scholarly journals First Report of Pilidium concavum Causing Tan-Brown Leaf Spot on Strawberry in China

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1377-1377 ◽  
Author(s):  
W. L. Geng ◽  
P. Hu ◽  
Z. Ma ◽  
X. Y. Zhao ◽  
Y. M. Wei
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Leaf Tissue ◽  
Brown Rot ◽  
Pathogenicity Test ◽  
Causal Organism ◽  
First Report ◽  
Molecular Features ◽  
Brown Leaf Spot ◽  
Brown Leaf

In April 2011, a survey of diseases was conducted on strawberry plants grown in greenhouses in the town of Xingshou, Changping District, Beijing, China. A tan-brown leaf spot with the presence of pink spore masses was observed on older leaves of strawberry plants. In general, the leaf spots began as small, round, water-soaked lesions in the middle or on the margin of leaves, which enlarged gradually up to 1 to 3 cm in diameter and were circular or irregular and brown to dark brown. Occasionally, the center of some spots cracked in the middle lesion under dry conditions. Eventually, black sporodochia were produced on the upper surface of spots and exuded pink conidial masses under humid conditions. Fungal structures were taken directly from the diseased leaves and examined microscopically for morphological characteristics. Sporodochia, 172 to 451 × 138 to 343 μm, were dark and suborbicular. Conidiophores, 8.4 to 48.3 × 0.8 to 2.1 μm, were hyaline, unicellular, and cylindrical. Conidia, 3.1 to 10.2 × 1.5 to 3.0 μm, were hyaline, aseptate, and canoe-shaped to allantoid, forming singly. For further study, the fungus was isolated in pure culture on potato dextrose agar (PDA) medium from symptomatic leaf tissue. In culture, the mycelium was white at first and then changed to brownish. The sporodochia were light colored at first and turned brownish or almost black in older cultures. To identify the fungus, the ITS1-5.8S-ITS2 rDNA region of the isolate was amplified by PCR with primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) and sequenced. The 462-nt sequence (GenBank Accession No. JQ995228) was identical to that of Pilidium concavum (1). To validate Koch's postulates, pathogenicity was tested by inoculating 20 leaves on 10 healthy strawberry plants with a mycelial plug from a 15-day-old colony (0.5 cm in diameter). Controls were treated with plugs of PDA medium. The inoculated and control plants were then maintained in growth chambers at 25°C (12 h of light per day, 80% humidity). After 12 days, 100% of the inoculated leaves showed symptoms identical to those observed on leaves in the field while the control leaves remained healthy. The original fungus was reisolated from inoculated leaves showing the symptoms. Thus, it was concluded that the fungus was the causal organism of the leaf spot. On the basis of morphological characteristics, molecular features, and pathogenicity tests, the pathogen of tan-brown leaf spot on strawberry was identified as P. concavum. To our knowledge, this is the first report of P. concavum causing tan-brown leaf spot on strawberry in China. This fungus was reported to cause leaf spot on Paeonia suffruticosa in China (2). It also caused tan-brown rot on strawberry fruit in our pathogenicity test. References: (1) L. Cardin et al. Plant Dis. 93:548, 2009. (2) Y. B. Duan et al. Plant Dis. 94:271, 2010.

scholarly journals Brown leaf spot of Cycas debaoensis Caused by Colletotrichum siamense in Sichuan, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shan Han ◽  
Jimin Ma ◽  
Yanyue Li ◽  
Shujiang Li ◽  
yinggao Liu ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Negative Control ◽  
Wild Plants ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Potted Plants ◽  
Brown Leaf Spot ◽  
Brown Leaf

