May 16, 2010
May 16 - Cephaleuros virescens
Of all of the nasty parasites out there, this one just might be my personal least favorite - only because it attacks so many of my very favorite plants - coffee, tea, avocado, mango, vanilla, and cacao. Cephaleuros virescens is a parasitic green algae (sometimes known as "red rust" because of the characteristic spots that it makes) that is common in sub-tropical and tropical parts of the world. Although it is generally fairly harmless to plants, it can cause economic woe when it infects crop plants such as the ones I just mentioned, via lowered rates of photosynthesis or causing the fruits to look damaged and spotty. The life history of these algae is such that they alternate between sexual and asexual reproduction. When spores are blown or splashed onto a plant, the parasite grows into the epidermis of the leaf or fruit, where they form disc-like, filamentous thalli. This parasite has become a particular problem in Hawai'i where it seems to have a special penchant for guava.