scholarly journals First Report of Leaf Spot Caused by Ramularia sphaeroidea on Vicia villosa var. glabrescens in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Min Shi ◽  
Yan Zhong Li
Keyword(s):  
Dna Sequences ◽  
Leaf Spot ◽  
Tween 80 ◽  
The United States ◽  
Diseased Plant ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Vicia Villosa ◽  
First Report

Hairy vetch Vicia villosa Roth is widely grown in southwestern China for green manure and forage. In December 2019, a leaf disease occurred on 80% plants of V. villosa var. glabrescens in an eight-hectare field in Qujing(N 25°28′12″, E 103°36′22″), Yunnan Province, China. The disease leaves had irregular, brown to dark brown leaf spots with white mold. Twenty diseased leaves from five plants were randomly collected from the field. The leaf samples were sterilized with 75% ethanol for 30 s and 1% NaClO for 75 s, rinsed three times with sterile distilled water, surface water removed with sterile filter paper, and placed onto potato dextrose agar (PDA) for culture at 20oC. The obtained fungal isolates were purified by transferring 1 to 2 mm hyphal tips onto fresh PDA plates and cultured under the same temperature condition. The isolates grew slowly, at a rate of 0.7 mm/d at 20℃ for 4 weeks. A diseased plant specimen (accession MHLZU19326) and three isolates (accessions YN1931401, YN1931402, and YN1931403) were deposited in the Mycological Herbarium of Lanzhou University (MHLZU). Conidia from the PDA cultures were hyaline, spherical, smooth, aseptate, and measured 2.13 to 3.67 × 4.56 to 5.77 μm (n = 50). Conidiophores were hyaline, smooth, and straight. DNA of purified isolates was extracted and the nuclear ribosomal internal transcribed spacer (ITS), tef1-α, his3 and gapdh genes were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990), EF1-728F/EF2 (Carbone and Kohn 1999;O’Donnell et al. 1998), CylH3F/CylH3R (Crous et al. 2004), and gpd1/gpd2 (Berbee et al. 1999), respectively. DNA sequences of isolates YN1931401, YN1931402, and YN1931403 were deposited in GenBank for the ITS (accessions MW092181, MW332205, and MW332206), tef1-α (MW448172 to MW448174), his3 (MW448175 to MW448177), and gapdh (MW448178 to MW448180). These sequences had the highest similarities with sequences of Ramularia sphaeroidea Sacc. in GenBank, 99%(514∕516, 515∕517, and 514∕517 bp) for ITS, 99% (402∕403, 403∕405, and 405∕405bp) for tef1-α, 99% (377∕378, 378∕378, and 376∕378bp) for his3, and 100% (558∕557, 557∕559 and 561∕565 bp) for gapdh . A phylogenetic tree generated with the sequences clustered the fungus closely with R. sphaeroidea. Infection experiments were carried out with 50 plants of V. villosa var. glabrescens in 10 pots. A conidial suspension of 1. 0 × 106 conidia/ml with 0.01% Tween 80 was prepared by adding sterile distilled water to the YN1931401 culture and scraping with a sterile scalpel. The leaves of 25 healthy plants were sprayed with the conidial suspension, and those of the 25 control plants were sprayed with sterile water. All plants were covered with clear polyethylene bags for 3 days to maintain high humidity and then grown in a greenhouse at diurnal cycles of 18℃ for 18h with light and 22℃ for 6 h in dark. Ten days post-inoculation, the inoculated plants exhibited brown lesions similar to the symptoms observed in the field (Fig. 1-F), whereas no symptoms appeared on the control plants. The same fungus was re-isolated and identified as described above. R. sphaeroidea has been reported on V. fabae and V. sativa in Ethiopia and Israel (Braun 1998), on various Vicia species including V. villosa in California, the United States (Koike et al. 2004) and on V. craccain China (Zhang et al. 2006), but to our knowledge, this is the first report of this fungus causing leaf spot on V. villosa in China.

scholarly journals First Report of Verticillium Wilt of Ailanthus altissima in Virginia Caused by Verticillium nonalfalfae

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 837-837 ◽  
Author(s):  
A. L. Snyder ◽  
M. T. Kasson ◽  
S. M. Salom ◽  
D. D. Davis ◽  
G. J. Griffin ◽  
...  
Keyword(s):  
Biological Control Agent ◽  
The United States ◽  
Ailanthus Altissima ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Tryptophan Synthase ◽  
Protein Coding ◽  
First Report ◽  
Protein Coding Genes

