Sharma, G., Department of Plant Pathology and Weed Research, ARO, The Volcani Center, Bet Dagan, Israel
Maymon, M., Department of Plant Pathology and Weed Research, ARO, The Volcani Center, Bet Dagan, Israel
Freeman, S., Department of Plant Pathology and Weed Research, ARO, The Volcani Center, Bet Dagan, Israel

Avocado (Persea americana) is widely cultivated throughout Israel, with the coastal plain and eastern valleys of Upper Galilee comprising the major growing areas (Dor 2015). During sample collection of unripe avocado fruits (cv. Hass) from northern and central Israel in November 2014, profuse salmon-colored sporulation was observed on the skins of fruits during the ripening process. A fungal pathogen was isolated from the infected fruits and four single-spored isolates were selected for further characterization. The isolates produced white mycelium with rosy-pink sporulation. Conidia were hyaline, two-celled, ellipsoid to pyriform with a narrow truncated base, measuring 8 to 15 × 4 to 6 μm in size, produced in basipetal chains as clusters. DNA sequencing of the 5.8S rRNA gene and the flanking internal transcribed spacer regions (ITS) was conducted using ITS 4 and 5 primer set, for four isolates (X1 to X4; GenBank Accession Numbers ITS: KT359586 to KT359589, respectively). Maximum likelihood analysis was conducted using MEGA v6.06, and compared with reference sequences taken from NCBI (Summerbell et al. 2011); all the isolates clustered within the Trichothecium roseum clade. Based on morphological characteristics and phylogenetic analysis, the four isolates were identified as T. roseum. Pathogenicity testing was performed in triplicate simultaneously (cv. Hass, three fruits per replicate). Each avocado fruit was surface sterilized using 1% NaOCl, and 10 µl of conidial suspension (1 × 107 spore/ml) was inoculated at one wounded (pin-pricked) and unwounded site, respectively. Control fruits were mock-inoculated with 10 µl of sterile water. All the fruits were kept in a moist chamber at 25°C. Fruits inoculated with the conidial suspensions of all four isolates developed typical pink sporulation followed by soft-rot lesions after 5 days of incubation for each isolate in the wounded and unwounded treatments. No symptoms were observed in the control, even after 10 days. To validate Koch’s postulates, T. roseum was reisolated from the infected fruits and verified by morphological analysis. Trichothecium roseum is well known as an opportunistic wound pathogen of avocado (Barkai-Golan et al. 2002), and thus far, pink rot disease in avocado has been reported only in New Zealand (Farr and Rossman 2015). Although T. roseum has previously been observed along with other avocado pathogens such as Botryosphaeria spp. and Colletotrichum spp. in Israel (Barkai-Golan et al. 2002), the original occurrence of T. roseum was saprophytic and/or opportunistic. To the best of our knowledge, this is the first detailed report of T. roseum causing postharvest pink rot of avocado in this country. © 2016, American Phytopathological Society. All rights reserved.