First Report of Ascochyta rabiei Causing Ascochyta Blight of Chickpea in Argentina

In November 2011, lesions similar to those reported for Ascochyta blight (1) were observed on Cicer arietinum L. (chickpea) plants growing in three commercial fields located at Río Primero and Río Segundo (Cordoba Province) and Lobería (Buenos Aires Province), Argentina. Disease incidence (percentage of plants affected) was 100% in all fields surveyed. Plants showed leaves, petioles, stems, and pods with brown lesions. Symptoms on leaves and pods were circular to oval (2 to 14 mm) while in the stems the lesions were elongated (2 to 30 mm). Seeds appeared small and shriveled with brown discoloration. Morphology of the fungi was examined on infected tissues. Numerous black pycnidia measuring 94.6 to 217.9 μm (145.9 ± 28.8 μm), arranged in concentric rings, were observed within of all the lesions. Conidia were predominantly aseptate, straight, hyaline with blunt ends, and measured 9.3 to 12.9 (11.3 ± 1.12) × 3.3 to 5.0 μm (4.2 ± 0.51). Morphological characteristics of the pathogen were similar to those described for Ascochyta rabiei (Pass.) Labrousse (teleomorph Didymella rabiei (Kovacheski) v. Arx (= Mycosphaerella rabiei Kovacheski)) (2). Fungus from infected leaf tissues was isolated on potato dextrose agar. Pathogenicity tests were conducted on seedlings of the susceptible cultivar by spraying leaves of each of 100 seedling plants with 10 ml of a conidial suspension (2 × 104 conidia/ml) of the isolated pathogen with a handheld atomizer. Plants were covered with plastic bags and placed in a growing chamber at 20 to 25°C for 3 days. The plastic bags were removed and the plants were maintained in high humidity at the same temperature. Noninoculated plants were used as controls. After 5 days, all inoculated plants showed typical symptoms. Foliar and stem lesions symptoms were similar to those originally observed in the field. Control plants remained healthy. Koch's postulates were fulfilled by isolating A. rabiei from inoculated plants. The colonies and the morphology of conidia were the same as those of the original isolates. To our knowledge, this is the first report of A. rabiei infecting chickpeas in Argentina. The outbreak of Ascochyta blight in Argentina is of concern because of its severity and the possibility that the pathogen was introduced on seed. This report underscores the need for further research on effective management programs for Ascochyta blight. References: (1) B. Bayaa and W. Chen. Compendium of Chickpea and Lentil Diseases and Pests The American Phytopathological Society, St. Paul, MN, 2011. (2) E. Punithalingam and P. Holliday. Page 337 in: CMI Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1972.

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First Report of Ascochyta Leaf Spot Caused by Phoma exigua var. exigua on Common Bean in Greece

Plant Disease ◽

10.1094/pdis-92-4-0653c ◽

2008 ◽

Vol 92 (4) ◽

pp. 653-653 ◽

Cited By ~ 3

Author(s):

G. A. Bardas ◽

G. T. Tziros ◽

K. Tzavella-Klonari

Keyword(s):

Common Bean ◽

Leaf Spot ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Weather Conditions ◽

Conidial Suspension ◽

Phoma Exigua ◽

First Report ◽

Plastic Bags ◽

And Control

Common bean (Phaseolus vulgaris L.) is cultivated extensively in Greece for dry and fresh bean production. During 2005 and 2006, a disease with typical blight symptoms was observed occasionally on dark red kidney, brown kidney, and black bean plants in most bean-producing areas of Greece. It rarely was destructive unless the crop had been weakened by some unfavorable environmental conditions. Infected leaves had brown-to-black lesions that developed concentric zones 10 to 30 mm in diameter and also contained small, black pycnidia. Concentric dark gray-to-black lesions also appeared on branches, stems, nodes, and pods. Infected seeds turned brown to black. Plants sometimes showed defoliation and pod drop. The fungus was consistently isolated on potato dextrose agar from diseased leaves and pods and identified as Phoma exigua var. exigua Sutton and Waterstone on the basis of morphological characteristics of conidia and pycnidia (1,2). Spores were massed in pycnidia from which they were forced in long, pink tendrils under moist weather conditions. Conidia were cylindrical to oval, allantoid, hyaline, pale yellow to brown, usually one-celled, and 2 to 3 × 5 to 10 μm. To satisfy Koch's postulates, a conidial suspension (1 × 106 conidia per ml) of the fungus was sprayed onto leaves and stems of bean seedlings (first-leaf stage) (cv. Zargana Hrisoupolis). Both inoculated and control seedlings (inoculated with sterile water) were covered with plastic bags for 72 h in a greenhouse at 23°C. Inoculated plants showed characteristic symptoms of Ascochyta leaf spot 12 to 15 days after inoculation. The fungus was reisolated from lesions that developed on the leaves and stems of all inoculated plants. The pathogen is present worldwide on bean. To our knowledge, this is the first report of P. exigua var. exigua on common bean in Greece. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2007. (2) B. C. Sutton and J. M. Waterstone. Ascochyta phaseolorum. No. 81 in: Descriptions of Pathogenic Fungi and Bacteria. CMI/AAB, Kew, Surrey, England, 1966.

