Degradation of strains will lead to slow growth of mycelium, resistance to the environment, bacteria, etc. weakened, the formation of fruiting bodies in advance or postponed, mushrooming tide is not obvious and so on. There are many reasons for the degradation of strains, among which impure strains and gene mutations are the main reasons. In addition, excessive temperatures and mixed cultivation of different strains can cause degradation of strains. The measures for preventing the degradation of strains include: ensuring pure culture of strains, taking care not to use bacterial strains contaminated with bacteria, and not connecting cultures at close distances; strictly controlling the number of strains passaged, reducing mechanical damage, and ensuring the viability of strains; Cold storage strains, low-temperature strains such as mushrooms, mushrooms, etc., are conducive to the preservation of mycelium viability at 4°C, and high-temperature strains such as straw mushroom are good for preserving the vitality of mycelia at 16°C; avoiding single cultures Many times in the base; strains should not be used for too long, over ageing bacteria will appear to be aging, and aging and degradation are organically linked, weak viable strains are prone to degradation; strains should be regularly rejuvenated, suitable Warm, suitable pH, sufficient oxygen, no bacteria culture and other conditions; annual spore separation, sexual reproduction to find good strains, tissue separation to consolidate the genetic characteristics of good strains.