First Report of Melampsora euphorbiae on Poinsettia (Euphorbia pulcherrima) in Norway

Melampsora euphorbiae (Schub.) Cast. is reported from all continents but Antarctica. The rust fungus is living on a great number of Euphorbia species. In Norway it is found on five Euphorbia species (wild growing or cultivated outdoors), including the common weed sun spurge (E. helioscopia L.). On this host the fungus is known in the country north to North Trøndelag County. To our knowledge M. euphorbiae on poinsettia (E. pulcherrima Willd.) has previously been reported only three times, namely in India (2), Tanzania (5), and Mauritius (1). M. euphorbiae-dulcis Otth. has been reported on poinsettia in Kenya (4). The fungus is autoecious, but has been found to have three specialized forms (3). None of them are reported on poinsettia. In September 2006, necrotic spots (Fig. 1 and 2) were observed on leaves of poinsettia cv. Cortez White from a greenhouse in Troms County in northern Norway. An examination of the spots revealed that they were caused by M. euphorbiae. Uredinia (Fig. 3) and telia (Fig. 4) were present in the material, both on the lower side of the leaves.