Nectria ascospores magnified 400 times(dark field light microscopy) 

Red perethecia, fruiting bodies that contain asci (spore sacs)

Nectria is a genus of Ascomycete fungi. They are usually harmless saprotrophs on decaying wood, but some species also occur as parasites of fruit trees. Some species are significant pests, causing diseases such as apple canker, and Nectria twig blight.

This pictue is maginified 115 times.  The picture shows the fruiting bodies of this fungi that produce spores in the spring.  The fungi lives as a filamentous growth (fungal hyphae) inside of the tree bark.