Abstract
Rudbeckia laciniata (cutleaf coneflower in the USA; margarida-amarela in Brazil) is a member of the Asteraceae and native to North America. It is traditionally used in the USA as a medicine, as well as being grown widely as an ornamental in the USA and abroad. During 2004 and 2005, R. laciniata plants cultivated at the Campus of the Universidade Federal de Vicosa (Minas Gerais, Brazil) were found to be attacked by a severe foliage disease. Primary leaf symptoms are circular to elliptical, dark brown to nearly black leaf spots (eyespots), 1·0‐7·0 × 1·5‐17·0 mm diameter, and surrounded by a yellow halo. The spots coalesced, leading to extensive leaf necrosis with occasional shot-holes. Petiole and stem lesions are brown, elongated and irregularly dispersed. A dematiaceous hyphomycete with the following morphological features was consistently found associated with the lesions: conidiophores formed singly (150·0‐262·5 µ m long × 7·5‐12·5 µ m thick), 3‐8 septate and brown; conidia fusiform, obclavate to subcylindrical, straight or curved (62·5‐ 154·0 × 18·0‐22·5 µ m), subhyaline to brown, 5‐16 distosseptate. The organism conformed most closely to Corynespora cassiicola , a highly polyphagous fungus (Ellis, 1971). A sample was deposited in the local herbarium (VIC 28791). Pure cultures of C. cassiicola were cultivated from sporulating leaf lesions on V8 juice agar. Three unwounded healthy plants were brushinoculated with a conidial suspension containing 4·4 × 10 5 conidia mL − 1
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