Loquat, Eriobotrya japonica (Thunb.) Lindl., is an important fruit that is widely planted and used as an ornamental in Jingxian, Anhui Province, China. Loquat branches with severely spotted leaves and fruits were observed in this region in 2012. Symptoms on leaves consisted of small (0.5 to 1.2 cm in diameter), circular to oblong, greenish-brown lesions that coalesced to form isolated or confluent, dark brown spots. On fruit, the disease appeared as circular to elongated, sunken spots. Expanding lesions spread over the surface resulting in death of the fruit. Acervuli were observed within lesions. Isolations from symptomatic tissue onto potato dextrose agar (PDA) medium consistently yielded white fungal colonies of sparse aerial mycelium with acervuli containing black, slimy spore masses on the surface. The colony reached 8.0 cm diameter after 7-day culture on PDA at 24°C. Conidia produced in the culture were five-celled, narrow fusiform, straight or slightly curved, with a tapering base and 2 to 4 hyaline appentages (apical appentages measured 15 to 34 μm long and a single basal appentage was 5 to 9 μm long). Conidia were 24 to 32 × 5 to 8 μm with median cells 15 to 20 μm and two hyaline, cylindrical to conical apical cells typical of Pestalotiopsis spp. (3). A total of 12 isolates were obtained by isolation from the diseased fruit or leaves. Genomic DNA from the fungal isolates was purified using a DNA Gel Extraction Kit (AxyPrep, Hangzhou, China), and applied to a DNA Engine System PTC-200 (BIO-RAD, Watertown, MA) with ITS1 and ITS4 internal transcribed spacer (ITS) universal primers. The amplified sequences (533 bp) were analyzed together with other Pestalotiopsis sequences (1). ITS from all 12 of the fungal isolates were identical (99.5% similarity) to each other and to isolates of Pestalotiopsis theae, which infects tea trees in China (2). To demonstrate pathogenicity, suspensions (prepared in distilled water) of 106 conidia ml–1 of each isolate were sprayed on the loquat leaves in vivo and mature fruits in vitro. Distilled water was used as the control. More than 20 leaves and 10 mature fruits were sprayed for the treated and control plants, respectively, and the inoculation tests were repeated twice. The inoculated plants and fruit were kept in a humidity chamber for 7 days. Approximately 50% of the inoculated leaves and fruits developed blight symptoms similar to natural infections. P. theae was reisolated from diseased plants to complete Koch's postulates. Control plants sprayed with distilled water remained symptomless. There is a previous study reporting that P. guepini infected loquat in Argentina (4); however, to our knowledge, this is the first report of P. theae causing leaf and fruit spots on loquat in China.
References: (1) R. Jeewon et al. Mol. Phylogenet. Evol. 25:378, 2002. (2) J. Y. Lu. Diagnosis of plant diseases. Page 194 in: Pestalotiopsis. J. Y. Lu, Z. G. Xu, Y. X. Chen, D. R. Shen, X. B. Zheng, and Y. Q. Cao, eds. China Agriculture Press, Beijing, 1995. (3) T. R. Nag Raj. Coelomycetous Anamorphs with Appendage-Bearing Conidia. Mycologue Publications, Waterloo, Canada, 1993. (4) A. E. Perelló and S. Larran. Plant Dis. 83:695, 1999.