August/September 2024

Winter yellow rust (Puccinia striiformis), a fungal pathogen, on the leaf of a purple false brome (Brachypodium distachyon).
Photo: Bernhard T. Werner

The fungus is green in color, while the plant appears yellowish/reddish. In the center you can see the urediospore (dotted ball) from which the fungus has attacked the plant.
The thorn-like structures on the leaf below are trichomes (plant hairs) of the plant.

For more information:
Dr. Bernhard T. Werner, Phytopathology