Powdery mildew, which is caused by the fungus Leveillua rutae (syn. Oidiopsis haplophylli) on nasturtium (Tropaeolum majus L.), was found in southwest Florida for the first time in 2015 (Fayette et al. 2016). This two-page fact sheet describes the pathogen, its symptoms, and how to manage it. Written by Pamela D. Roberts, Katherine E. Hendricks, Francesco Di Gioia, Joubert Fayette, and Monica Ozores-Hampton and published by the Plant Pathology Department.
http://edis.ifas.ufl.edu/pp335