Mango is an economically important fruit crop in southern China. However, leaf spots restrict the development of mango trees, reducing the yield and production. Pestalotioid fungi are one of the major agents causing leaf spots on mango. During 2016 and 2017, 21 isolates of pestalotioid fungi associated with leaf spots on mango leaves were collected from five provinces in southern China: Guangxi, Hainan, Yunnan, Guangdong, and Fujian. All 21 isolates were subjected to morphological characterization and DNA sequence analysis. The morphological data were combined with analyses of concatenated sequences of the ITS (internal transcribed spacer), TEF 1-α (translation elongation factor), and TUB2 (β-tubulin) for higher resolution of the species identity of these isolates. The results showed that these isolates belong to Neopestalotiopsis clavispora, Pestalotiopsis adusta, P. anacardiacearum, P. asiatica, P. photinicola, P. saprophyta, P. trachicarpicola, and Pseudopestalotiopsis ampullacea. Pathogenicity test results showed that all these species could cause symptoms. On detached mango leaves (cv. Tainong), early foliar symptoms on leaves were small yellow-to-brown lesions. Later, these spots expanded with uneven borders, turned white to gray, and coalesced to form larger gray patches. To our knowledge, this is the first description of N. clavispora, P. adusta, P. asiatica, P. photinicola, P. saprophyta, P. trachicarpicola, or Ps. ampullacea as causal agents for leaf spots on mango worldwide.

Persimmon (Diospyros kaki Thunb.) is widely cultivated in China. On October 15, 2019, about 10% of persimmon fruits showed fruit rot in the orchards of Guilin, Guangxi, China (24°45′ N, 110°24′ E),...

Plum (Prunus salicina Lindl.) is widely cultivated for its rich nutrients and flavor in China. In August 2020, leaf blight symptoms were observed on plum in Meishan, Sichuan, China (N29°24', E104°30'). Irregular brown spots initially appeared on the edge or tip of the leaf, then extended to larger taupe lesions that were surrounded by a chlorotic halo. In the late stage, grey-brown blighted tissue covered the entire leaf causing leaves to wither, curl and abscise. The leaves with blight were collected from three different towns in Meishan where the disease incidence was found on 15-30% of plum plants. The margin of diseased leaves was cut into small pieces (3×3 mm), surface disinfected with 75% ethanol solution for 10 s, 2% NaOCl for 1 min, and rinsed in sterile distilled water three times. Tissue pieces were plated on potato dextrose agar (PDA) and incubated at 25°C. Forty-nine morphologically similar colonies were observed on PDA plates after 3-5 days and three of these (TEY9-1, TEY12-1, TEY15A-1) were selected for intensive study. The colonies produced abundant whitish to yellowish aerial mycelium after 7 days incubation at 25°C in the dark. Macroconidia on carnation leaf agar (CLA) were falcate, hyaline, straight to slightly curved, smooth to slightly rough with 3 to 6 septa, the apical cell was blunt or hooked, and the basal cell was barely notched, 31.6 ± 2.4 μm × 4.7 ± 0.4 μm, 28.9 ± 3.0 μm × 4.5 ± 0.5 μm, 32.5 ± 3.4 μm × 4.5 ± 0.5 for TEY9-1, TEY12-1, TEY15A-1, respectively. Microconidia were hyaline, fusoid or ovoid, nonseptate or one-septate, 14.4 ± 3.9 μm × 4.3 ± 0.6 μm, 13.0 ± 3.0 μm × 4.0 ± 0.4 μm, 11.0 ± 2.4 μm × 3.7 ± 0.5 for TEY9-1, TEY12-1, TEY15A-1, respectively. Genomic DNA was extracted from 7-day-old aerial mycelia of these isolates. The internal transcribed spacer (ITS), translation elongation factor (TEF1), calmodulin (CAM) and partial RNA polymerase second largest subunit (RPB2) were amplified using primers ITS4/ITS1, EF1/EF2, CL1/CL2A, and 5f2/7cr, respectively (White et al. 1990; O'Donnell et al. 2000, 2010). Sequences were deposited in GenBank (ITS: OK315638-OK315640; TEF1: OK338756-OK338758; CAM: OK338759-OK338761; RPB2: OK338762-OK338764). A maximum Likelihood (ML) phylogenetic tree was constructed with RAxML version 8.2.10 based on the concatenated sequences (ITS, TEF1, CAM, RPB2). According to morphology and phylogenetic analysis, TEY9-1 and TEY15A-1 were identified as Fusarium pernambucanum, and TEY12-1 was identified as Fusarium sulawesiense. Pathogenicity tests were conducted on young healthy leaves of 12 two-year-old plum plants in a 28°C greenhouse in Nanning, Guangxi, China. The epidermis of tested leaves was slightly scratched with sterile toothpick-tips forming a 3-mm-diameter cross-shaped wound, followed by inoculation with a 10 μl conidial suspension (106 spores /ml in 0.1% sterile Tween 20). Control leaves were wounded in the same way and treated with 0.1% sterile Tween 20. Plants were covered with polythene bags to maintain high humidity for 5 days. Inoculated leaves showed light brown to dark brown lesions, whereas control leaves were symptomless. Both species were re-isolated from symptomatic leaves, completing Koch's postulates. To our knowledge, this is the first report of F. pernambucanum and F. sulawesiense causing leaf blight on plum trees in China. These results will provide valuable information for prevention and management of leaf blight on plum trees.

