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1 March 2006 Rudbeckia auriculata Infected with a Pollen-mimic Fungus in Alabama
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The fungus Fusarium semitectum infects the flowering heads of Rudbeckia auriculata at two sites in Alabama. This is the first report of a fungal agent infecting this globally rare species. The fungus produces orange-tinged or pinkish-white spores on the flower heads and renders infected flowers sterile. Fungal spores superficially resembled pollen and are picked up by the main pollinator, the composite specialist bee Andrena aliciae, which serves as a dispersal agent for the fungal pathogen. Fungal spores were found attached in higher ratios in those areas of the bee's body that come into most direct contact with the flowering heads during feeding. The rate of spread of the fungus on potted plants indicated significant negative correlations between number of infections and the distance from the fungal source. Fusarium colonies were isolated from the entire length of flowering stems, and apparently invade vegetative portions of the plants. As R. auriculata is a perennial plant that reproduces almost exclusively by the production of short stolons, the fungus poses no serious threat to its immediate existence.

Alvin R. Diamond, Hanan El Mayas, and Robert S. Boyd "Rudbeckia auriculata Infected with a Pollen-mimic Fungus in Alabama," Southeastern Naturalist 5(1), 103-112, (1 March 2006).[103:RAIWAP]2.0.CO;2
Published: 1 March 2006

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