Cycas debaoensis Y. C. Zhong et C. J. Chen is an endemic species in China that is listed among China’s national key preserved wild plants (Class I) (Xie et al. 2005). It is mainly distributed in south China (Guangxi, Guizhou, and other regions). In April 2017, a new leaf disease of C. debaoensis was found in Chengdu (30°35′32″ N; 104°05′11″E) in China with an incidence over 40%. Symptoms on C. debaoensis initially appeared as brown necrotic lesions on the margin or in the center of leaves. The lesions then enlarged gradually and developed into brown spots, necrotic lesions with dark brown margins. Many small and black dots were observed on necrotic lesions. Eventually, the diseased leaves withered and died. Ten samples were collected and surface-sterilized by 3% NaClO and 75% ehanol respectively for 60s and 90s, rinsed with autoclaved distilled water and then blot-dried with autoclaved paper towels. Five isolates from diseased leaves with similar morphology were isolated from single spores. Morphological characteristics were recorded from pure cultures grown on potato dextrose agar (PDA) incubated at 25°C for 3-9 days. Initially, the colonies grown on PDA were white, then, became pale gray with concentric zones and greenish black beneath. Conidia were single-celled, smooth-walled, straight, colorless, cylindrical with both ends bluntly rounded,13.0-16.5 × 4.7-5.8 μm in size (n = 100 spores). For molecular identification, the genomic DNA of the isolates was extracted using a DNeasyTM Plant Mini Kit (Qiagen). The internal transcribed spacer (ITS) (ITS1/ITS4 White et al., 1990), β-tubulin (TUB2) (BT2A/BT2B (O’Donnell et al., 1997)), actin (ACT) (ACT512F/ACT (Carbone & Kohn, 1999)), calmodulin (CAL) (CL1C/CL2C (Weir et al., 2012)), mating type protein and chitin synthase (CHS-1) (CHS-1) (CHS-9 79F/CHS-345R (Carbone & Kohn, 1999)) were amplified. BLAST results indicated that the ITS, TUB2, ACT, CAL, CHS-1 sequences (GenBank MN305712, MN605072, MT478663, MT465591 and MT478664) showed 99-100% identity with C. siamense sequences at NCBI (GenBank JF710564, MK341542, MK855094, MH351155 and MK471373). The Phylogenetic tree inferred from the combined dataesets (TEF, TUB and ACT) show that the isolate belongs to C. siamense clade with a credibility value of 99%. Two-year-old potted plants of C. debaoensis (10 plants) were used for pathogenicity test. On each plant, 5 leaves were sprayed with a conidial suspension (1 × 106 conidia/ml) on both sides of the leaves. Autoclaved distilled water was used as negative control (10 plants). Plants were kept in the greenhouse at 25 °C under 16h/8h photoperiod and 70-75% relative humidity (RH). The symptoms observed on the inoculated plants were similar to those observed in the field, while the controls remained asymptomatic. C. siamense was re-isolated from all diseased inoculated plants, and the culture and fungus characteristics were the same as the original isolate. The morphological characteristics and molecular analyses of the isolate matched the description of C. siamense (Prihastuti et al., 2009). C. siamense was previously reported infecting Citrus reticulata (Cheng et al. 2013), but this is the first report of brown leaf spot on C. debaoensis caused by C. siamense in China. This finding provides important basis for further research on the control of the disease.

scholarly journals First Report of Brown Leaf Spot of Juglans hybrid Caused by Ophiognomonia leptostyla in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Chunlin Yang ◽  
Feng Liu ◽  
Qian Zeng ◽  
Xiulan Xu ◽  
Yicong Lv ◽  
...  
Keyword(s):  
Basal Cell ◽  
Leaf Spot ◽  
Juglans Regia ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Effective Control ◽  
First Report ◽  
Brown Leaf Spot ◽  
Brown Leaf

