Cylindrocladiella peruviana and Pleiocarpon algeriense causing stem and crown rot on avocado ( Persea americana )
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Cylindrocladiella peruviana and Pleiocarpon algeriense causing stem and crown rot on avocado (Persea americana) Dalia Aiello & Giorgio Gusella & Alessandro Vitale & Vladimiro Guarnaccia & Giancarlo Polizzi
Accepted: 21 July 2020 # The Author(s) 2020
Abstract During the winter of 2018, 3-years-old trees of avocado (Persea americana) cv “Hass” from Trapani province (Sicily, Italy) showed symptoms of stem and crown rot. Two different fungi were consistently isolated from infected tissues. Morphological characterization and multi-locus phylogenies using five genomic loci (ITS, tef1, tub2, his3, and rpb2) identified these fungi as Cylindrocladiella peruviana and Pleiocarpon algeriense. Pathogenicity tests on healthy 5-monthsold seedlings and 3-year-old trees of avocado reproduced similar symptoms as those observed in nature, and Koch’s postulates were fulfilled for both pathogens. Moreover, the tested fungal isolates revealed a different pathogenic behaviour among two species. Two isolates of Pleiocarpon algeriense resulted more aggressive than Cylindrocladiella peruviana isolates causing major lesions on young seedlings. This study is the first to report of stem and crown rot on avocado caused by Cylindrocladiella peruviana and Pleiocarpon algeriense.
D. Aiello (*) : G. Gusella : A. Vitale : G. Polizzi Dipartimento di Agricoltura, Alimentazione e Ambiente, sezione Patologia Vegetale, University of Catania, Via S. Sofia 100, 95123 Catania, Italy e-mail: [email protected] V. Guarnaccia DiSAFA, University of Torino, Largo Paolo Braccini, 2, 10095 Grugliasco, TO, Italy
Keywords Fungal diseases . Nectriaceae . Molecular characterization
Introduction Avocado (Persea americana Mill.) is native to Mexico but is spread around the world in tropical and subtropical regions. In southern Italy (Sicily), several farms of different extension coexist, directing their production to local market as well as European market (Migliore et al. 2018). Although the agronomic studies on this crop in Italy started more than 20 years ago, studies on phytopathological aspects have been limited. Recently, a wide study on branch cankers and stem-end rot conducted in the main avocado growing area in eastern Sicily revealed the presence of different species such as Neofusicoccum parvum (the highest virulent), Diaporthe foeniculina (=D. foeniculaceae), D. sterilis, Colletotrichum gloeosporioides, C. fructicola, and a novel species Neocosmospora perseae (Guarnaccia et al. 2016, 2018). These reports show how woody cankers and stem-end rot could be considered the most important threats for avocado production in Italy so far. Avocado symptoms at the rhizosphere such as rot, discolouration, sunken lesions, and subsequent aspecific symptoms of the canopy such as wilt, leaves chlorosis/ browning, and decline, have been studied worldwide. These studies showed how several species within the Nectriaceae (Hypocreales, Ascomycetes) are involved in what is defined “Black root rot disease” (Dann et al. 2011, 2012; Parkinson et al. 2017a, b). A recent resear
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