Every time I use the microscope I’m amazed at the structure and delicacy of nature. Capturing this beauty on camera can be challenging, but I hope you enjoy the pictures I share on this blog!
Today’s picture is of the conidia, or asexual spores of the pathogen Sphaeropsis sapinea which causes Sphaeropsis Blight on pine trees. This disease is better known as Diplodia Tip Blight due to the fact that the asexual stage, named Diplodia pinea, is more frequently seen than the sexual stage (the aforementioned Sphaeropsis). It’s the same pathogen, but because the life stages were discovered independently they were given different names and those names have stuck, at least in common parlance.
Diplodia spores are very large, and have a distinctive color and shape: they look like root beer-flavored jellybeans to me. The clear spores visible in the picture are immature condia. The structure on the left of the picture shaped like a dark, indistinct “C” is the cross-section of the Diplodia fruiting body. Fruiting bodies are produced by fungi and contain spores. There are a number of different types of fruiting bodies; Diplodia produces one called a pycnidium (plural: pycnidia). The grey fuzzy-looking structures on the inside of the fruiting body are where the immature conidia are formed. Once mature, the spores ooze out of the pycnidia in wet weather and spread via wind, splashing rain, insects, and pruning tools.
For more information about Diplodia Tip Blight including pictures of symptoms on needles and pinecones, see my article in the Home, Yard, and Garden Pest Newsletter: Diplodia Tip Blight on Pine