“Chuanzao 2” is a walnut variety derived from the hybridization of Juglans regia L. and J. sigillata Dode distributed in southwest China, where it is an economically important tree species in rural regions (Xiao et al. 2012). In April 2020, the variety in a walnut garden showed symptoms of brown leaf spot in Beishan Town (107°21′43.93″E, 31°28′12.34″N), Dazhou City in Sichuan, China, with 5% to 10% of leaves per plant affected (5 plants). Symptomatic leaves showed brown to dark brown spots (2 to 5 mm) with a dark brown to black halo and grayish-tan center. The spots were subcircular to irregular in shape, and gradually expanded and formed necrotic spots. A single conidium isolation was performed (Senanayake et al. 2020) and transferred to Potato Dextrose Agar (PDA). Five isolates were obtained from five different infected leaves. Colonies of five isolates were subcircular, erose or dentate, flat or effuse, white initially, gradually becoming yellowish with white margins, developed and fluffy aerial mycelia, and conidiogenensis was produced underneath mycelia after 25-days-incubation. Conidiogenous cells were subcylindrical to cylindrical, or irregular in shape, and hyaline. Macroconidia were lunate, reniform, hyaline, basal cell bluntly rounded, apical cell with acute end, 1-septate, rarely aseptate, sometimes slightly constricted at septum, basal cell equal or larger than apical cell, and measured 16.5 to 30.5 × 5 to 8.5 μm (mean = 23.2 × 6.3 μm, n = 50). Microconidia were not observed. These morphological characteristics resembled those of Ophiognomonia leptostyla (Fr.) Sogonov (Walker et al. 2012a). For molecular identification, genomic DNA (isolates SICAUCC 21-0008 and SICAUCC 21-0010) was extracted, and the internal transcribed spacers (ITS) region, guanine nucleotide-binding protein subunit beta (MS204) gene, and translation elongation factor 1-alpha (tef1-α) were amplified and sequenced by using the primers ITS5/ITS4 (White et al. 1990), E1F1/E5R1a (Walker et al. 2012a), and EF1-728F/EF1-1567R (Walker et al. 2012b), respectively. Phylogenetic analyses (maximum likelihood) based on a combined dataset showed 100% bootstrap support values in a clade with O. leptostyla. The sequences of ITS, MS204, and tef1-α genes were deposited in GenBank with accession numbers MW493111/MZ026300, MW495270/MZ031975, and MW495271/MZ031974, respectively. To fulfill Koch’s postulates, five healthy hybrid plants (2 to 3 years old) with 5 to 8 leaves per plant were spray inoculated with conidium suspensions (104 conidia/mL; isolate SICAUCC 21-0008) prepared from 40-days-old cultures onto the wounded sites via pin-prick inoculation. Similarly, five noninoculated plants sprayed with sterile water served as controls. Plants were placed in a growth chamber at 25℃ on a 12-h fluorescent light/dark regime and daily sprayed with sterile distilled water. After two weeks, observed symptoms were similar to those from natural infections. No disease symptoms were found on control plants. The fungus O. leptostyla was reisolated from the diseased leaves and characterized morphologically. O. leptostyla is a global pathogen and has been reported to cause the leaf spot in many walnut trees, viz. J. ailantifolia, J. californica, J. cinerea, and J. major, etc. To our knowledge, this is the first report of O. leptostyla causing brown leaf spot on Juglans hybrid (J. regia × J. sigillata) in China. The increasing risk of this pathogen in the walnut-growing areas of Sichuan Province of China needs a further exploration and outreach effort to develop effective control measures. Chunlin Yang, Feng Liu, and Qian Zeng contributed equally to this paper.

