First Report of Smoketree Rust Caused by Pileolaria cotini-coggygriae in the Midwestern United States

Abstract

Smoketrees (or smoke bush, Cotinus spp.) are large deciduous trees or bushes in the Anacardiaceae. European smoketrees ( Cotinus coggygria Scop.) are valued as an ornamental for their unusual flowers and striking autumn color. In June 2020, leaves of C. coggygria from a single tree in a home landscape in Franklin, Indiana, were found to be infected. Leaves with evidence of rust disease—plant tissue distortion with visible fungal growth—were submitted to the Purdue Plant and Pest Diagnostic Laboratory. Morphological identification was supported by extracting DNA from the specimen, sequencing the 28S region of the nuclear ribosomal DNA repeat, and comparing this to another accessioned P. cotini-coggygriae specimen (PUR018082; GenBank accession #MZ188974) from the Arthur Fungarium (PUR), resulting in 100% identity shared. This is the first vouchered record of P. cotini-coggygriae in the Midwestern United States.