Mycelial film is a formidable enemy of high-yielding oyster mushrooms, and growers must be vigilant

Casing soil cultivation is an important measure for obtaining high yields of oyster mushrooms. However, before fruiting or after the first flush is harvested, the casing soil surface often forms an impermeable, airtight mycelial film from vigorously growing aerial hyphae, affecting fruiting. This mycelial film consumes a large amount of nutrients, causing reduced oyster mushroom yields, and must be prevented in production.

Causes of mycelial film formation: First, when bag-cultivated oyster mushroom substrate is not fully colonized before casing soil is applied, the hyphae undergo a second vegetative growth on the surface, forming a mycelial film; Second, the cultivation substrate formula is unreasonable, with excessive nitrogen content causing blockage and an imbalanced carbon-to-nitrogen ratio; Third, the covering soil has excessively high nitrogen content, or urea has been additionally added; Fourth, the casing soil is heavy in texture and compacted; Fifth, the temperature during the fruiting period is too high with small temperature differentials, or the mushroom shed (room) has poor ventilation, is too dark, is overwatered, or has excessive humidity.

Countermeasures to prevent mycelial film formation: 1. The hyphae in the cultivation bags must be fully colonized, and casing soil and fruiting should begin only when the mycelium starts transitioning to reproductive growth. The standard for full colonization is: the mushroom bags feel light and buoyant when handled, the bag surface is wrinkled with yellowish-brown water accumulation inside, or small mushroom primordia are observed. 2. Use a reasonable cultivation substrate formula and strictly control the carbon-to-nitrogen ratio of the substrate according to standards. The cultivation substrate formula can be flexibly adjusted according to the variety being cultivated. 3. Use aged vegetable garden soil for casing, preferably light loam. Some plant ash and compound micro-fertilizer can be added to the soil, but urea should generally not be added. 4. After casing, spray water sparingly and evenly, just enough to moisten the bottom soil. Strengthen the management of the mushroom shed (room); during hot seasons, expand ventilation at night to widen the day-night temperature difference and promote early primordium formation. 5. Once mycelial film forms, use a wire hook to repeatedly scratch and break the film until the surface hyphae stop growing. At the same time, increase temperature differential stimulation and ventilation, control watering, and appropriately increase light exposure. In this way, normal fruiting can generally resume after 10 to 15 days.