scholarly journals First Report of Ramularia coleosporii causing Leaf Spot on Perilla frutescens in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Md Aktaruzzaman ◽  
Tania Afroz ◽  
Hyo-Won Choi ◽  
Byung Sup Kim
Keyword(s):  
Leaf Spot ◽  
Ipomoea Batatas ◽  
Rust Fungus ◽  
Morphological Characteristics ◽  
Perilla Frutescens ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Perilla (Perilla frutescens var. japonica), a member of the family Labiatae, is an annual herbaceous plant native to Asia. Its fresh leaves are directly consumed and its seeds are used for cooking oil. In July 2018, leaf spots symptoms were observed in an experimental field at Gangneung-Wonju National University, Gangneung, Gangwon province, Korea. Approximately 30% of the perilla plants growing in an area of about 0.1 ha were affected. Small, circular to oval, necrotic spots with yellow borders were scattered across upper leaves. Masses of white spores were observed on the leaf underside. Ten small pieces of tissue were removed from the lesion margins of the lesions, surface disinfected with NaOCl (1% v/v) for 30 s, and then rinsed three times with distilled water for 60 s. The tissue pieces were then placed on potato dextrose agar (PDA) and incubated at 25°C for 7 days. Five single spore isolates were obtained and cultured on PDA. The fungus was slow-growing and produced 30-50 mm diameter, whitish colonies on PDA when incubated at 25ºC for 15 days. Conidia (n= 50) ranged from 5.5 to 21.3 × 3.5 to 5.8 μm, were catenate, in simple or branched chains, ellipsoid-ovoid, fusiform, and old conidia sometimes had 1 to 3 conspicuous hila. Conidiophores (n= 10) were 21.3 to 125.8 × 1.3 to 3.6 μm in size, unbranched, straight or flexuous, and hyaline. The morphological characteristics of five isolates were similar. Morphological characteristics were consistent with those described for Ramularia coleosporii (Braun, 1998). Two representative isolates (PLS 001 & PLS003) were deposited in the Korean Agricultural Culture Collection (KACC48670 & KACC 48671). For molecular identification, a multi-locus sequence analysis was conducted. The internal transcribed spacer (ITS) regions of the rDNA, partial actin (ACT) gene and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene were amplified using primer sets ITS1/4, ACT-512F/ACT-783R and gpd1/gpd2, respectively (Videira et al. 2016). Sequences obtained from each of the three loci for isolate PLS001 and PLS003 were deposited in GenBank with accession numbers MH974744, MW470869 (ITS); MW470867, MW470870 (ACT); and MW470868, MW470871 (GAPDH), respectively. Sequences for all three genes exhibited 100% identity with R. coleosporii, GenBank accession nos. GU214692 (ITS), KX287643 (ACT), and 288200 (GAPDH) for both isolates. A multi-locus phylogenetic tree, constructed by the neighbor-joining method with closely related reference sequences downloaded from the GenBank database and these two isolates demonstrated alignment with R. coleosporii. To confirm pathogenicity, 150 mL of a conidial suspension (2 × 105 spores per mL) was sprayed on five, 45 days old perilla plants. An additional five plants, to serve as controls, were sprayed with sterile water. All plants were placed in a humidity chamber (>90% relative humidity) at 25°C for 48 h after inoculation and then placed in a greenhouse at 22/28°C (night/day). After 15 days leaf spot symptoms, similar to the original symptoms, developed on the leaves of the inoculated plants, whereas the control plants remained symptomless. The pathogenicity test was repeated twice with similar results. A fungus was re-isolated from the leaf lesions on the inoculated plants which exhibited the same morphological characteristics as the original isolates, fulfilling Koch’s postulates. R. coleosporii has been reported as a hyperparasite on the rust fungus Coleosporium plumeriae in India & Thailand and also as a pathogen infecting leaves of Campanula rapunculoides in Armenia, Clematis gouriana in Taiwan, Ipomoea batatas in Puerto Rico, and Perilla frutescens var. acuta in China (Baiswar et al. 2015; Farr and Rossman 2021). To the best of our knowledge, this is the first report of R. coleosporii causing leaf spot on P. frutescens var. japonica in Korea. This disease poses a threat to production and management strategies to minimize leaf spot should be developed.

scholarly journals Characterization of Pyrenophora Species Causing Brown Leaf Spot on Italian Ryegrass (Lolium multiflorum) in Southwestern China

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1900-1907
Author(s):  
Longhai Xue ◽  
Yong Liu ◽  
Su Zhou ◽  
James F. White ◽  
Chunjie Li
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Lolium Multiflorum ◽  
Morphological Characteristics ◽  
Italian Ryegrass ◽  
Large Area ◽  
Internal Transcribed Spacer Region ◽  
Brown Leaf Spot ◽  
Brown Leaf ◽  
Pathogenicity Tests

Drechslera leaf spot (DLS) caused by Pyrenophora (Drechslera) species is one of the most serious diseases affecting Italian ryegrass (Lolium multiflorum) in China. Between 2015 and 2018, this disease was observed in three Italian ryegrass fields in the province of Sichuan, China. Average leaf disease incidence was approximately 1 to 12% but could range up to 100%. Symptoms appeared as brown or tan spots surrounded by a yellow halo, or brown to dark brown net blotch; subsequently, spots increased in number and size, and they later covered a large area of leaf, eventually causing leaf death. In this study, 86 strains of Pyrenophora fungi were isolated from leaf lesions of Italian ryegrass. Coupled with phylogenetic analysis of the internal transcribed spacer region, partial 28S ribosomal RNA gene, and glyceraldehyde-3-phosphate dehydrogenase gene, morphological characteristics showed that Pyrenophora dictyoides and P. nobleae are associated with Italian ryegrass in southwest China. Pathogenicity tests confirmed that both species can infect Italian ryegrass, causing leaf spot, whereas the virulence of the two species differed; P. nobleae showed lower pathogenicity to Italian ryegrass. This is the first time that these two Pyrenophora species were formally reported on Italian ryegrass based on both morphological and molecular characters. Overall, this study improves knowledge of the Pyrenophora species associated with Italian ryegrass and provides a foundation for control of this disease in the future.