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First Report of Anthracnose Caused by Glomerella cingulata on Passion Fruit in Argentina

Plant Disease ◽

10.1094/pdis.2000.84.6.706a ◽

2000 ◽

Vol 84 (6) ◽

pp. 706-706 ◽

Cited By ~ 4

Author(s):

S. Wolcan ◽

S. Larran

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Passion Fruit ◽

High Yield ◽

Conidial Suspension ◽

Glomerella Cingulata ◽

First Report ◽

Plastic Bags ◽

Subtropical Fruit

Passion fruit (Passiflora edulis Sims.) is a subtropical fruit recently cultivated in Misiones Province, Argentina. In spring 1997, a severe epidemic of anthracnose was observed. Disease incidence was ≍95%, causing high yield losses. Sunken, gray lesions on the whole surface of young fruits were observed. Under humid conditions, acervuli containing masses of spores and dark setae were found within lesions. On leaves, tendrils, and twigs, circular and irregular brown spots with darker edges were observed. Abortion of flowers also was recorded. Cultures on potato dextrose agar yielded abundant, gray aerial mycelium and one-celled, hyaline, oblong conidia with obtuse or rounded ends (11.2 to 15.0 × 3.8 to 4.6 μm). Perithecia were scarce (90.2 to 220.0 μm). Asci were not conspicuous, and ascospores measured 10.8 to 23.4 × 3.5 to 7.0 μm. Based on morphological characteristics, the fungus was identified as Glomerella cingulata (anamorph Colletotrichum gloeosporioides) (2). Fruits and leaves of P. edulis with and without wounds were sprayed with a conidial suspension (106/ml) and incubated in plastic bags for 48 h. Lesions similar to original symptoms were observed after 2 weeks only on wounded leaves and fruits. G. cingulata was reisolated, confirming Koch's postulates. This disease has been recorded in Brazil and Japan (1). This is the first report of G. cingulata on passion fruit in Argentina. Reference: (1) E. Francisco Neto et al. Summa Phytopathol. 21:25, 1995. (2) J. A. von Arx. Phytopathol. Z. 29:413, 1957.

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First report of Colletotrichum fructicola and Colletotrichum nymphaeae causing leaf spot on Rubus corchorifolius in Zhejiang province, China

Plant Disease ◽

10.1094/pdis-01-21-0198-pdn ◽

2021 ◽

Author(s):

Ju Wu ◽

Hanrong Wang ◽

Li Fang ◽

Yunye Xie ◽

Lianping Wang

Keyword(s):

Leaf Spot ◽

Type Strain ◽

Disease Incidence ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Zhejiang Province ◽