Ailanthus altissima (Mill.) Swingle, commonly known as tree-of-heaven, is an invasive tree species that has spread throughout the United States since its introduction in 1784 (2). During a survey in July 2009, approximately 1,100 A. altissima trees were observed at two locations in western Virginia (a roadside in Montgomery Co. and a wooded area adjacent to a railroad in Bedford Co.) exhibiting foliar wilt symptoms, defoliation, yellowish vascular discoloration, or death at an incidence of ~77%. Similar symptoms on A. altissima were reported in Roanoke, VA in the early 1930s and after 2005 in Pennsylvania, attributed to a Verticillium sp. (1,2). To identify the causal agent, discolored xylem tissue samples were excised from 10 symptomatic A. altissima trees at both locations, soaked in 1% NaOCl for 2 min, rinsed with sterilized distilled water for 5 min, and placed onto plum extract agar. Cultures were incubated in the dark at 22°C for 7 to 14 days. The resultant colonies (three to four per location) were subcultured and identified putatively as a Verticillium sp. closely related to Verticillium albo-atrum Reinke and Berthold (3), based on melanized, thick-walled, resting mycelia and phialides arranged in verticillate whorls that amassed round, oval-shaped conidia (5.1 ± 1.2 μm × 2.8 ± 0.4 μm, n = 100). Molecular identification of two fungal isolates (one per location) was determined by amplification of the protein coding genes elongation factor 1-alpha (EF), glyceraldehyde-3-phosphate dehydrogenase (GPD), and tryptophan synthase (TS), using PCR primers developed recently for Verticillium (3). A BLAST search on the edited contigs revealed 100% sequence similarity for all three protein coding genes among the two isolates and reference sequences of isolates PD592 (GenBank Accessions JN188227, JN188163, and JN188035 for EF, GPD, and TS, respectively) and VnAaPA140 (KC307764, KC307766, and KC307768 for EF, GPD, and TS, respectively) of the newly-proposed species, V. nonalfalfae (formerly V. albo-atrum). Aligned sequences from one representative isolate, VnAaVA2 (Bedford Co.), were deposited into GenBank as KC307758 (EF), KC307759 (GPD), and KC307760 (TS). To confirm pathogenicity to A. altissima, the two molecularly characterized isolates (one per location) were inoculated into 18 10-week old A. altissima stems that were grown in an environmental chamber at 24°C, 60% RH, and a 12-h photoperiod from seeds collected in Blacksburg, VA. A conidial suspension of each isolate was injected into each stem (0.1 ml of 1 × 108 CFU/ml/stem). All 36 seedlings inoculated with the proposed V. nonalfalfae isolates developed wilting of leaflets within 2 weeks post-inoculation (WPI), defoliation of leaflets by 6 WPI, and were dead by 9 WPI. Eighteen control seedlings were inoculated similarly with distilled water, and remained asymptomatic. Fungi resembling the proposed species V. nonalfalfae were reisolated from all inoculated stems except the control plants, and the species confirmed morphologically as described above. V. nonalfalfae is a recently proposed species that can infect a variety of plant species (3). To our knowledge, this is the first report of this proposed species on A. altissima in Virginia. New state reports of this pathogen on A. altissima are important for regulatory issues associated with using this pathogen as a potential biological control agent. References: (1) G. F. Gravatt and R. B. Clapper. Plant Dis. Rep. 16:96, 1932. (2) M. J. Schall and D. D. Davis. Plant Dis. 93:747, 2009. (3) P. Inderbitzin et al. PLoS ONE, 6, e28341, 2011.

scholarly journals The First Report of Leaf Spot Caused by Alternaria alternata on Italian Ryegrass (Lolium multiflorum) in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Xuekai Wei ◽  
Longhai Xue ◽  
Chunjie Li
Keyword(s):  
Alternaria Alternata ◽  
Leaf Spot ◽  
Lolium Multiflorum ◽  
Italian Ryegrass ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Forage Crops ◽  
Isolation Technique ◽  
First Report

Italian ryegrass (Lolium multiflorum Lam.) is one of the most important forage crops in southwestern China. In 2018, a leaf spot was observed in a field of Italian ryegrass in Mengyang, Sichuan province, China (30.96925°N, 104.10223°E). From January to early March, this leaf spot developed sporadically and appeared as brown to dark brown lesions. In late May, this disease reached a peak with incidence up to 80% and appeared as reddish-brown necrotic spots with a grayish white to brown center. To isolate the pathogen, sections (0.5 × 1 cm2) of 30 diseased leaves collected from 10 plants were surface-disinfested in 70% ethanol solution for 30 s, 5% NaOCl solution for 5 min, rinsed thrice in sterilized distilled water, air dried, plated on potato dextrose agar (PDA), and incubated at 25°C in the dark for 4 days. To obtain pure isolates, the single-spore isolation technique (Cai et al. 2009) was used. The conidial suspensions were diluted to a reasonable concentration, spread onto PDA, and incubated at 25°C in dark for 24 to 48 h, and then single germinated conidia were transferred onto new PDA plates (Cai et al. 2009). Nine pure isolates showing similar morphology were obtained for further study. Colonies on PDA were dark gray in the center surrounded by white to gray, with gossypine mycelia on the upper side, and red to dark red on the reverse side. Conidia were obclavate or pyriform, olivaceous to dark brown, with 0 to 6 transverse septa and 0 to 4 longitudinal septa, 13.2 to 55.0 (27.9) × 6.3 to 12.5 (9.8) µm. Conidiophores were septate, hyaline to olivaceous brown, either branched or unbranched, geniculate at the tip, 2.5 to 5.9 μm wide and up to 70 μm long. These morphological and cultural characteristics were consistent with the descriptions of Alternaria alternata (Fr.) Keissl. isolated from Apple (Elfar et al. 2018). To confirm the pathogenicity on Italian ryegrass, healthy plants (8-week-old) of cultivar Splendor grown in five pots filled with potting soil were spray-inoculated with conidial suspension (1 × 106 conidia/ml). Plants in another, five pots were sprayed with sterilized distilled water as controls. All pots were individually covered with transparent polyethylene bags for 5 days to maintain high relative humidity and placed in a greenhouse at 18 to 25°C. At 14 days post inoculation, symptoms typical of brown to dark brown leaf spots developed on the plants inoculated with conidial suspension, whereas no symptoms on the control plants. The pathogenicity tests were carried out three times. The same pathogen was consistently re-isolated from inoculated leaves and confirmed by morphological characterization as described above. To further identify this pathogen, isolate HMCH-9 (=CGMCC 3.19924) was selected as a representative for molecular characterization. Following Woudenberg et al. (2015), the internal transcribed spacer regions 1 and 2 and intervening 5.8S rDNA (ITS), glyceraldehyde-3-phosphate dehydrogenase (GPD), translation elongation factor 1-alpha (TEF), RNA polymerase second largest subunit (RPB2), and Alternaria major allergen (Alt) genes were partially amplified and sequenced. Sequences were deposited in GenBank (accession nos. MH567106 for ITS, MH567107 for GPD, MH567109 for TEF, MH567110 for RPB2, and MH567108 for Alt). BLAST analysis of all these five segments showed >99.8% identity with those sequences of ex-type isolate CBS 916.96 of A. alternata (Woudenberg et al. 2015). To our knowledge, this is the first report of A. alternata causing leaf spot on Italian ryegrass in China. The accurate identification of this pathogen would be useful for the prevention and control of leaf spot on Italian ryegrass in the future.