scholarly journals First report of Nigrospora oryzae causing brown leaf spot on Mentha spicata

2020 ◽  
Vol 102 (4) ◽  
pp. 1281-1281
Author(s):  
Khadijeh Farid ◽  
Doustmorad Zafari ◽  
Mohammad Javad Soleimani ◽  
Shima Bagherabadi
Keyword(s):  
Leaf Spot ◽  
Mentha Spicata ◽  
First Report ◽  
Brown Leaf Spot ◽  
Brown Leaf ◽  
Nigrospora Oryzae

scholarly journals Morphology and Molecular Characteristics of Alternaria sonchi Causing Brown Leaf Spot on Sonchus asper in Korea

2021 ◽  
Vol 27 (3) ◽  
pp. 107-114
Author(s):  
Huan Luo ◽  
Myung Soo Park ◽  
Jun Myoung Yu
Keyword(s):  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Internal Transcribed Spacer Region ◽  
Sonchus Asper ◽  
Brown Leaf Spot ◽  
Brown Leaf

During a disease survey on weeds and minor cultivated crops in Korea, a brown leaf spot disease was observed on Sonchus asper. Leaf lesions were round or irregular in shape, and grayish brown to brown with a purple margin. In severe infection, lesions enlarged and coalesced, resulting in blighting of the leaves. The isolates from these leaf lesions were identified as Alternaira sonchi based on morphological characteristics and phylogenetic analyses of Internal transcribed spacer region, Alternaria allergen a1, glyceraldehyde 3-phosphate dehydrogenase, RNA polymerase II, and translation elongation factor genes. This study provides a comprehensive description of the morphological characteristics and phylogenetical traits of A. sonchi causing brown leaf spot on S. asper in Korea.

scholarly journals First Report of Alternaria Alternata Causing Brown Leaf Spot on Apricot (Prunus Armeniaca) in Karbala Province of Iraq

2021 ◽  
Vol 910 (1) ◽  
pp. 012080
Author(s):  
Zeinab L. Hameed ◽  
Adnan A. Lahuf ◽  
Mundher T. Jasim ◽  
Hassan M. Mohsen ◽  
Bahaa J. Kadim ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Leaf Spot ◽  
Causative Factor ◽  
Prunus Armeniaca ◽  
Leaf Spot Disease ◽  
First Report ◽  
Spot Disease ◽  
Brown Leaf Spot ◽  
Rdna Sequencing ◽  
Brown Leaf

Abstract During a survey in season 018, leaf spot symptoms were commonly observed on apricot (Prunus armeniaca) trees in the orchards of Al-Hussainiya district in Karbala Province of Iraq. The symptomatic leaves were gathered, the associated fungus was isolated and characterized relied on its morphological features and ITS-rDNA sequencing. The causative factor was found to be the fungus Alternaria alternata that caused distinguishable leaf spot symptoms on the inoculated leaves of apricot. Based on a review of previous references relatedof this disease in Iraq, this is the first report of the brown leaf spot disease caused by A. alternata in Karbala province of Iraq.

scholarly journals First report of leaf spot disease caused by Stemphylium eturmiunum on garlic in Korea.