Colletotrichum Acutatum ◽

Leaf Spot Disease ◽

Conidial Suspension ◽

First Report

Rubus corchorifolius is one of the most economically important fruit trees, (Tian et al. 2021). A severe leaf spot disease on leaves of R. corchorifolius was observed in Longquan county, Zhejiang province (118°42’E, 27°42’N) in 2019, with disease incidence of more than 20% on affected plants. The symptoms on leaves of the naturally affected plants were early necrotic lesion with white centers, surrounded by yellow halos (< 5 mm). Later, lesions were expanded with yellowish-brown centers, surrounded by yellow halos (< 5 mm). Putative pathogenic fungi were isolated as described by Fang (1998) and two pure single-colony fungal strains (FPZ1 and FPZ2) were selected for further analysis. The fungi was cultured on potato dextrose agar (PDA) medium for 6 days, at 25°C. The colonies had gray-green centers, white aerial mycelium and gelatinous orange conidial masses. The conidia were unicellular, smooth-walled, hyaline, cylindrical with obtuse to rounded ends, the size 10.15 to 14.09 µm (mean = 12.95 µm, n = 50) × 4.36 to 6.19 µm (mean = 5.19 µm, n = 50) were single, brown to dark brown, ovoid or irregular in shape, and 5.59 to 12.99 µm (mean = 8.77 µm, n = 50) × 4.68 to 10.36 µm (mean = 6.50 µm, n = 50). The characteristics of FPZ1 were consistent with the description of species in the Colletotrichum gloeosporioides complex (Weir et al. 2012). The conidia of FPZ2 were hyaline, smooth-walled, one-celled, fusiform, the size 9.34 to 14.09 µm (mean = 11.92 µm, n = 50) × 3.26 to 6.15 µm (mean = 4.89 µm, n = 50). Appressoria were single, darker brown, elliptical or irregular in outline, and 4.49 to 15.06 µm (mean = 9.88 µm, n = 50) × 3.23 to 7.42 µm (mean = 5.72 µm, n = 50) in size. The characteristics of FPZ2 were consistent with species of the Colletotrichum acutatum complex (Damn et al. 2012). For molecular identification of strains, the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin (TUB), chitin synthase (CHS-1), and actin (ACT) genes were sequenced (Weir et al. 2012). For the strain FPZ1, the five sequences obtain were deposited in GenBank (MT846907, MT849313, MT849317, MT849315 and MT849319, respectively). A BLAST search of FPZ1 sequences showed 99% identity with the five loci sequences of type strain C. fructicola ICMP 18581 (JX010165, JX010033, JX010405, JX009866 and FJ907426) (Jayawardena et al. 2016). Similarly, for the strain FPZ2, the five sequences (MT846885, MT849314, MT849318, MT849316 and MT849320, respectively) had 99% identity with the five loci sequences of type strain C. nymphaeae CBS 515.78 (JQ948197, JQ948527, JQ949848, JQ948858 and JQ949518, respectively) (Jayawardena et al. 2016). Based on morphological characteristics and phylogenetic analysis, FPZ1 was identified as C. fructicola and FPZ2 as C. nymphaeae, respestively. For pathogenicity tests, 10 μL conidial suspension (1 × 106 conidia per ml) of FPZ1 was used to inoculate five healthy, non-wounded detached leaves, while five leaves inoculated with sterilized water served as control. The experiment was repeated three times, and all leaves were kept on a mist bench at 27°C and relative humidity 80% for 6 days. The inoculation sites of both FPZ1 and FPZ2 became brown and necrotic, while control leaves developed no symptoms. C. fructicola and C. nymphaeae were re-isolated from the lesions of inoculated leaves, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. fructicola and C. nymphaeae causing leaf spot on Rubus corchorifolius in China, and reports on the prevalence of C. gloeosporioides and C. acutatum species complexes will be beneficial to management of anthracnose in R. corchorifolius.

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First Report of Leaf Blight of Basella alba Caused by Alternaria alternata in India

Plant Disease ◽

10.1094/pdis-06-11-0513 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1476-1476 ◽

Cited By ~ 6

Author(s):

N. Ravi Sankar ◽

A. Sreeramulu ◽

D. Sai Gopal ◽

G. Bagyanarayana

Keyword(s):