scholarly journals First Report of Pepper Fruit Rot Caused by Fusarium concentricum in China

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1657-1657 ◽  
Author(s):  
J. H. Wang ◽  
Z. H. Feng ◽  
Z. Han ◽  
S. Q. Song ◽  
S. H. Lin ◽  
...  
Keyword(s):  
Fusarium Species ◽  
Fruit Rot ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Average Growth ◽  
First Report ◽  
Control Fruit ◽  
Pepper Fruit ◽  
Fruit Samples

Pepper (Capsicum annuum L.) is an important vegetable crop worldwide. Some Fusarium species can cause pepper fruit rot, leading to significant yield losses of pepper production and, for some Fusarium species, potential risk of mycotoxin contamination. A total of 106 diseased pepper fruit samples were collected from various pepper cultivars from seven provinces (Gansu, Hainan, Heilongjiang, Hunan, Shandong, Shanghai, and Zhejiang) in China during the 2012 growing season, where pepper production occurs on approximately 25,000 ha. Pepper fruit rot symptom incidence ranged from 5 to 20% in individual fields. Symptomatic fruit tissue was surface-sterilized in 0.1% HgCl2 for 1 min, dipped in 70% ethanol for 30 s, then rinsed in sterilized distilled water three times, dried, and plated in 90 mm diameter petri dishes containing potato dextrose agar (PDA). After incubation for 5 days at 28°C in the dark, putative Fusarium colonies were purified by single-sporing. Forty-three Fusarium strains were isolated and identified to species as described previously (1,2). Morphological characteristics of one strain were identical to those of F. concentricum. Aerial mycelium was reddish-white with an average growth rate of 4.2 to 4.3 mm/day at 25°C in the dark on PDA. Pigments in the agar were formed in alternating red and orange concentric rings. Microconidia were 0- to 1-septate, mostly 0-septate, and oval, obovoid to allantoid. Macroconidia were relatively slender with no significant curvature, 3- to 5-septate, with a beaked apical cell and a foot-shaped basal cell. To confirm the species identity, the partial TEF gene sequence (646 bp) was amplified and sequenced (GenBank Accession No. KC816735). A BLASTn search with TEF gene sequences in NCBI and the Fusarium ID databases revealed 99.7 and 100% sequence identity, respectively, to known TEF sequences of F. concentricum. Thus, both morphological and molecular criteria supported identification of the strain as F. concentricum. This strain was deposited as Accession MUCL 54697 (http://bccm.belspo.be/about/mucl.php). Pathogenicity of the strain was confirmed by inoculating 10 wounded, mature pepper fruits that had been harvested 70 days after planting the cultivar Zhongjiao-5 with a conidial suspension (1 × 106 spores/ml), as described previously (3). A control treatment consisted of inoculating 10 pepper fruits of the same cultivar with sterilized distilled water. The fruit were incubated at 25°C in a moist chamber, and the experiment was repeated independently in triplicate. Initially, green to dark brown lesions were observed on the outer surface of inoculated fruit. Typical soft-rot symptoms and lesions were observed on the inner wall when the fruit were cut open 10 days post-inoculation. Some infected seeds in the fruits were grayish-black and covered by mycelium, similar to the original fruit symptoms observed at the sampling sites. The control fruit remained healthy after 10 days of incubation. The same fungus was isolated from the inoculated infected fruit using the method described above, but no fungal growth was observed from the control fruit. To our knowledge, this is the first report of F. concentricum causing a pepper fruit rot. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (2) K. O'Donnell et al. Proc. Nat. Acad. Sci. USA 95:2044, 1998. (3) Y. Yang et al. 2011. Int. J. Food Microbiol. 151:150, 2011.

scholarly journals First Report of Leaf Spot of Rudbeckia hirta var. pulcherrima Caused by Septoria rudbeckiae in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 911-911 ◽  
Author(s):  
J. H. Park ◽  
S. E. Cho ◽  
K. S. Han ◽  
H. D. Shin
Keyword(s):  
Leaf Spot ◽  
The United States ◽  
Flowering Plant ◽  
Leaf Spot Disease ◽  
Morphological Identification ◽  
Its Sequence ◽  
Conidial Suspension ◽  
First Report ◽  
Rudbeckia Hirta ◽  
Close Phylogenetic Relationship

