Occurence of Boeremia exigua var heteromorpha on Nerium oleander in the United Kingdom.
In August 2010, diseased samples of oleander (Nerium oleander) were received from the Plant Heritage National Plant Collection located in Devon, UK. Symptoms included leaf spots, stems lesions and dieback. The disease was aggressive and a threat to the collection having affected 50% of the plants. Microscopic examination revealed the presence of irregularly scattered globose pycnidia associated with the necrotic lesions. Based on morphological and growth characteristics on agar, sequencing and host, the pathogen was identified as B. exigua var. heteromorpha. This is thought to be the first report of B. exigua var. heteromorpha on N. oleander causing leaf spot and dieback on oleander in the UK. Following this first report, other cases were confirmed in West Midlands and Berkshire counties. This disease is known previously where Nerium is grown, including France, Italy, Spain and USA.