"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

December 31, 2010

December 31 - Guignardia bidwellii

As you raise your glass of champagne tonight and toast this wonderful year of biodiversity, don't forget the parasites. And, to help you remember, today's parasite is after the grapes cultivated for wine. Guignardia bidwellii is a species of ascomycetous fungus that causes a disease called "Black rot" in many varieties of grapes in North America and now Europe, South America, and Asia as well. The vectors of this disease are not mosquitoes nor plant bugs, but rather raindrops, which splash the infective spores onto uninfected plants. Infection of the fruits will cause the grapes to shrivel up into what are known in the industry as "mummies" and these can serve as a good place for the fungus to overwinter.


  1. Congratulations on a successful year of parasite biodiversity! Happy New Year!

  2. Wow I can't believe it's already a whole year. Congrats and thanks for all the posts. What's going to happen to this blog after today?

  3. So that's what it is! My great-uncle had a vineyard and we would sometimes help pick the grapes. I just thought it was a self-pruning effect when the environmental conditions weren't optimal for full growth. Thank you for all your wonderfully informative, entertaining, and intermittently horrifying posts.