Rudbeckia hirta L. var. pulcherrima Farw. (synonym R. bicolor Nutt.), known as the black-eyed Susan, is a flowering plant belonging to the family Asteraceae. The plant is native to North America and was introduced to Korea for ornamental purposes in the 1950s. In July 2011, a previously unknown leaf spot was first observed on the plants in a public garden in Namyangju, Korea. Leaf spot symptoms developed from lower leaves as small, blackish brown lesions, which enlarged to 6 mm in diameter. In the later stages of disease development, each lesion was usually surrounded with a yellow halo, detracting from the beauty of the green leaves of the plant. A number of black pycnidia were present in diseased leaf tissue. Later, the disease was observed in several locations in Korea, including Pyeongchang, Hoengseong, and Yangpyeong. Voucher specimens were deposited at the Korea University Herbarium (KUS-F25894 and KUS-F26180). An isolate was obtained from KUS-F26180 and deposited at the Korean Agricultural Culture Collection (Accession No. KACC46694). Pycnidia were amphigenous, but mostly hypogenous, scattered, dark brown-to-rusty brown, globose, embedded in host tissue or partly erumpent, 50 to 80 μm in diameter, with ostioles 15 to 25 μm in diameter. Conidia were substraight to mildly curved, guttulate, hyaline, 25 to 50 × 1.5 to 2.5 μm, and one- to three-septate. Based on the morphological characteristics, the fungus was consistent with Septoria rudbeckiae Ellis & Halst. (1,3,4). Morphological identification of the fungus was confirmed by molecular data. Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA.). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 528 bp was deposited in GenBank (Accession No. JQ677043). A BLAST search showed that there was no matching sequence of S. rudbeckiae; therefore, this is the first ITS sequence of the species submitted to GenBank. The ITS sequence showed >99% similarity with those of many Septoria species, indicating their close phylogenetic relationship. Pathogenicity was tested by spraying leaves of three potted young plants with a conidial suspension (2 × 105 conidia/ml), which was harvested from a 4-week-old culture on potato dextrose agar. Control leaves were sprayed with sterile water. The plants were covered with plastic bags to maintain 100% relative humidity (RH) for the first 24 h. Plants were then maintained in a greenhouse (22 to 28°C and 70 to 80% RH). After 5 days, leaf spot symptoms identical to those observed in the field started to develop on the leaves inoculated with the fungus. No symptoms were observed on control plants. S. rudbeckiae was reisolated from the lesions of inoculated plants, confirming Koch's postulates. A leaf spot disease associated with S. rudbeckiae has been reported on several species of Rudbeckia in the United States, Romania, and Bulgaria (1–4). To our knowledge, this is the first report of leaf spot on R. hirta var. pulcherrima caused by S. rudbeckiae in Korea. References: (1) J. B. Ellis and B. D. Halsted. J. Mycol. 6:33, 1890. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ February 2, 2012. (3) E. Radulescu et al. Septoriozele din Romania. Ed. Acad. Rep. Soc. Romania, Bucuresti, Romania, 1973. (4) S. G. Vanev et al. Fungi Bulgaricae 3:1, 1997.

scholarly journals First Report of Diaporthe hongkongensis Causing Fruit rot on Peach (Prunus persica) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zhou Zhang ◽  
Zheng Bing Zhang ◽  
Yuan Tai Huang ◽  
FeiXiang Wang ◽  
Wei Hua Hu ◽  
...  
Keyword(s):  
Prunus Persica ◽  
Fruit Rot ◽  
Hunan Province ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Representative Isolate ◽  
Rot Disease

