Disease Note

Corynespora Bract Spot of Euphorbia pulcherrima in Florida. A. R. Chase, IFAS, University of Florida Agriculture and Research Education Center, Apopka 32703. G. W. Simone, Department of Plant Pathology, University of Florida, Gainesville 32611. Plant Dis. 70:1074. Accepted for publication 11 July 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1074d.

A bract spot of poinsettia (Euphorbia pulcherrima Willd.) has occurred each winter since 1982 in central Florida nurseries. Black lesions up to 3 cm in diameter appear on bract margins and tips and sometimes on leaves, often resulting in plant loss. Isolations yielded Corynespora cassiicola (Berk. & Curt.) Wei. Five poinsettias each were inoculated with one of four conidial suspensions (1 × 10⁴ / ml) or water to runoff under intermittent mist for 24 hr before and 14 days after inoculation. Typical lesions occurred on bracts of plants inoculated with C. cassiicola, and the pathogen was reisolated from symptomatic tissue only. Inoculations of poinsettia with isolates of C. cassiicola from Aeschynanthus pulcher (Blume) G. Don (1), Ficus benjamina L. (2), Ligustrum sinense Lour., Lycopersicon esculentum L. (Mill.) Karst ex Fariv., and Saintpaulia ionantha H. Wendl. resulted in typical bract spot for each isolate within 14 days. No indication of host specificity was noted (2).