Wednesday, March 7, 2012
Alaskan rust spores identified!
At long last, the news I've been waiting for! The mysterious Alaskan orange goo, thought at first to have been eggs of something, or possibly the dinonflagellate Noctiluca, later discovered to be rust spores, has been positively identified. The mystery rust is Chrysomyxa ledicola, which causes spruce-labrador tea needle rust. The spores identified were the urediniospores, which is known as the repeating stage of macrocyclic rusts. It is common for rusts to produce ba-jillions of spores, especially urediniospores, to keep reinfecting their alternate hosts. In this case, that alternate host is labrador tea Ledum spp., though the NCCOS webpage lists it as Rhododendron tomentosum. That name isn't accepted by PLANTS.usda.gov, which is my source for this kind of information. That fact helps explain how the source of the orange goo was originally so mysterious. While the primary host, spruces (Picea spp.), are a group that would be difficult to hide that many spores on without someone taking notice, labrador tea is a common understory plant that wouldn't raise as many alarm flags.