Peach [Prunus persica (L.) Batsch] is an important deciduous fruit tree in the family Rosaceae and is a widely grown fruit in China (Verde et al., 2013). In July and August 2018, a fruit rot disease was observed in a few peach orchards in Zhuzhou city, the Hunan Province of China. Approximately 30% of the fruit in more than 400 trees was affected. Symptoms displayed were brown necrotic spots that expanded, coalesced, and lead to fruit being rotten. Symptomatic tissues excised from the margins of lesions were surface sterilized in 70% ethanol for 10 s, 0.1% HgCl2 for 2 min, rinsed with sterile distilled water three times, and incubated on potato dextrose agar (PDA) at 26°C in the dark. Fungal colonies with similar morphology developed, and eight fungal colonies were isolated for further identification. Colonies grown on PDA were grayish-white with white aerial mycelium. After an incubation period of approximately 3 weeks, pycnidia developed and produced α-conidia and β-conidia. The α-conidia were one-celled, hyaline, fusiform, and ranged in size from 6.0 to 8.4 × 2.1 to 3.1 μm, whereas the β-conidia were filiform, hamate, and 15.0 to 27.0 × 0.8 to 1.6 μm. For molecular identification, total genomic DNA was extracted from the mycelium of a representative isolate HT-1 and the internal transcribed spacer region (ITS), β-tubulin gene (TUB), translation elongation factor 1-α gene (TEF1), calmodulin (CAL), and histone H3 gene (HIS) were amplified and sequenced (Meng et al. 2018). The ITS, TUB, TEF1, CAL and HIS sequences (GenBank accession nos. MT740484, MT749776, MT749778, MT749777, and MT749779, respectively) were obtained and in analysis by BLAST against sequences in NCBI GenBank, showed 99.37 to 100% identity with D. hongkongensis or D. lithocarpus (the synonym of D. hongkongensis) (Gao et al., 2016) (GenBank accession nos. MG832540.1 for ITS, LT601561.1 for TUB, KJ490551.1 for HIS, KY433566.1 for TEF1, and MK442962.1 for CAL). Pathogenicity tests were performed on peach fruits by inoculation of mycelial plugs and conidial suspensions. In one set, 0.5 mm diameter mycelial discs, which were obtained from an actively growing representative isolate of the fungus on PDA, were placed individually on the surface of each fruit. Sterile agar plugs were used as controls. In another set, each of the fruits was inoculated by application of 1 ml conidial suspension (105 conidia/ml) by a spray bottle. Control assays were carried out with sterile distilled water. All treatments were maintained in humid chambers at 26°C with a 12-h photoperiod. The inoculation tests were conducted twice, with each one having three fruits as replications. Six days post-inoculation, symptoms of fruit rot were observed on inoculated fruits, whereas no symptoms developed on fruits treated with agar plugs and sterile water. The fungus was re-isolated and identified to be D. hongkongensis by morphological and molecular methods, thus fulfilling Koch’s Postulates. This fungus has been reported to cause fruit rot on kiwifruit (Li et al. 2016) and is also known to cause peach tree dieback in China (Dissanayake et al. 2017). However, to our knowledge, this is the first report of D. hongkongensis causing peach fruit rot disease in China. The identification of the pathogen will provide important information for growers to manage this disease.

scholarly journals First Report of Phomopsis citri Associated with Dieback of Citrus lemon in India

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1281-1281 ◽  
Author(s):  
S. Mahadevakumar ◽  
Vandana Yadav ◽  
G. S. Tejaswini ◽  
S. N. Sandeep ◽  
G. R. Janardhana
Keyword(s):  
Fungal Pathogen ◽  
The United States ◽  
Apical Region ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
Productivity Level ◽  
First Report ◽  
Dieback Disease

Lemon (Citrus lemon (L.) Burm. f.) is an important fruit crop cultivated worldwide, and is grown practically in every state in India (3). During a survey conducted in 2013, a few small trees in a lemon orchard near Mysore city (Karnataka) (12°19.629′ N, 76°31.892′ E) were found affected by dieback disease. Approximately 10 to 20% of trees were affected as young shoots and branches showed progressive death from the apical region downward. Different samples were collected and diagnosed via morphological methods. The fungus was consistently isolated from the infected branches when they were surface sanitized with 1.5% NaOCl and plated on potato dextrose agar (PDA). Plates were incubated at 26 ± 2°C for 7 days at 12/12 h alternating light and dark period. Fungal colonies were whitish with pale brown stripes having an uneven margin and pycnidia were fully embedded in the culture plate. No sexual state was observed. Pycnidia were globose, dark, 158 to 320 μm in diameter, and scattered throughout the mycelial growth. Both alpha and beta conidia were present within pycnidia. Alpha conidia were single celled (5.3 to 8.7 × 2.28 to 3.96 μm) (n = 50), bigittulate, hyaline, with one end blunt and other truncated. Beta conidia (24.8 to 29.49 × 0.9 to 1.4 μm) (n = 50) were single celled, filiform, with one end rounded and the other acute and curved. Based on the morphological and cultural features, the fungal pathogen was identified as Phomopsis citri H.S. Fawc. Pathogenicity test was conducted on nine healthy 2-year-old lemon plants via foliar application of a conidial suspension (3 × 106); plants were covered with polythene bags for 6 days and maintained in the greenhouse. Sterile distilled water inoculated plants (in triplicate) served as controls and were symptomless. Development of dieback symptoms was observed after 25 days post inoculation and the fungal pathogen was re-isolated from the inoculated lemon trees. The internal transcribed spacer region (ITS) of the isolated fungal genomic DNA was amplified using universal-primer pair ITS1/ITS4 and sequenced to confirm the species-level diagnosis (4). The sequence data of the 558-bp amplicon was deposited in GenBank (Accession No. KJ477016.1) and nBLAST search showed 99% homology with Diaporthe citri (teleomorph) strain 199.39 (KC343051.1). P. citri is known for its association with melanose disease of citrus in India, the United States, and abroad. P. citri also causes stem end rot of citrus, which leads to yield loss and reduction in fruit quality (1,2). Dieback disease is of serious concern for lemon growers as it affects the overall productivity level of the tree. To the best of our knowledge, this is the first report of P. citri causing dieback of lemon in India. References: (1) I. H. Fischer et al. Sci. Agric. (Piracicaba). 66:210, 2009. (2) S. N. Mondal et al. Plant Dis. 91:387, 2007. (3) S. P. Raychaudhuri. Proc. Int. Soc. Citriculture 1:461, 1981. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Leaf Spot Disease Caused by Epicoccum nigrum on Lablab purpureus in India

