First report of Paraconiothyrium fuckelii (Didymosphaeriaceae, Pleosporales), causing stem canker in Rosa hybrida, from Iran SAMAD JAMALI Department of Plant Protection, College of Agriculture, Razi University, Kermanshah, IR-67156-85435, Iran; jamali454@yahoo.com Jamali S. (2020): First report of Paraconiothyrium fuckelii (Didymosphaeriaceae, Pleosporales), causing stem canker of Rosa hybrida, from Iran. – Czech Mycol. 72(1): 71–82. In spring 2016, stem canker symptoms were observed on most Rosa hybrida plants in green- houses of Kermanshah Province in Western Iran. Initial symptoms of the disease were brown ne- crotic 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 internal transcribed spacers ITS1 and ITS2 and the 5.8S gene the fungal iso- lates 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 un- der 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. Key words: Dothideomycetes, fungal disease, internal transcribed spacers, Iran mycobiota, patho- genicity. Article history: received 10 October 2019, revised 21 March 2020, accepted 4 May 2020, published online 29 May 2020. DOI: https://doi.org/10.33585/cmy.72105 Jamali S. (2020): První nález Paraconiothyrium fuckelii (Didymosphaeriaceae, Pleosporales), původce stonkové nekrózy růží, v Íránu. – Czech Mycol. 72(1): 71–82. Na jaře 2016 byly pozorovány nekrotické symptomy na stoncích růží ve sklenících v provincii Kermanšah v západním Íránu. Prvotními symptomy napadení byly hnědé, 8–10 mm dlouhé nekrotic- ké léze na stoncích; ty se časem prohlubovaly a rozšiřovaly do tvaru dlouhé elipsy, přičemž docházelo k žloutnutí a vadnutí listů. Z napadených pletiv byly získány kolonie připomínající druhy rodu Para- coniothyrium. Na základě morfologického studia a anylýzy sekvencí ITS1, ITS2 a 5.8S byly izoláty určeny jako Paraconiothyrium fuckelii. Jde o první záznam o výskytu tohoto druhu coby původce stonkové nekrózy v Íránu. 71 CZECH MYCOLOGY 72(1): 71–82, MAY 29, 2020 (ONLINE VERSION, ISSN 1805-1421)