Alternaria Alternata ◽

Disease Incidence ◽

Morphological Characteristics ◽

Infected Leaf ◽

Conidial Suspension ◽

First Report ◽

Perennial Plant ◽

Basella Alba ◽

Leaf Spots ◽

Severe Infections

Basella alba is a perennial plant of the Basellaceae, native to India, and is distributed widely in the tropics as an ornamental. It is also known as Indian spinach, Ceylon spinach, vine spinach, Malabar spinach or Malabar nightshade and is mostly cultivated as a leafy vegetable or spinach substitute, being rich in vitamin A and C. From 2008 to 2010, severe foliar disease was observed on B. alba in the region of Southern Andhra Pradesh, India. Approximately 75 to 85% of the fields were affected with disease incidence ranging from 70 to 90%. Leaf lesions were elliptical to irregular oval, yellow brown to dark brown, and sometimes concentrically zonate with diffuse margins frequently surrounded by light-colored haloes. Infection often started at the leaf tips and progressed to the base of leaves as symptoms developed. In severe infections, lesions enlarged and coalesced, causing necrosis, wilting, and ultimately death of leaves. Tissues from the margin of infected leaf parts were surface sterilized in 1% sodium hypochlorite for 1 min, plated on potato dextrose agar (PDA), and then incubated at 27°C in the dark for 7 days. Hyphal tips from the margin of each developing colony were subcultured on PDA. Fungal colonies were initially white, becoming olivaceous, and turning brown with age. Conidiophores were brown, short, simple, or sometimes branched. Conidia were obclavate, obpyriform or ellipsoidal with a short conical beak, borne in long chains, branched or unbranched, pale brown to brown, and 18 to 32 μm long and 5 to 14 μm wide at the broadest point. Conidia had three to eight transverse septa and one to two longitudinal septa. On the basis of conidial morphological characteristics, the pathogen was identified as Alternaria alternata (Fr.) Keissler (2). For pathogenicity tests, inoculations were performed on detached, surface sterilized, healthy leaves following the method of Belisario (1). A 5-μl drop of conidial suspension containing 1 × 105 CFU/ml was placed on each leaf and 12 leaves per isolate were used. Leaves were incubated in a growth chamber (90% relative humidity with a 12-h photoperiod). After 7 days, leaf spots that were similar to the original symptoms developed on all inoculated leaves and A. alternata was consistently reisolated from symptomatic leaf tissues on PDA. Control leaves inoculated with sterile distilled water remained asymptomatic. The experiment was performed three times. To our knowledge, this is the first report of A. alternata on B. alba in India. References: (1) A. Belisario et al. Plant Dis. 83:696, 1999. (2) E. G. Simmons. Alternaria: An Identification Manual. The American Phytopathological Society, St. Paul, MN, 2007.

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First Report of Ascochyta Blight of Chickpea in Latin America

Plant Disease ◽

10.1094/pdis.2000.84.1.102c ◽

2000 ◽

Vol 84 (1) ◽

pp. 102-102 ◽

Cited By ~ 10

Author(s):

W. J. Kaiser ◽

F. Coca W. ◽

S. Vega O.

Keyword(s):

Latin America ◽

Ascochyta Blight ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Plant Diseases ◽

Ascochyta Rabiei ◽

Commonwealth Mycological Institute ◽

First Report ◽

Distribution Maps ◽

Santa Rosalia

Chickpea (Cicer arietinum L.) has been cultivated in different regions of Bolivia for hundreds of years. In the highlands (2,400 to 3,000 m above sea level) of the Department (state) of Chuquisaca in southern Bolivia, chickpea is an important cash crop for small farmers. During March through April 1999, a blight was observed infecting local chickpea landraces in Chamicle, Escana, Kullpa Ckasa, Presto, Q'ara Puncu, Santa Rosalia, Sucre, and Yotala in Chuquisaca, and its cause was tentatively identified as Ascochyta rabiei (Pass.) Labrousse (teleomorph Didymella rabiei (Kovachevski) v. Arx) based on disease symptomatology. Stems, leaflets, and pods of infected plants exhibited abundant necrotic lesions. Isolations were made from lesions on leaflets, stems, pods, and seeds of infected plants on 2% water agar and potato dextrose agar. The fungus was isolated from the foliar and reproductive tissues of infected plants. Koch's postulates were fulfilled by inoculating the foliage of 15-day-old seedlings of a local chickpea landrace with spore suspensions of three isolates of the pathogen from Escana, Santa Rosalia, and Sucre. Inoculated and control (sterile water) plants were incubated in moist chambers for 4 days in the laboratory at ambient temperatures and under natural daylight. The fungus was reisolated from lesions that developed on the leaflets, petioles, and stems of all inoculated seedlings but not from tissues on any of the noninoculated control plants. The fungus was identified as A. rabiei based on symptoms, cultural and morphological characteristics (2), and pathogenicity tests. Above average rainfall and cool weather during March and April favored development and spread of the disease in many chickpea-growing areas. Severe infection usually resulted in dieback and death of plants and reduced yields. Additionally, A. rabiei was isolated from chickpea seeds purchased in the markets of Sucre and Monteagudo and in seeds used by farmers in Escana to plant the 1999 crop (which had supplied the plants previously observed with blight). The teleomorph did not develop on naturally infested chickpea debris from five locations when incubated over the winter on the soil surface in Sucre. Based on farmers' reports, it appears that Ascochyta blight of chickpea has been present in the Department of Chuquisaca and possibly other Bolivian departments for many years. This is the first report of the disease in either Bolivia or other countries of Latin America (Mexico and Central and South America) (1). References: (1) CAB. 1991. CAB Distribution Maps of Plant Diseases: Ascochyta rabiei. Map No. 151. CAB International Mycological Institute, Wallingford, England. (2) E. Punithalingham and P. Holliday. 1972. Ascochyta rabiei. Descriptions of Pathogenic Fungi and Bacteria No. 337. Commonwealth Mycological Institute, Kew, England.