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 284-284 ◽  
Author(s):  
S. Mahadevakumar ◽  
K. M. Jayaramaiah ◽  
G. R. Janardhana
Keyword(s):  
Leaf Spot ◽  
Leaf Surface ◽  
Disease Incidence ◽  
Leaf Spot Disease ◽  
Post Inoculation ◽  
Conidial Suspension ◽  
Lablab Purpureus ◽  
First Report ◽  
Spot Disease ◽  
Epicoccum Nigrum

Lablab purpureus (L.) Sweet (Indian bean) is an important pulse crop grown in arid and semi-arid regions of India. It is one of the most widely cultivated legume species and has multiple uses. During a September 2010 survey, we recorded a new leaf spot disease on L. purpureus in and around Mysore district (Karnataka state) with 40 to 80% disease incidence in 130 ha of field crop studied, which accounted for 20 to 35% estimated yield loss. The symptoms appeared as small necrotic spots on the upper leaf surface. The leaf spots were persistent under mild infection throughout the season with production of conidia in clusters on abaxial leaf surface. A Dueteromyceteous fungus was isolated from affected leaf tissues that were surface sterilized with 2% NaOCl2 solution then washed thrice, dried, inoculated on potato dextrose agar (PDA) medium, and incubated at 28 ± 2°C at 12 h alternate light and dark period for 7 days. The fungal colony with aerial mycelia interspersed with dark cushion-shaped sporodochia consists of short, compact conidiophores bearing large isodiametric, solitary, muricate, brown, globular to pear shaped conidia (29.43 to 23.92 μm). Fungal isolate was identified as Epicoccum sp. based on micro-morphological and cultural features (1). Further authenticity of the fungus was confirmed by PCR amplification of the internal transcribed spacer (ITS) region using ITS1/ITS4 universal primer. The amplified PCR product was purified, sequenced directly, and BLASTn search revealed 100% homology to Epicoccum nigrum Link. (DQ093668.1 and JX914480.1). A representative sequence of E. nigrum was deposited in GenBank (Accession No. KC568289.1). The isolated fungus was further tested for its pathogenicity on 30-day-old healthy L. purpureus plants under greenhouse conditions. A conidial suspension (106 conidia/ml) was applied as foliar spray (three replicates of 15 plants each) along with suitable controls. The plants were kept under high humidity (80%) for 5 days and at ambient temperature (28 ± 2°C). The appearance of leaf spot symptoms were observed after 25 days post inoculation. Further, the pathogen was re-isolated and confirmed by micro-morphological characteristics. E. nigrum has been reported to cause post-harvest decay of cantaloupe in Oklahoma (2). It has also been reported as an endophyte (3). Occurrence as a pathogen on lablab bean has not been previously reported. To our knowledge, this is the first report of the occurrence of E. nigrum on L. purpureus in India causing leaf spot disease. References: (1) H. L. Barnet and B. B. Hunter. Page 150 in: Illustrated Genera of Imperfect Fungi, 1972. (2) B. D. Bruten et al. Plant Dis. 77:1060, 1993. (3) L. C. Fávaro et al. PLoS One 7(6):e36826, 2012.

scholarly journals First report of Fusarium incarnatum causing spikelet rot on rice in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Ling Wang ◽  
S. L. Ge ◽  
Kehan Zhao ◽  
huang Shiwen
Keyword(s):  
Natural Science ◽  
Disease Incidence ◽  
Science And Technology ◽  
Agricultural Science ◽  
Zhejiang Province ◽  
Maturity Stage ◽  
Post Inoculation ◽  
Distilled Water ◽  
Conidial Suspension ◽  
First Report

