July 2013. What may be causing the leaf spots on Bougainvillea glabra? The plant is a single plant near a residence located in the north of Saint Lucia. That area is relatively dry, although we are in the rainy season now. There have been no unusual weather patterns or heavy rain showers within the last 3 weeks.

There were two suggestions: Cercosporidium bougainvilleae. Look to see if there are small, black dots in the white centers of the lesions. The other suggestion was Impatiens necrotic spot virus. A photo was sent of the symptom on Impatiens. [Editor: more likely to be a fungal spot].