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First Report of Ascochyta Blight of Vicia hirsuta (Hairy Tare) in the Republic of Georgia Caused by Ascochyta sp

Plant Disease ◽

10.1094/pd-90-1555a ◽

2006 ◽

Vol 90 (12) ◽

pp. 1555-1555 ◽

Cited By ~ 1

Author(s):

M. I. Chilvers ◽

T. L. Horton ◽

T. L. Peever ◽

W. J. Kaiser ◽

F. J. Muehlbauer

Keyword(s):

Sequence Similarity ◽

Ascochyta Blight ◽

Pathogenic Fungi ◽

Ascochyta Rabiei ◽

Morphological Identification ◽

Conidial Suspension ◽

Republic Of Georgia ◽

First Report ◽

Vicia Hirsuta ◽

The Republic

Tan lesions with dark margins containing concentric rings of black pycnidia were observed on leaves and pods of hairy tare (Vicia hirsuta L.) growing near Ateni, GA (41°54.631′N, 44°05.586′E, elev. 730 m) on 1 July 2004. Lesions were reminiscent of those induced by Ascochyta rabiei (Pass.) Labrousse on chickpea (Cicer arietinum L.). At the time of collection, necrotic lesions were observed on the stems, leaflets, and pods of several plants. The fungus was isolated by surface-disinfecting small pieces of infected tissue in 95% EtOH for 10 s, 1% NaOCl for 1 min, and then deionized H20 for 1 min. Tissue pieces were placed on 3% water agar (WA) for 24 h under fluorescent lights with a 12-h photoperiod to induce sporulation. Single-conidial isolations were made by streaking cirrhi on 3% WA and picking germinated single conidia. After 14 days of growth, the isolated fungus had colony morphology similar to that of A. rabiei on V8 juice agar. A conidial suspension of the fungus (1 × 105 conidia/ml) was spray-inoculated onto 2-week-old plants including PI lines 628303, 628304, 420171, and 422499 of V. hirsuta and C. arietinum cv. Burpee. Plants were obtained from the USDA Western Region Plant Introduction Station, Pullman, WA, and 20 replicate plants of each genotype were inoculated. Inoculated plants were covered with a plastic cup to maintain high humidity and incubated in a growth chamber for 48 h at 18°C. Following removal of the cups, characteristic Ascochyta blight lesions were apparent 14 days after inoculation on both plant species. DNA was extracted from the isolate and 610 bp of the glyceraldehyde-3-phosphate-dehydrogenase gene (G3PD), 364 bp of the chitin synthase 1 gene, and 330 bp of the translation elongation factor 1-alpha gene were amplified with gpd-1 and gpd-2 primers (1), CHS-79 and CHS-354 primers (2), and EF1-728F and EF1-986R primers (2), respectively. Amplicons were direct sequenced on both strands and a BLAST search of the NCBI nucleotide database with consensus G3PD, CHS, and EF sequences revealed the chickpea pathogen Didymella rabiei (anamorph Ascochyta rabiei) accessions DQ383958, DQ386480, and DQ386488 as the closest matches in the databases with 95, 95, and 88% sequence similarity, respectively. These results, coupled with the morphological identification and the inoculation results, confirm the identity of the fungus as Ascochyta sp. Further research needs to be performed to determine if this represents a new species of Ascochyta. The identification of this fungus is part of a larger project to develop a phylogeny for Ascochyta spp. infecting cultivated legumes and their wild relatives that will provide a framework for the study of the evolution of host specificity and speciation of plant-pathogenic fungi. This is the second report of an Ascochyta species on V. hirsuta, and to our knowledge, the first report of Ascochyta blight of this host in the Republic of Georgia. References: (1) M. L. Berbee et al. Mycologia 91:964, 1999. (2) I. Carbone and L. M. Kohn. Mycologia 91:553, 1999.