Papaya (Carica papaya L.) is a rosaceous plant widely grown in China, which is economically important. Anthracnose caused by Colletotrichum sp. is an important postharvest disease, which severely affects the quality of papaya fruits (Liu et al., 2019). During April 2020, some mature papaya fruits with typical anthracnose symptoms were observed in Fusui, Nanning, Guangxi, China with an average of 30% disease incidence (DI) and over 60% DI in some orchards. Initial symptoms of these papayas appeared as watery lesions, which turned dark brown, sunken, with a conidial mass appearing on the lesions under humid and warm conditions. The disease severity varied among fruits, with some showing tiny light brown spots, and some ripe fruits presenting brownish, rounded, necrotic and depressed lesions over part of their surface. Samples from two papaya plantations (107.54°E, 22.38°N) were collected, and brought to the laboratory. Symptomatic diseased tissues were cut into 5 × 5 mm pieces, surface sterilized with 2% (v/v) sodium hypochlorite for 1 minute, and rinsed three times with sterilized water. The pieces were then placed on potato dextrose agar (PDA). After incubation at 25°C in the dark for one week, colonies with uniform morphology were obtained. The aerial mycelium on PDA was white on top side, and concentric rings of salmon acervuli on the underside. A gelatinous layer of spores was observed on part of PDA plates after 7 days at 28°C. The conidia were elliptical, aseptate and hyaline (Zhang et al., 2020). The length and width of 60 conidia were measured for each of the two representative isolates, MG2-1 and MG3-1, and these averaged 13.10 × 5.11 μm and 14.45 × 5.95 μm. DNA was extracted from mycelia of these two isolates with the DNA secure Plant Kit (TIANGEN, Biotech, China). The internal transcribed spacer (ITS), partial actin (ACT), calmodulin (CAL), chitin synthase (CHS), β-tubulin 2 (TUB2) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) regions were amplified by PCR and sequenced. The sequences were deposited into GenBank with accessions MT904003, MT904004, and MT898650 to MT898659. BLASTN analyses against the GenBank database showed that they all had over 99% identity to the type strain of Colletotrichum siamense isolate ICMP 18642 (GenBank accession numbers JX010278, GQ856775, JX009709, GQ856730, JX010410, JX010019) (Weir et al., 2012). A phylogenetic tree based on the combined ITS, ACT, CAL, CHS, TUB2 and GAPDH sequences using the Neighbor-joining algorithm also showed that the isolates were C. siamense. Pathogenicity tests were conducted on 24 mature, healthy and surface-sterilized papaya fruits. On 12 papaya fruits, three well separated wounded sites were made for inoculation, and for each wounded site, six adjacent pinhole wounds were made in a 5-mm-diameter circular area using a sterilized needle. A 10 µl aliquot of 1 × 106 conidia/ml suspension of each of the isolates (MG2-1 and MG3-1) was inoculated into each wound. For each isolate, there were six replicate fruits. The control fruits were inoculated with sterile distilled water. The same inoculation was applied to 12 non-wound papaya fruits. Fruits were then placed in boxes which were first washed with 75% alcohol and lined with autoclaved filter paper moistened with sterilized distilled water to maintain high humidity. The boxes were then sealed and incubated at 28°C. After 10 days, all the inoculated fruits showed symptoms, while the fruits that were mock inoculated were without symptoms. Koch's postulates were fulfilled by re-isolation of C. siamense from diseased fruits. To our knowledge, this is the first report of C. siamense causing anthracnose of papaya in China. This finding will enable better control of anthracnose disease caused by C. siamense on papaya.

Pearl plum (Prunus salicina Lindl.) is mainly cultivated in Tian’e County in Guangxi Province, southern China. Anthracnose is a devastating disease on pearl plum, causing extensive leaf blight. Diseased leaves were sampled from 21 orchards in Tian’e County. Isolates were first screened for ones resembling Colletotrichum, and 21 representative isolates were selected for sequencing of portions of the ribosomal internal transcribed spacer (ITS), the intergenic region of apn2 and MAT1-2-1 genes (ApMAT), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), chitin synthase (CHS-1), and β-tubulin 2 (TUB2). Based on colony, conidial, and appressorial morphology and sequence analyses, the Colletotrichum isolates associated with pearl plum anthracnose were identified as four species: Colletotrichum fructicola (16 isolates), C. gloeosporioides (3 isolates), C. cigarro (1 isolate), and C. siamense (1 isolate). The results of pathogenicity tests showed that isolates of all four species were pathogenic to wounded leaves of pearl plum seedlings. In this study, we microscopically observed the infection processes of isolates of these four species on attached pearl plum leaves. For C. cigarro and C. siamense, the entire infection processes took 120 h; for C. fructicola and C. gloeosporioides, it only took 72 h. This is the first report of C. fructicola and C. cigarro causing anthracnose on pearl plum worldwide, and also the first report of C. siamense causing anthracnose on pearl plum in China.

Alocasia macrorrhiza (L.) Schott, known as Alocasia is found in the Araceae, and is widely planted in southern China for its ornamental and medicinal value. This plant has a wide range of pharmacol...