ARS | Publication request: FIRST REPORT OF AN OVARY SMUT OF ITALIAN THISTLE CAUSED BY MICROBOTRYUM CARDUI IN GREECE

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2006
Publication Date: May 1, 2006
Citation: Berner, D.K., Mcmahon, M.B., Kashefi, J., Erbe, E. 2006. First report of an ovary smut of italian thistle caused by microbotryum cardui in greece. Plant Disease. 90:681.

Interpretive Summary: Italian thistle is a problematic invasive weed in the U.S. and a target of biological control efforts. In May, 2005, diseased flower heads of Italian thistle were found in an abandoned field in Halkiades, Greece. In most cases, all flower heads on diseased plants bore signs of a smut fungus. When diseased heads were split open, all of the flowers within the head were filled with powdery masses of fungus spores. Diseased heads were collected and sent to the quarantine facility of FDWSRU, USDA/ARS, Fort Detrick, MD where the fungus was identified as Microbotryum cardui (A. A. Fischer Waldh.) Vánky. Italian thistle is an annual plant that reproduces solely by seeds. Given the lack of seed production on smutted plants, this fungus has great potential as a biological control agent for Italian thistle in the U.S.

Technical Abstract: Italian thistle (Carduus pycnocephalus L.), family Asteraceae, is a problematic invasive weed in the U.S. and a target of biological control efforts. In May, 2005, smutted capitula of Italian thistle were found in an abandoned field in Halkiades, Greece. In most cases, all capitula of diseased plants were smutted. When diseased capitula were split open, the ovaries in all florets within the capitula were filled with powdery masses of smut teliospores. Diseased capitula were collected and sent to the quarantine facility of FDWSRU, USDA/ARS, Fort Detrick, MD where the fungus was identified as Microbotryum cardui (A. A. Fischer Waldh.) Vánky. Italian thistle is an annual plant that reproduces solely by seeds. Given the lack of seed production on smutted plants and the systemic nature of the disease, this fungus has great potential as a biological control agent for Italian thistle in the U.S.