Cherry is widely planted in China, from Liaoning, Beijing, Hebei, Shandong, Zhejiang, Jiangsu, and Anhui provinces (eastern China), to Shaanxi, Sichuan, Chongqing, and Guizhou provinces (western China). The brown rot fungus Monilinia fructigena causes considerable production losses in cherry production in Liaoning Province (3). In May 2013, Chinese sour cherry (Prunus pseudocerasus) cv. Wupi displaying symptoms of brown rot was found in an orchard in Chongqing municipality. Diseased cherry fruit had a brown rot sporulating with grayish, conidial tufts. The fruit later succumbed to the soft rot or shivered and became a mummy. Single-spore isolations on PDA resulted in colonies with concentric rings of pigmented mycelium with lobbed margins. Conidia were broadly ellipsoid to subglobose, occasionally even globose, with an average size of 16 × 12.7 μm. Multiple germ tubes were produced from each conidium, a germination pattern unique to Monilia mumecola (1,2,4). The pathogen identity was confirmed by multiplex PCR as described by Hu et al. (2). The PCR resulted in a 712-bp amplicon, which is diagnostic of M. mumecola. Further sequencing of the internal transcribed spacer (ITS) region 1 and 2 and 5.8S gene further indicated 100% identity with that of M. mumecola isolates from China (Accession No. HQ908786) and from Japan (AB125613, AB125614, and AB125620). Koch's postulates were confirmed by inoculating mature cherry fruit with mycelia plugs. Inoculated fruit were placed in a sterilized moist chamber, and incubated at 22°C with 12 h light/dark cycle. Inoculated fruit developed typical brown rot symptoms only 2 days after inoculation, while the control fruit, inoculated with a sterile PDA plug, remained healthy. The pathogen isolated from inoculated symptomatic fruit was confirmed to be M. mumecola based on morphological characteristics and germination pattern. It should be noted that the conidia on inoculated fruit showed an average size of 20 × 15.3 μm, significantly bigger than that of from PDA, and most produced more than three germ tubes. The inoculation experiments were performed in triplicates. M. mumecola was first reported as the causal agent of brown rot of mume in Japan in 2004 (1). Later studies demonstrated that it is also pathogen on other stone fruits, e.g., peach, nectarine (2), and apricot (4). To our knowledge, this is the first report of cherry brown fruit rot caused by M. mumecola, and the first report of M. mumecola in Chongqing municipality.
References: (1) Y. Harada et al. J. Gen. Plant Pathol. 70:297, 2004. (2) M. J. Hu et al. Plos One 6(9): e24990, 2011. (3) Z. H. Liu et al. J. Fruit Sci. 29:423, 2012. (4) L. F. Yin et al. Plant Dis. 98:694, 2014.