Cottonseed husks with plenty of cottonseed should not be directly used to grow Pleurotus ostreatus.

The cottonseed shell is composed of the shell left after the cottonseed is removed, the short cotton wool attached to the shell and a small amount of broken cotton kernels. Cottonseed hull is rich in nitrogen, phosphorus, potassium, cellulose and lignin, the ratio of carbon to nitrogen is 79-85:1, alkaline, outer pine and inner fruit, good air permeability and strong water storage, so it is the best raw material for edible fungus cultivation. However, cotton husk contains toxic substances, which will release aldehydes, ketones and acids after sterilization under high pressure or atmospheric pressure. these poisons will inhibit mycelium growth, delay budding, and cause adverse consequences such as small mushroom shape and poor mushroom quality. In particular, when the cottonseed content in the cottonseed shell is too high, the bacteria will be seriously affected, because the cottonseed contains gossypol, which will inhibit the mycelium growth when the content is more than 3%, and stop the mycelium growth when it reaches 5%. When cultivating edible fungi with cotton seed shell, the content of cotton kernel should not be too high, cotton wool should not be too long, and too much broken cotton kernel should be used after sieving, and the cotton seed shell should be fresh, the color should be gray or snow white, and the cotton seed shell should be dried in the hot sun for 1-2 days. Spray dichlorvos and pile up for 1-2 days before use. If Pleurotus ostreatus is cultivated with cottonseed shell raw material, it needs to be fermented in advance, so that the heap temperature is above 65 ℃ and fermented for 4-5 days, which can kill the bacteria and eggs in the material, decompose and release free gossypol.