First report of Paraconiothyrium fuckelii (Didymosphaeriaceae, Pleosporales), causing stem canker in Rosa hybrida, from Iran

摘要

In spring 2016, stem canker symptoms were observed on most Rosa hybrida plants in greenhouses of Kermanshah Province in Western Iran. Initial symptoms of the disease were brown necrotic lesions, mostly 8-10 mm long, on stems. The lesions eventually depressed and expanded to a long ellipse, resulting in yellowing and wilting of the foliage. Fungal colonies resembling those of Paraconiothyrium species were obtained from diseased tissues. Based on morphological and DNA sequence analysis of the internaltranscribed spacers ITS1 and ITS2 and the 5.8S gene the fungal isolates were identified as Paraconiothyrium fuckelii. This is the first report of stem canker disease caused by this species in Iran.Pathogenicity tests were carried out on potted Rosa hybrida plants and detached branches under controlled conditions. Pathogenicity tests demonstrated that the fungus is able to infect and cause canker symptoms on inoculated branches of healthy plants after four weeks. The pathogen was re-isolated from all inoculated plants after observation of the symptoms, thus meeting Koch's postulates.