Causes and Control Methods of Yellow Mushroom Disease in Oyster Mushrooms

In recent years, the cultivated area of oyster mushrooms has continued to increase, but due to poor management by growers, weak awareness of disease prevention, and other reasons, the incidence of yellow mushroom disease in oyster mushrooms has shown an upward trend year by year. In some mushroom sheds, after one flush of mushrooms, no more mushrooms appear for a long time; in others, the small mushrooms that do appear turn yellow before growing up, then shrivel and die, leading to a decline in oyster mushroom quality and making it difficult to increase yield. For this reason, the author studied the causes of the disease and integrated control techniques, and reports as follows:

1. Disease symptoms. Yellow mushroom disease mostly starts from the caps of young mushrooms or the junction between the stipe and cap of small mushrooms. After onset, pale yellow spots appear on the caps of young mushrooms or in the depressions of the caps of small mushrooms. The young mushroom bodies become sticky, stop growing, and die; small mushroom bodies grow slowly and lose elasticity, breaking apart at the slightest touch, after which the mushroom bodies become sticky and shrivel, giving off a foul rotting odor. The disease spreads rapidly, causing the cultivation substrate surface to become sticky and cease producing mushrooms.

2. Causes of the disease. The pathogen of yellow mushroom disease in oyster mushrooms is Pseudomonas. (1) This bacterium is suited to growing on substrates that are moist and rich in organic matter; under conditions of high temperature and high humidity with poor ventilation, its occurrence and growth are favored. (2) The environment of old cultivation sites deteriorates, and disinfection is not thorough. (3) Discarded spent substrate, defective mushrooms, and mushroom stipes are scattered everywhere in the shed; the dirty and messy conditions give the pathogen a place to inhabit and reproduce. (4) Currently, oyster mushroom cultivation mainly uses raw or fermented substrate, and the substrate itself carries the bacterium, causing the disease. (5) The water or casing soil used carries the bacterium. (6) Poor disease resistance of the strain or poor spawn quality, as well as poor management by growers, leads to thin mycelium in the cultivation bags and reduced resistance, ultimately resulting in infection by the pathogen and disease onset.

3. Preventive measures. (1) Select strains adapted to the local environment with strong disease resistance, such as Heipingwang, Huiping Kangbing No. 2, P89, and other strains, which generally are not prone to the disease or develop it only mildly. Do not plant the same strain year after year at the same site; it is advisable to change varieties once every 2 to 3 years. (2) Select age-appropriate spawn that is free of contamination by foreign microorganisms, with thick white mycelium and robust growth. (3) Select high-quality raw and auxiliary materials that are free of mold, rot, insects, and contamination. The cultivation substrate should be sun-dried before use, and fungicidal drugs such as Kemiewang or carbendazim at 0.1% of the dry material weight should be added. (4) Old sites should not be used year after year; if used, sterilization and insecticide treatment must be carried out 1 month before the cultivation bags enter the shed. For mold control, carbendazim 500x solution, Benjunqing 500x solution, etc. can be used; for bacteria control, bleaching powder 200x solution, agricultural streptomycin 500x solution, Wanxiaoling 2000x solution, etc. can be used; for insect control, dichlorvos 500x solution, beta-cypermethrin 1000x solution can be used, sprayed on the shed floor, walls, and the surrounding environment, once a week. Two to three days before the cultivation bags enter the shed, seal the shed and fumigate with sulfur for 24 hours. (5) Strengthen management during the mycelium-running period of the cultivation bags to improve the mycelium's resistance to disease and contamination. During the fruiting period, control the temperature and humidity in the shed well. Excessively high temperatures are unfavorable for the growth of generally wide-temperature-type or low-temperature-type strains, and instead provide a suitable temperature environment for various foreign microorganisms and bacteria; high humidity in the shed is favorable for oyster mushroom growth, and at the same time also suitable for the growth of various foreign microorganisms. (6) The mushroom shed should be built in a place with good ventilation and convenient drainage. Ventilation in the shed should be smooth, and the vents should be set up so that flowing air can pass over every substrate surface, with no dead corners for ventilation. Adjust ventilation time promptly according to factors such as temperature, weather, and wind speed. (7) When using casing cultivation, the casing material must be treated for sterilization and insect killing. (8) Maintain good sanitation in the shed. After harvesting mushrooms, promptly remove leftover mushrooms, keep the floor clean, and regularly spread lime powder for environmental disinfection.

4. Post-onset treatment. (1) Once the disease occurs, immediately remove the diseased mushrooms, clean the substrate surface, stop spraying water, and increase ventilation. (2) Spray 1% bleaching powder once on the walkways, walls, and surroundings outside the shed, and spray the substrate surface with a 1:500 dilution of carbendazim plus agricultural streptomycin, 1 to 2 times per day; spraying continuously for 4 days can control the spread of the disease. Other drugs such as Huangguqing, Wanxiaoling, Huangbanxiao, Xijunsha, Bingjunlimie, etc. can be used alternately according to standard dosages for control.