Plant Disease ◽  
2021 ◽  
Author(s):  
Walftor Dumin ◽  
Mi-Jeong Park ◽  
You-Kyoung Han ◽  
Yeong-Seok Bae ◽  
Jong-Han Park ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Allium Sativum ◽  
Morphological Characteristics ◽  
Fungal Isolate ◽  
Causal Agent ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
First Report ◽  
Spot Disease ◽  
Intact Leaves

Garlic (Allium sativum L. cv.namdo) is one of the most popular vegetables grown in Korea due to its high demand from the food industry. However, garlic is susceptible to a wide range of pest infestations and diseases that cause a significant decrease in garlic production, locally and globally (Schwartz and Mohan 2008). In early 2019, the occurrence of leaf blight disease was found spreading in garlic cultivation areas around Jeonnam (34.9671107, 126.4531825) province, Korea. Disease occurrence was estimated to affect 20% of the garlic plants and resulted in up to a 3-5% decrease in its total production. At the early stage of infection, disease symptoms were manifested as small, white-greyish spots with the occurrence of apical necrosis on garlic leaves. This necrosis was observed to enlarge, producing a water-soaked lesion before turning into a black-violet due to the formation of conidia. As the disease progressed, the infected leaves wilted, and the whole garlic plants eventually died. To identify the causal agent, symptomatic tissues (brown dried water-soak lesion) were excised, surface sterilized with 1% NaOCl and placed on the Potato Dextrose Agar (PDA) followed by incubation at 25°C in the dark for 5 days. Among ten fungal isolates obtained, four were selected for further analyses. On PDA, fungal colonies were initially greyish white in colour but gradually turned to yellowish-brown after 15 days due to the formation of yellow pigments. Conidia were muriform, brown in colour, oblong (almost round) with an average size of 18 – 22 × 16 – 20 μm (n = 50) and possessed 6 - 8 transverse septa. Fungal mycelia were branched, septate, and with smooth-walled hyphae. Morphological characteristics described above were consistent with the morphology of Stemphylium eturmiunum as reported by Simmons (Simmons, 2001). For molecular identification, molecular markers i.e. internal transcribed spacer (ITS) and calmodulin (cmdA) genes from the selected isolates were amplified and sequenced (White et al., 1990; Carbone and Kohn 1999). Alignment analysis shows that ITS and cmdA genes sequence is 100% identical among the four selected isolates. Therefore, representative isolate i.e. NIHHS 19-142 (KCTC56750) was selected for further analysis. BLASTN analysis showed that ITS (MW800165) and cmdA (LC601938) sequences of the representative isolates were 100% identical (523/523 bp and 410/410 bp) to the reference genes in Stemphylium eturmiunum isolated from Allium sativum in India (KU850545, KU850835) respectively (Woudenberg et al. 2017). Phylogenetic analysis of the concatenated sequence of ITS and cmdA genes confirmed NIHHS 19-142 isolates is Stemphylium eturmiunum. Pathogenicity test was performed using fungal isolate representative, NIHHS 19-142. Conidia suspension (1 × 106 conidia/µL) of the fungal isolate was inoculated on intact garlic leaves (two leaves from ten different individual plants were inoculated) and bulbs (ten bulbs were used) respectively. Inoculation on intact leaves was performed at NIHHS trial farm whereas inoculated bulbs were kept in the closed container to maintain humidity above 90% and incubated in the incubator chamber at 25°C. Result show that the formation of water-soaked symptoms at the inoculated site was observed at 14 dpi on intact leaves whereas 11 dpi on bulbs. As a control, conidia suspension was replaced with sterile water and the result shows no symptoms were observed on the control leaves and bulbs respectively. Re-identification of fungal colonies from symptomatic leaf and bulb was attempted. Result showed that the morphological characteristics and molecular marker sequences of the three colonies selected were identical to the original isolates thus fulfilled Koch’s postulates. Early identification of Stemphylium eturmiunum as a causal agent to leaf spot disease is crucial information to employ effective disease management strategies or agrochemical applications to control disease outbreaks in the field. Although Stemphylium eturmiunum has been reported to cause leaf spot of garlic disease in China, France and India (Woudenberg et al. 2017), to our knowledge, this is the first report of causing leaf spot disease on garlic in Korea.

scholarly journals First Report of Epicoccum nigrum Causing Brown Leaf Spot of Loquat in Southwestern China

