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United States Department of Agriculture

Agricultural Research Service

Title: First Report of Smut Caused by Microbotryum Silybum on Silybum Eburneum

Authors
item Souissi, Thouraya - INST NATL AGRON TUNISIE
item Berner, Dana
item Smallwood, Emily

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 22, 2005
Publication Date: November 1, 2005
Citation: Souissi, T., Berner, D.K., Smallwood, E.L. 2005. First report of smut caused by microbotryum silybum on silybum eburneum. Plant Disease 89:1242

Interpretive Summary: Ivory thistle is a problematic weed in northern Tunisia. The fungus Microbotryum silybum is a known pathogen of milk thistle. Milk thistle is an invasive weed in the U.S., and plants related to it have been evaluated for susceptibility to the fungus at the Foreign Disease-Weed Science Research Unit, USDA, ARS, Fort Detrick, MD. Because of the close relationship of the two thistles, both species were tested for susceptibility. Plants of milk thistle (40%) and ivory thistle (67%) became infected. Both species reproduce solely by seeds. Since this fungus prevents seed production, it is a potential biological control agent for both species. This is the first report of this fungus parasitizing ivory thistle.

Technical Abstract: Silybum eburneum is a problematic weed in northern Tunisia. The smut fungus Microbotryum silybum is a known pathogen of S. marianum.. S. marianum is an invasive weed in the U.S., and plants related to S. marianum have been evaluated for susceptibility to M. silybum at the Foreign Disease-Weed Science Research Unit, USDA, ARS, Fort Detrick, MD. Because of the close relationship of S. eburneum to S. marianum, both species were tested for susceptibility. Plants of S. marianum (40%) and S. eburneum (67%) became infected. Both species reproduce solely by seeds. Since M. silybum prevents seed production, this fungus is a potential biological control agent for both species. This is the first report of M. silybum parasitizing S. eburneum.

Last Modified: 7/28/2014
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