature difference stimulation. During the day, cover the mushroom bed with plastic film, and after 12 at night, uncover the film for 1 hour, so that the day-night temperature difference is above 10°C. (5) Soak in water timely and in appropriate amount to prevent the water moisture from being too early or too low. When the water content of the mushroom logs is less than 40%, fruiting is difficult and there are many small mushrooms. Generally, soak when the weight of the mushroom logs has decreased by 30% compared with the original, and it is appropriate to reach 95% of the weight when the bags were made after water absorption. If the water absorption is too full, it is easy to cause difficulty in mycelial respiration and affect normal mushroom growth. (6) The method of promoting mushrooms should be appropriate to prevent being too dry or too wet. After each batch of mushrooms is harvested, the film must be uncovered for ventilation for 6-7 days, so that the mycelium can absorb sufficient oxygen to restore growth capacity, then switch to spraying water to preserve moisture, alternating dry and wet, to promote the occurrence of the next flush of mushroom buds. (7) Harvest at the right time to prevent overmaturity. Harvest when the mushroom cap has curled edges and the stem is moderate. Harvest once a day, and during the spring peak mushroom production period, sometimes harvest twice a day.