Colorized scanning electron micrograph of rust on a rose leaf. Rose rust is a disease specific to roses and is caused by the parasitic fungus Phragmidium tuberculatum and some other closely related species. This disease occurs during spring and persists until the leaves fall. This images shows rose rust and tiny pores in the leaf (called stomata) visible on the surface of the leaf. Stomata are essential for plant gas exchange. The main group of spores from the fungus is 200uM.
Credit: Annie Cavanagh, Wellcome Images