First Report of Colletotrichum gloeosporioides causing anthracnose on Elaeocarpus sylvestris in Sichuan Province of China.

Elaeocarpus sylvestris (Lour.) Poir is a cultivated evergreen tree commonly used in landscape plantings. In October 2012, lesions were found on young and mature leaves at Ya’an and Chengdu in Sichuan Province, China, according to our investigation. The disease symptoms began as discrete, yellow-green spots, and then coalesced into larger lesions. The centers of the lesions were light brown and borders were deep red. Rain caused lesions to swell, then decay and perforate, and dry conditions caused lesion centers to crack. Lesions were scattered on abaxial and adaxial leaf surfaces and contained brown to black acervuli. Multiple trees were infected with this disease, and approximately 3 to 5% of leaves were harmed. The disease caused unsightly defoliation, and weakening of the tree. To isolate the fungus, pieces of symptomatic tissues were surface sterilized for 1 min in 75% ethanol, rinsed three times in sterile water and plated on potato dextrose agar (PDA) and incubated at 25 ± 2°C. Many similar-looking colonies of fast-growing mycelium were isolated from all samples. To fulfill Koch’s postulates, a conidial suspension (5 × 106 conidia per ml) collected from isolate DY1 (a representative isolate, collected from Ya’an in 2013) was sprayed onto 10 young leaves of E. sylvestris. Distilled water was used as a control and sprayed onto an equal number of young leaves. Inoculated and control leaves were incubated in separate humidity boxes, then placed in growth chambers at 25± 2°C with a 12-h photoperiod. Isolate DY1 caused symptoms similar to those observed under field conditions within 7 days, and no symptoms were observed on control leaves. For identification, the pure cultures of DY1 were obtained using the single-spore method and cultured on PDA. The mycelium covered the entire plate surface (9 cm diameter) after 5 days of growth at 25 ± 2°C in the dark. Hyphae were white at first, becoming dark with age. After 7 days, colonies showed abundant aerial, pale-gray to gray mycelium with pink conidial masses. The conidia were one-celled, cylindrical, hyaline, rounded at both ends and ranged from 8.3 to 23.5 μm long (mean 14.7 μm) × 3.1 to 7.7 μm wide (mean 5.8 μm) (n = 100). Based on morphological and cultural characteristics, isolates were identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (Sutton 1980.). Further comparisons were completed with one pure culture of DY1 by PCR and BLAST sequencing analyses of the partial ITS rDNA region, actin, β-tubulin, GAPDH, calmodulin, CHS-1, and glutamine synthetase genes (Weir et al. 2012). (GenBank Accession Nos. KR264868, KR264869, KR264870, KR264871, KR264872, KR264873, and KR264874, respectively). The results showed high identity of all the 7 sequences to the ex-epitype culture of C. gloeosporioides (Penz.) Penz. & Sacc. (IMI 356878, Accession Nos. JX010152 in ITS = 99%, JX009531.1 in actin = 99%, JX010445 in β-tubulin = 99%, JX010056 in GAPDH = 99%, JX009731 in calmodulin = 100%, JX009818 in CHS-1 = 100%, and JX010085 in glutamine synthetase genes = 98%). To our knowledge, there are no previous reports of C. gloeosporioides causing anthracnose of this important landscape tree. The findings make it clear the pathogen is causing anthracnose on E.sylvestris in Sichuan Province, China, and provide a basis for the diagnosis and treatment of the disease. © 2016 The American Phytopathological Society.