Rice (Oryza sativa L.) is the most important and widely grown crop, covering about 29.9 million ha of total cultivation area in China. In the last decade, spikelet rot disease on rice became much more frequent in the middle and lower reaches of the Yangtze River, China. Fusarium proliferatum (Matsush.) Nirenberg ex Gerlach & Nirenberg was reported to be a causal agent of spikelet rot on rice in Hangzhou, Zhejiang province (Huang et al. 2012). In September 2019, a survey was conducted to understand the etiology of the disease in the main rice growing regions of Jinshan District of Shanghai. Symptomatic panicles exhibiting reddish or brown discoloration on the glumes were collected from different rice fields, where disease incidence was estimated to be between 20 to 80%. Diseased glumes were cut into small sections (5 × 5 mm) from the boundary of necrotic and healthy tissues, surface-sterilized with 75% ethanol for 30 s and 3% sodium hypochlorite for 90 s, rinsed twice with sterile distilled water, then placed onto 1/5 strength potato dextrose agar (PDA). After 3 to 5 days of incubation at 28°C in the dark, fungal growth with Fusarium-like colonies were transferred to PDA and purified by the single-spore isolation method. A total of 12 isolates were obtained and colonies showed loosely floccose, white mycelium and pale-yellow pigmentation on PDA. Microconidia were ovoid mostly with 0 to 1 septum, and measured 4.2 to 16.6 × 2.5 to 4.1 μm (n = 50). After 5-7 days of inoculation on carnation leaf agar (CLA), macroconidia produced usually had 3 to 5 septa, slightly curved at the apex, ranging from 15.7 to 39.1 × 3.3 to 5.0 μm (n = 50). Chlamydospores were produced in hyphae, most often solitary in short chains or in clumps, ellipsoidal or subglobose with thick and roughened walls. Molecular identification was performed on the representative isolates (JS3, JS9, and JS21). The rDNA internal transcribed spacer (ITS), translation elongation factor (TEF-1α) and β-tubulin (β-TUB) genes were amplified and sequenced using the paired primers ITS1/ITS4 (White et al. 1990), EF1/EF2 (O’Donnell et al. 1998) and T1/T22 (O’Donnell and Cigelnik 1997), respectively. The obtained sequences were deposited in GenBank under accession numbers MT889972 to MT889974 (ITS), MT895844 to MT895846 (TEF-1α), and MT895841 to MT895843 (β-TUB), respectively. BLASTn search of the sequences revealed 99 to 100% identity with ITS (MF356578), TEF-1α (HM770725) and β-TUB (GQ915444) of Fusarium incarnatum isolates. FUSARIUM-ID (Geiser et al. 2004) analysis showed 99 to 100% similarity with sequences of the F. incarnatum-equiseti species complex (FIESC) (FD_01651 and FD_01628). In addition, a phylogenetic analysis based on the concatenated nucleotide sequences placed the isolates in the F. incarnatum clade at 100% bootstrap support. Thus, both morphological observations and molecular criteria supported identification of the isolates as F. incarnatum (Desm.) Sacc (synonym: Fusarium semitectum) (Leslie and Summerell 2006, Nirenberg 1990). Pathogenicity tests were performed on susceptible rice cultivar ‘Xiushui134’. At pollen cell maturity stage, a 2-ml conidial suspension (5 × 105 macroconidia/ml) of each isolate was injected into 10 rice panicles. Control plants were inoculated with sterile distilled water. Then, the pots were kept in a growth chamber at 28°C, 80% relative humidity, and 12 h/12 h light (10,000 lux)/dark. The experiment was repeated two times for each isolate. Two weeks post-inoculation, all inoculated panicles showed similar symptoms with the original samples, whereas no symptoms were observed on the control. The pathogen was re-isolated from inoculated panicles and identified by the method described above to fulfill Koch's postulates. Previous studies reported that F. incarnatum reproduced perithecia to overwinter on rice stubble as the inoculum of Fusarium head blight of wheat in southern China (Yang et al. 2018). To our knowledge, this is the first report of spikelet rot on rice caused by F. incarnatum in China. Further investigation is needed to gain a better understanding its potential geographic distribution of this new pathogen on rice crop. References: (1) Huang, S. W., et al. 2011. Crop Prot. 30: 10. (2) White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. (3) O’Donnell, K., et al. 1998. Proc. Natl. Acad. Sci. U.S.A. 95: 2044. (4) O'Donnell, K., Cigelnik, E. 1997. Mol. Phylogenet. Evol. 7: 103. (5) Geiser, D. M., et al. 2004. Eur. J. Plant Pathol. 110: 473. (6) Leslie, J. F., and Summerell, B. A. 2006. The Fusarium Laboratory Manual. Blackwell, Ames, IA. (7) Nirenberg, H. I. 1990. Stud. Mycol. 32: 91. (8) Yang, M. X., et al. 2018. Toxins. 10: 115. The author(s) declare no conflict of interest. Funding: Funding was provided by National Natural Science Foundation of China (grant no. 31800133), Zhejiang Provincial Natural Science Foundation of China (grant no. LQ18C140005), Key Research and Development Program of Zhejiang Province (grant no. 2019C02018), Shanghai Science and Technology for Agriculture Promotion Project (2019-02-08-00-08-F01127), and the Agricultural Science and Technology Innovation Program of China Academy of Agricultural Science (CAAS-ASTIP-2013- CNRRI).

scholarly journals First Report of Myrothecium roridum Causing Myrothecium Leaf Spot on Salvia spp. in the United States

Plant Disease ◽  
2007 ◽  
Vol 91 (6) ◽  
pp. 772-772 ◽  
Author(s):  
J. A. Mangandi ◽  
T. E. Seijo ◽  
N. A. Peres
Keyword(s):  
United States ◽  
Leaf Spot ◽  
Pathogenic Fungi ◽  
Lower Surface ◽  
The United States ◽  
Plant Diseases ◽  
Control Measures ◽  
Conidial Suspension ◽  
First Report ◽  
Myrothecium Roridum

