Trichoderma harzianum mycelium begins as a gray color and then changes to white becoming very dense. After fruiting, its spores turn it a dark green. There are many other types of molds that also are green associated with mushroom compost.
To infest a mushroom crop, Trichoderma first must have its spores introduced. The spores can adhere themselves to employees and their clothing, as well as to equipment and plastic surfaces around a mushroom farm, flies or on mites.
Spores must exist in sufficient numbers and correct conditions must prevail. Compost and environmental conditions during composting have been found to be associated occasionally with green mold development.
The control of this disease is two-fold, proper Phase I and II composting and good hygiene/sanitation to eliminate spore loads and infection opportunities.