Trichoderma viride is the green mold that is such a problem when cultivating mushrooms. The major reason why clean techniques are so important when growing mycelium.
from http://synapse.koreamed.org/ViewImage.php?Type=F&aid=304642&id=F2&afn=184_MB_31_2_74&fn=mb-31-74-g002_0184MB
This paper is published in full online.
Compare these images to a scanning electron microscope image of oyster mushroom mycelium
from http://www.sciencedirect.com/science/article/pii/S0260877402002698
According to the article, in Korea, the main diseases with oyster mushrooms are green mold caused by Trichoderma, black-gray velvet caused by Trichrus spiralis, fire mold caused by Neurospora sp., brown spot of Pseudomonas tolaassi, and virus in Korea (Kim et al., 1995,2000). Trichoderma cf. virens (70.8%), T. longibrachiatum (16.7%) and T. harzianum (12.5%). T. longibrachiatum and T. harzianum were mainly isolated from sawdust based substrate and T. cf. virens was isolated from the rice straw and cotton waste substrates
Here are some other micro-images of this green mold.
from http://www.sci.muni.cz/ueb/mik/Miniatlas/tri.htm
from http://www.schimmel-schimmelpilze.de/trichoderma-viride.html