"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

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.


  1. This is the first half-way informative info I have found on Cephaleuros. Laboratory has identified spots on some leaves from my coffee trees as Cephaleuros sp. Although I got hundreds of hits none seem to describe what the lab identified. You have rekindled my faith in our lab.
    Thank you Susan

  2. i have a peanut plant and it has dark rust spots and it is from rust and from my filtered rain water because that one very time when i dripped the rust part of the water on the plant and now it keeps growing new leaves with the rust spots on the tips of the leaves and i have no clue of how to kill the rust spots with out killing the plant on my plant its darker than on your plant picture above so mine has it pretty bad, and the few spider mites that i have don't even bug the plant they just stay in the dirt.