What are the quality requirements for straw mushroom spawn production?

Whether the straw mushroom spawn is isolated by yourself or introduced from elsewhere, it must undergo a fruiting test, and only after confirming it is a high-yielding, high-quality strain may it be expanded for culturing, so as to avoid economic losses. Quality requirements for qualified spawn (for reference):

(1) The mycelium is pale yellow and transparent, with many or no chlamydospores (varying depending on the variety), the mycelium is evenly distributed throughout the bottle, and the moisture content of the substrate is suitable (about 65%).

(2) The spawn age is appropriate, fresh, robust, and strong in growth vigor.

(3) Free of contaminating microorganisms and pests.

Any of the following conditions indicates unqualified spawn:

(1) The mycelium is white and transparent, with no or very few chlamydospores; this is young spawn and must continue to be cultured until it reaches the appropriate age before use.

(2) The mycelium gradually becomes sparse, but a large number of chlamydospores fill the substrate; the mycelium is yellow and dense like a mycelial mat, and the upper layer of mycelium shrinks. This is old spawn, which has a relatively large impact on yield and is not suitable for use.

(3) The mycelium is sparse and transparent, thin like spider silk, indicating that the mycelium has absorbed insufficient nutrients and has few branches. This is commonly seen when the substrate is not thoroughly sterilized and a large number of Bacillus subtilis multiply on the surface of the straw, affecting the straw mushroom mycelium's nutrient absorption. Such spawn is also not suitable for use.

(4) The mycelium gradually dies out, and the inner wall of the bag is covered with a layer of crawling powder; this is mites, a type of pest, feeding on the mycelium, and it should be discarded.

(5) The spawn bag is heavy, the mycelium grows weakly, and the chlamydospores clump into masses; this is caused by excessive moisture in the substrate, and the spawn quality is poor.

(6) The mycelium is dense and pure white, sometimes with small sclerotia, and may be mixed with contaminating microorganisms. If ink-colored umbrella mushrooms grow in the bottle, it proves infection by Coprinus fungi and it should be discarded.