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First report of banana (Musa acuminate L. AAA Cavendish, cv. Formosana) leaf spot disease caused by Curvularia geniculata in China

Plant Disease ◽

10.1094/pdis-09-21-2001-pdn ◽

2021 ◽

Author(s):

Yanxiang Qi ◽

Yanping Fu ◽

Jun Peng ◽

Fanyun Zeng ◽

Yanwei Wang ◽

...

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Universal Primers ◽

Leaf Spot Disease ◽

Leaf Margin ◽

Conidial Suspension ◽

Tropical Fruit ◽

First Report ◽

Spot Disease

Banana (Musa acuminate L.) is an important tropical fruit in China. During 2019-2020, a new leaf spot disease was observed on banana (M. acuminate L. AAA Cavendish, cv. Formosana) at two orchards of Chengmai county (19°48ʹ41.79″ N, 109°58ʹ44.95″ E), Hainan province, China. In total, the disease incidence was about 5% of banana trees (6 000 trees). The leaf spots occurred sporadically and were mostly confined to the leaf margin, and the percentage of the leaf area covered by lesions was less than 1%. Symptoms on the leaves were initially reddish brown spots that gradually expanded to ovoid-shaped lesions and eventually become necrotic, dry, and gray with a yellow halo. The conidia obtained from leaf lesions were brown, erect or curved, fusiform or elliptical, 3 to 4 septa with dimensions of 13.75 to 31.39 µm × 5.91 to 13.35 µm (avg. 22.39 × 8.83 µm). The cells of both ends were small and hyaline while the middle cells were larger and darker (Zhang et al. 2010). Morphological characteristics of the conidia matched the description of Curvularia geniculata (Tracy & Earle) Boedijn. To acquire the pathogen, tissue pieces (15 mm2) of symptomatic leaves were surface disinfected in 70% ethanol (10 s) and 0.8% NaClO (2 min), rinsed in sterile water three times, and transferred to potato dextrose agar (PDA) for three days at 28°C. Grayish green fungal colonies appeared, and then turned fluffy with grey and white aerial mycelium with age. Two representative isolates (CATAS-CG01 and CATAS-CG92) of single-spore cultures were selected for molecular identification. Genomic DNA was extracted from the two isolates, the internal transcribed spacer (ITS), large subunit ribosomal DNA (LSU rDNA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II second largest subunit (RPB2) were amplified and sequenced with universal primers ITS1/ITS4, LROR/LR5, GPD1/GPD2, EF1-983F/EF1-2218R and 5F2/7cR, respectively (Huang et al. 2017; Raza et al. 2019). The sequences were deposited in GenBank (MW186196, MW186197, OK091651, OK721009 and OK491081 for CATAS-CG01; MZ734453, MZ734465, OK091652, OK721100 and OK642748 for CATAS-CG92, respectively). For phylogenetic analysis, MEGA7.0 (Kumar et al. 2016) was used to construct a Maximum Likelihood (ML) tree with 1 000 bootstrap replicates, based on a concatenation alignment of five gene sequences of the two isolates in this study as well as sequences of other Curvularia species obtained from GenBank. The cluster analysis revealed that isolates CATAS-CG01 and CATAS-CG92 were C. geniculata. Pathogenicity assays were conducted on 7-leaf-old banana seedlings. Two leaves from potted plants were stab inoculated by puncturing into 1-mm using a sterilized needle and placing 10 μl conidial suspension (2×106 conidia/ml) on the surface of wounded leaves and equal number of leaves were inoculated with sterile distilled water serving as control (three replicates). Inoculated plants were grown in the greenhouse (12 h/12 h light/dark, 28°C, 90% relative humidity). Necrotic lesions on inoculated leaves appeared seven days after inoculation, whereas control leaves remained healthy. The fungus was recovered from inoculated leaves, and its taxonomy was confirmed morphologically and molecularly, fulfilling Koch’s postulates. C. geniculata has been reported to cause leaf spot on banana in Jamaica (Meredith, 1963). To our knowledge, this is the first report of C. geniculata on banana in China.

