Jun 2, 2017
#1239 - Miyagia pseudosphaeria - Sonchus Rust
And then, tonight, as I was getting these photos together to post on my blog, I noticed that many of the Sowthistle leaves had little yellow pimples on them, surrounded by dark pinkish rings - it soon figured out that it’s a another specialist, the Sonchus Rust Fungus (Miyagia pseudosphaeria).
The fungus was first noticed in Australia 20 years ago or so, but has no real effect at controlling the weed. Nor are the aphids, and their predator has its own problems, in the form of the wasp. True, it all reaches a balance eventually, but that balance is an invasive weed occupying habitat better reserved for Australian native plants, if you can find any that will survive beside driveways.