What are the symptoms of yellow blotch disease in oyster mushrooms?

Yellow blotch disease of oyster mushrooms is a disease caused by Pseudomonas bacteria, which shows a negative reaction to Gram staining. This disease is a bacterial disease, it is widely present in nature, and it attacks both oyster mushrooms and button mushrooms.

Symptoms: In the early stage of infection, small speckled yellow diseased areas appear on the caps; as the fruiting bodies grow, they expand and infect other fruiting bodies; subsequently the color deepens and spreads to the entire cap, and the whole mushroom turns yellow. The affected fruiting bodies become water-soaked but are not sticky and do not rot, and especially in black oyster mushrooms the color difference after yellow blotches appear is extremely obvious. In the late stage of infection, the fruiting bodies secrete yellow-brown water droplets, the diseased specimens stop growing, then shrivel and die. In severe cases, multiple flushes of mushrooms all become diseased. The blotches generally occur in the shallow layer, and the flesh more than 3 mm below the surface rarely changes color.

Cause: The growing substrate, casing soil, and water used in management are the main sources of the pathogen on the mushroom bed, and air, insects, people, and splashing water can also help spread it. High temperature and high humidity strongly favor the disease, and it grows and reproduces quickly; under suitable conditions it can infect mushrooms and produce blotches within a few hours. It is especially likely to trigger this disease when the temperature remains stable above 20°C, humidity is above 95%, and carbon dioxide concentration is relatively high; even when the temperature is around 15°C, if the mushroom shed humidity approaches saturation and there is no ventilation, the incidence rate is still relatively high; when the water used in the substrate and the mushroom shed is unclean, the disease is also very likely to occur; in addition, during spring and autumn when temperature fluctuates greatly, this disease is very prone to becoming epidemic.