Symptom Identification and Control Methods for Mushroom Brown Blotch Disease

Mushroom brown blotch disease, also known as dry bubble disease, is fairly widespread and occurs frequently on mushroom beds, causing great damage.

Symptoms: When the disease occurs, brown spots usually form on the stipe, cap, and gills, and become sunken; the mushrooms often lose their firmness and become deformed. In severe cases, the mushrooms rot. Diseased young mushrooms are mostly deformed, with the edge of the cap appearing serrated, or the stipe bending; some look like garlic bulbs, with the stipe thicker than the cap. When large mushrooms are affected, localized brown spots usually appear; the diseased mushrooms later dry out and become leathery, and a gray mold layer forms on the diseased parts. Unlike white rot disease, the diseased mushrooms rot more slowly, do not exude brown slime, and have no foul odor. In the early stage, the symptoms of white rot disease and brown blotch disease are similar.

Infection cycle: The primary source of initial infection by the pathogen usually comes from the casing soil, and contaminated soil is the main source of the disease. Subsequently, the main spread occurs when spores of the pathogen on diseased mushrooms are carried by airflow; manual operations and activities, such as contact with diseased mushrooms by hands and tools, can also spread it. This disease often first infects from residues left after mushroom harvesting, mainly from broken stipe wounds, and then spreads and expands.

Conditions for disease occurrence: The severity of the disease is closely related to temperature and humidity. Factors such as excessively high mushroom bed temperature, poor ventilation, moisture, and the piling of contaminated waste material on the mushroom bed can all lead to the occurrence of the disease.

Control methods: 1. Remove diseased mushrooms promptly. When diseased mushrooms are found, they should immediately be dug out together with the mycelium and the growing substrate 10 cm deep, then burned or buried deeply, and the diseased spots filled level with sterilized soil. At the same time, disinfect tools with formalin to prevent transmission of the pathogen. 2. Reduce temperature and humidity. Under the condition of not cooling the mushroom house, open windows for ventilation to lower the temperature and humidity. Control air humidity so that relative humidity does not exceed 95%, and lower the temperature to below 17°C. 3. Chemical control. To prevent the occurrence of the disease, before mushrooms emerge, spray the surface of the casing soil with Bordeaux mixture at 1:1:300, which can greatly reduce the infection rate. Alternatively, for every 100 sq m of mushroom bed, use 100 g carbendazim or 200 g thiophanate-methyl plus 100-150 kg of water to spray the mushroom bed surface. 4. Other measures. If the disease still continues to develop after the above measures are taken, all the casing soil can be removed, replaced with disease-free soil, and re-cased, while controlling the factors that cause the disease.