Plant Disease ◽  
2017 ◽  
Vol 101 (8) ◽  
pp. 1553-1553 ◽  
Author(s):  
D. Wu ◽  
D. H. Zhang ◽  
M. P. Timko ◽  
M. Y. Li ◽  
G. L. Liang
Keyword(s):  
Leaf Spot ◽  
Southwestern China ◽  
First Report ◽  
Epicoccum Nigrum ◽  
Brown Leaf Spot ◽  
Brown Leaf

scholarly journals First Report of Bipolaris oryzae Causing Leaf Spot on Cultivated Wild Rice (Oryza rufipogon) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Ya Li ◽  
Hong Kai Zhou
Keyword(s):  
Leaf Spot ◽  
Wild Rice ◽  
Morphological Characteristics ◽  
Oryza Rufipogon ◽  
Likelihood Method ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Sterile Water ◽  
Bipolaris Oryzae ◽  
First Report

Wild rice (Oryza rufipogon) has been widely studied and cultivated in China in recent years due to its antioxidant activities and health-promoting effects. In December 2018, leaf spot disease on wild rice (O. rufipogon cv. Haihong-12) was observed in Zhanjiang (20.93 N, 109.79 E), China. The early symptom was small purple-brown lesions on the leaves. Then, the once-localized lesions coalesced into a larger lesion with a tan to brown necrotic center surrounded by a chlorotic halo. The diseased leaves eventually died. Disease incidence was higher than 30%. Twenty diseased leaves were collected from the fields. The margin of diseased tissues was cut into 2 × 2 mm2 pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s, and then rinsed three times with sterile water before isolation. The tissues were plated on potato dextrose agar (PDA) medium and incubated at 28 °C in the dark for 4 days. Pure cultures were produced by transferring hyphal tips to new PDA plates. Fifteen isolates were obtained. Two isolates (OrL-1 and OrL-2) were subjected to further morphological and molecular studies. The colonies of OrL-1 and OrL-1 on PDA were initially light gray, but it became dark gray with age. Conidiophores were single, straight to flexuous, multiseptate, and brown. Conidia were oblong, slightly curved, and light brown with four to nine septa, and measured 35.2–120.3 µm × 10.3–22.5 µm (n = 30). The morphological characteristics of OrL-1 and OrL-2 were consistent with the description on Bipolaris oryzae (Breda de Haan) Shoemaker (Manamgoda et al. 2014). The ITS region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and translation elongation factor (EF-1α) were amplified using primers ITS1/ITS4, GDF1gpp1/GDR1 gdp2 (Berbee et al. 1999), and EF-1α-F/EF-1α-R EF-1/EF-2 (O’Donnell 2000), respectively. Amplicons of OrL-1 and OrL-2 were sequenced and submitted to GenBank (accession nos. MN880261 and MN880262, MT027091 and MT027092, and MT027093 and MT027094). The sequences of the two isolates were 99.83%–100% identical to that of B. oryzae (accession nos. MF490854，MF490831，MF490810) in accordance with BLAST analysis. A phylogenetic tree was generated on the basis of concatenated data from the sequences of ITS, GAPDH, and EF-1α via Maximum Likelihood method, which clustered OrL-1 and OrL-2 with B. oryzae. The two isolates were determined as B. oryzae by combining morphological and molecular characteristics. Pathogenicity test was performed on OrL-1 in a greenhouse at 24 °C to 30 °C with 80% relative humidity. Rice (cv. Haihong-12) with 3 leaves was grown in 10 pots, with approximately 50 plants per pot. Five pots were inoculated by spraying a spore suspension (105 spores/mL) onto leaves until runoff occurred, and five pots were sprayed with sterile water and used as controls. The test was conducted three times. Disease symptoms were observed on leaves after 10 days, but the controls remained healthy. The morphological characteristics and ITS sequences of the fungal isolates re-isolated from the diseased leaves were identical to those of B. oryzae. B. oryzae has been confirmed to cause leaf spot on Oryza sativa (Barnwal et al. 2013), but as an endophyte has been reported in O. rufipogon (Wang et al. 2015).. Thus, this study is the first report of B. oryzae causing leaf spot in O. rufipogon in China. This disease has become a risk for cultivated wild rice with the expansion of cultivation areas. Thus, vigilance is required.

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