The genus Salvia includes at least 900 species distributed worldwide. Wild species are found in South America, southern Europe, northern Africa, and North America. Salvia, commonly referred to as sage, is grown commercially as a landscape plant. In August 2006, pale-to-dark brown, circular leaf spots 5 to 20 mm in diameter with concentric rings were observed on Salvia farinacea ‘Victoria Blue’. Approximately 5% of the plants in a central Florida nursery were affected. Lesions were visible on both leaf surfaces, and black sporodochia with white, marginal hyphal tuffs were present mostly on the lower surface in older lesions. Symptoms were consistent with those of Myrothecium leaf spot described on other ornamentals such as gardenia, begonia, and New Guinea impatiens (4). Isolations from lesions on potato dextrose agar produced white, floccose colonies with sporodochia in dark green-to-black concentric rings. Conidia were hyaline and cylindrical with rounded ends and averaged 7.4 × 2.0 μm. All characteristics were consistent with the description of Myrothecium roridum Tode ex Fr. (2,3). The internal transcribed spacer regions ITS1, ITS2, and the 5.8s rRNA genomic region of one isolate were sequenced (Accession No. EF151002) and compared with sequences in the National Center for Biotechnology Information (NCBI) database. Deposited sequences from M. roridum were 96.3 to 98.8% homologous to the isolate from salvia. To confirm pathogenicity, three salvia plants were inoculated by spraying with a conidial suspension of M. roridum (1 × 105 conidia per ml). Plants were covered with plastic bags and incubated in a growth chamber at 28°C for 7 days. Three plants were sprayed with sterile, distilled water as a control and incubated similarly. The symptoms described above were observed in all inoculated plants after 7 days, while control plants remained symptomless. M. roridum was reisolated consistently from symptomatic tissue. There are more than 150 hosts of M. roridum, including one report on Salvia spp. in Brunei (1). To our knowledge, this is the first report of Myrothecium leaf spot caused by M. roridum on Salvia spp. in the United States. Even the moderate level disease present caused damage to the foliage and reduced the marketability of salvia plants. Therefore, control measures may need to be implemented for production of this species in ornamental nurseries. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2006, (2) M. B. Ellis. Page 449 in: Microfungi on Land Plants: An Identification Handbook. Macmillan Publishing, NY, 1985. (3) M. Fitton and P. Holliday. No. 253 in: CMI Descriptions of Pathogenic Fungi and Bacteria. The Eastern Press Ltd. Great Britain, 1970. (4) M. G. Daughtrey et al. Page 19 in: Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society. St. Paul, MN, 1995.

scholarly journals First Report of Curvularia gladioli Causing a Leaf Spot on Gladiolus grandiflorus in Brazil

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 847-847 ◽  
Author(s):  
D. P. Torres ◽  
M. A. Silva ◽  
D. B. Pinho ◽  
O. L. Pereira ◽  
G. Q. Furtado
Keyword(s):  
Leaf Spot ◽  
Central Cell ◽  
Post Inoculation ◽  
Intermediate Cell ◽  
Conidial Suspension ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
The Third ◽  
Leaf Spots

Gladiolus (Iridaceae) is a popular bulbous plant grown worldwide as an ornamental garden plant or cut flower due to its attractive color, size, and flower shape. In April 2012, leaf spots were observed on plants of Gladiolus grandiflorus varieties T-704 and Amsterdam growing in a production area of cut flowers located in the city of Viçosa, Minas Gerais. The oval to round leaf spots were brown with a dark border surrounded by a halo of yellow tissue. Infected leaf samples were deposited in the herbarium at the Universidade Federal de Viçosa (VIC31897). A fungus was isolated from the leaf spots and a single-spore pure culture was initiated and grown on corn meal carrot agar (CCA) medium in petri dishes incubated at 25°C under a 12-h photoperiod for 4 weeks. A sporulating single-spore culture was deposited at the Coleção de Culturas de fungos fitopatogênicos “Prof. Maria Menezes” (UFRPE, Brazil) code CMM 4055. On CCA medium, the fungal isolate initially appeared white, becoming dark after 14 days. Thirty conidia and conidiophores were measured for identification to species. The septate, smooth to pale brown conidiophores were present singly or in groups. The simple, straight or flexuous conidiophores were 42.5 to 82.5 × 3.5 to 7.5 μm and some had a geniculate growth pattern. The majority of conidia were curved at the third (central) cell from the base, which was usually enlarged compared to the end cells. The cells at each end of the 3-distoseptate conidia were pale brown, the intermediate cell brown or dark brown, and the third (central) cell was often the darkest. The basal cell had a protuberant hilum. Conidia were smooth and 20.0 to 33.5 × 10 to 17.5 μm. These characteristics matched well with the description of Curvularia gladioli (1). To confirm this identification, DNA was extracted using a Wizard Genomic DNA Purification Kit and the internal transcribed spacer region (ITS) of rDNA was amplified using ITS1 and ITS4 primers and the partial 28S rDNA region using primers LR0R and LR5. The sequences were deposited in GenBank as accession nos. JX995106 and JX995107, respectively. The ITS sequence matched sequence AF071337, C. gladioli, with 100% identity. This pathogen was first identified as C. lunata, but based on the characteristic of the hilum, spore size, and pathogenicity testing, the fungus was renamed C. trifolii f. sp. gladioli (3). Due to the explicit curvature of the conidia at the third cell and molecular data, the fungus was reclassified as C. gladioli (1,2). To confirm Koch's postulates, 1-month-old healthy plants of G. grandiflorus var. T-704 and Amsterdam (five plants each) were inoculated with a conidial suspension (2 × 104 conidia mL–1) by spraying the foliage and then placed on a growth chamber at 25°C. The control plants were sprayed with distilled water. Symptoms were consistent with those initially observed and all plants developed leaf spots by 4 days post-inoculation. C. gladioli was consistently recovered from the symptomatic tissue and control plants remained symptomless. To our knowledge, this is the first report of C. gladioli causing leaf spot on G. grandiflorus in Brazil. Due to a lack of chemical fungicides for management of this pathogen, further studies to evaluate the susceptibility of the main varieties of gladiolus grown in Brazil to C. gladioli may be necessary. References: (1) G. H. Boerema and M. E. C. Hamers. Neth. J. Plant Pathol. 95:1, 1989. (2) D. S. Manamgoda et al. Fungal Divers. 56:131, 2012. (3) J. A. Parmelee. Mycologia 48:558, 1956.

Sign in / Sign up

Export Citation Format

Share Document