Contamination in mushroom cultivation and mycology can be caused by a variety of factors. Some common causes include the use of contaminated substrates or spawn, inadequate sterilization or sanitation practices, and the introduction of spores or other contaminants from the surrounding environment.

Contaminants can take many forms, including bacteria, molds, and other fungi, and can compete with or even destroy the desired mycelium or fruiting bodies. It is essential to maintain a sterile environment when working with mycology, as well as to use high-quality materials and follow proper procedures for sterilization and sanitation.