Control Methods for Yeast Disease in Lingzhi (Ganoderma lucidum)
Yeast is a type of ascomycete fungus lacking filamentous hyphal structure, widely distributed in nature. During the production and cultivation of edible mushroom spawn such as lingzhi (Ganoderma lucidum) and silver ear (Tremella fuciformis), it can contaminate culture media and substrate, mainly contaminating the substrate, causing substrate deterioration and inhibiting mycelial growth.
Symptoms: When yeast infects, it mostly starts from the middle of the silver ear substrate, causing the substrate to ferment and deteriorate, with a sour alcoholic odor being released, affecting mycelial growth and development, and consequently affecting yield and quality.
The pathogen belongs to the subphylum Ascomycotina fungi. On potato sucrose agar medium, the colonies of this fungus grow in a paste-like or gelatinous form, with colors including milky white, pink, and creamy yellow. Some are sticky, some have entire margins, some have smooth surfaces, and some have wrinkled surfaces. Under the microscope, blastospores can be observed. Blastospores are colorless, single-celled, and similar in morphology to the mother cell.
Disease characteristics: Yeast lives on organic matter, and spores spread through airflow. During spawn production or raw material cultivation, due to incomplete disinfection and sterilization, excessive and tightly packed substrate in bottles and bags, and close arrangement between bottles and bags, this fungus is prone to occur. High temperature and high humidity are favorable for yeast germination and reproduction. Excessive bed material thickness and excessively high substrate moisture content will both lead to substrate fermentation and deterioration.
Control Methods
(1) During spawn production, use an appropriate amount of spawn bags to avoid packing the substrate too tightly. During sterilization, maintain appropriate spacing between bottles and bags to facilitate even dispersal. For stock cultures and cultivation cultures, the atmospheric intermittent sterilization method should not be used. Atmospheric one-time sterilization should be maintained at 100°C for at least 8 hours.
(2) Perform aseptic operation during inoculation, and workers must strictly follow inoculation procedures.
(3) During cultivation, mix 0.2% of 25% carbendazim or 0.1% thiophanate-methyl based on the dry material weight into the substrate. Maintain appropriate moisture content and temperature of the substrate. Spray with clean water to reduce the occurrence of pathogens.
(4) During cultivation and production, if the substrate temperature is found to be too high and a sour odor is released, promptly drench the substrate with lime water (pH=13-14) to control yeast reproduction.
Commonly used agents: carbendazim and thiophanate-methyl.