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What causes white lumps to grow on oyster mushrooms

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In recent years, a serious new disease has occurred in oyster mushroom production. This disease mostly occurs after the first flush of mushrooms is harvested, and a small number of cases occur after the second and third flushes. When the disease first appears, a small number of white dots grow on the surface of the oyster mushroom substrate, forming nodule-like shapes that closely resemble undifferentiated oyster mushroom fruiting body primordia. They gradually grow larger and merge into a single mass, and later turn brown. The disease is highly contagious, and once it occurs, mushrooms no longer grow normally. Growers call this disease "white lump disease." According to relevant reports, this disease once occurred on shiitake logs in Japan and was called "large button

In recent years, a serious new disease has occurred in oyster mushroom production. This disease mostly occurs after the first flush of mushrooms is harvested, and a small number of cases occur after the second and third flushes. When the disease first appears, a small number of white dots grow on the surface of the oyster mushroom substrate, forming nodule-like shapes that closely resemble undifferentiated oyster mushroom fruiting body primordia. They gradually grow larger and merge into a single mass, and later turn brown. The disease is highly contagious, and once it occurs, mushrooms no longer grow normally. Growers call this disease "white lump disease."

According to relevant reports, this disease once occurred on shiitake logs in Japan and was called "large button mushroom." Its mycelium is white, lusterless, and whisker-like, and to the naked eye it looks very much like oyster mushroom mycelium. When reproducing, it gives off an unpleasant odor. It is a parasitic fungus that uses oyster mushroom mycelium as its nutrient source. Its infection method is to secrete an enzyme that destroys the cell walls of the mycelium, absorbs the nutrients in the mycelium, and causes the oyster mushroom mycelium to die. Once this disease occurs, there is currently no method for a complete cure, but as long as attention is paid to prevention, the disease can be effectively prevented. Through practical experience, our institute has summarized the following control methods for the reference of growers:

1. Replace the variety to enhance disease resistance. Practice has shown that in the same area, repeatedly cultivating the same variety leads to a high incidence rate. It is best to replace the new variety once a year, and especially to select and breed varieties with strong disease resistance, thus laying a solid foundation for a bumper harvest in cultivation.

2. Place them correctly to prevent mycelial burning. In recent years, most oyster mushroom fruiting has used wall-style three-dimensional soil casing. This method is easy to manage, has high yield, and makes replenishing water convenient, but its drawback is that it does not dissipate heat easily and readily causes mycelial burning. Because the soil itself also carries pathogens, this disease is extremely likely to occur. It is best to adopt the method of no soil casing, single-row placement, and fruiting from both ends. Between layers, use small bamboo poles or sorghum stalks as spacers, and leave a certain gap between bags to help lower the temperature. With single-row placement, as long as water is replenished promptly and management is strengthened, high yield can also be obtained. If soil casing is used for fruiting, the following points should also be noted: ① Strictly sterilize the soil, fumigating the soil with formaldehyde; ② Cover with moist soil, not mud, because synthetic mud tends to compact, has poor air permeability, cannot meet the oxygen required for oyster mushroom growth, and exhaust gases cannot be discharged promptly; ③ Replenish water in the water trough appropriately. If too much water is replenished, the water content in the substrate becomes too high, causing mycelial oxygen deficiency, thin and weak mycelium, poor disease resistance, and susceptibility to disease.

3. Integrate control measures to eliminate sources of infection. ① During the mycelial growth period, spray caustic soda water once every 10 days. This not only effectively sterilizes but also removes acidic substances in the mushroom house, making the mycelium grow thick and strong with strong disease resistance; ② Before fruiting, spray the space and walls of the mushroom house once with 1‰ carbendazim for sterilization. After each flush of mushrooms is harvested, spray the substrate surface, space, and walls once more with 1‰ carbendazim; ③ During the fruiting period, be sure to keep the mushroom house clean, promptly clean up mushroom bases, and eliminate hidden dangers; ④ After fruiting is finished, promptly remove the spent substrate and keep it away from the mushroom house; ⑤ Disinfect and sterilize the mushroom house promptly. Methods such as spraying and washing with caustic soda or lime water, or burning sulfur for fumigation can be used. If conditions permit, burning with fire can also be used for sterilization, creating favorable conditions for the next cultivation. As long as the measures are reasonable, the occurrence of this disease can be completely avoided.

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