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First Report of Leaf Blight Caused by Septoria allii on Garlic Chives in Korea

Plant Disease ◽

10.1094/pdis-08-12-0809-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 147-147

Author(s):

J. H. Park ◽

S. E. Cho ◽

K. S. Han ◽

H. D. Shin

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Leaf Blight ◽

Plant Diseases ◽

Cultivated Plants ◽

Sequence Information ◽

Conidial Suspension ◽

Korean Society ◽

First Report

Garlic chives, Allium tuberosum Roth., are widely cultivated in Asia and are the fourth most important Allium crop in Korea. In June 2011, a leaf blight of garlic chives associated with a Septoria spp. was observed on an organic farm in Hongcheon County, Korea. Similar symptoms were also found in fields within Samcheok City and Yangku County of Korea during the 2011 and 2012 seasons. Disease incidence (percentage of plants affected) was 5 to 10% in organic farms surveyed. Diseased voucher specimens (n = 5) were deposited at the Korea University Herbarium (KUS). The disease first appeared as yellowish specks on leaves, expanding to cause a leaf tip dieback. Half of the leaves may be diseased within a week, especially during wet weather. Pycnidia were directly observed in leaf lesions. Pycnidia were amphigenous, but mostly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, separate, unilocular, 50 to 150 μm in diameter, with ostioles of 20 to 40 μm in diameter. Conidia were acicular, straight to sub-straight, truncate at the base, obtuse at the apex, hyaline, aguttulate, 22 to 44 × 1.8 to 3 μm, mostly 3-septate, occasionally 1- or 2-septate. These morphological characteristics matched those of Septoria allii Moesz, which is differentiated from S. alliacea on conidial dimensions (50 to 60 μm long) (1,2). A monoconidial isolate was cultured on potato dextrose agar (PDA). Two isolates have been deposited in the Korean Agricultural Culture Collection (Accession Nos. KACC46119 and 46688). 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 482-bp was deposited in GenBank (JX531648 and JX531649). ITS sequence information was at least 99% similar to those of many Septoria species, however no information was available for S. allii. 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 PDA. Control leaves were sprayed with sterile water. The plants were placed in humid chambers (relative humidity 100%) for the first 48 h. After 7 days, typical leaf blight symptoms started to develop on the leaves of inoculated plants. S. allii was reisolated from the lesions of inoculated plants, confirming Koch's postulates. No symptoms were observed on control plants. The host-parasite association of A. tuberosum and S. allii has been known only from China (1). S. alliacea has been recorded on several species of Allium, e.g. A. cepa, A. chinense, A. fistulosum, and A. tuberosum from Japan (4) and A. cepa from Korea (3). To the best of our knowledge, this is the first report of S. allii on garlic chives. No diseased plants were observed in commercial fields of garlic chives which involved regular application of fungicides. The disease therefore seems to be limited to organic garlic chive production. References: (1) P. K. Chi et al. Fungous Diseases on Cultivated Plants of Jilin Province, Science Press, Beijing, China, 1966. (2) P. A. Saccardo. Sylloge Fungorum Omnium Hucusque Congnitorum. XXV. Berlin, 1931. (3) The Korean Society of Plant Pathology. List of Plant Diseases in Korea, Suwon, Korea, 2009. (4) The Phytopathological Society of Japan. Common Names of Plant Diseases in Japan, Tokyo, Japan, 2000.

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First Report on Ovate-leaf Atractylodes Damping-off Caused by Fusarium oxysporum species Complex in South Korea

Plant Disease ◽

10.1094/pdis-05-21-1107-pdn ◽

2021 ◽

Author(s):

Oliul Hassan ◽

Taehyun Chang

Keyword(s):

South Korea ◽

Fusarium Oxysporum ◽

Species Complex ◽

Disease Incidence ◽

Fusarium Species ◽

Morphological Characteristics ◽

Conidial Suspension ◽

Sterile Water ◽

Damping Off ◽

First Report

In South Korea, ovate-leaf atractylodes (OLA) (Atractylodes ovata) is cultivated for herbal medicine. During May to June 2019, a disease with damping off symptoms on OLA seedlings were observed at three farmer fields in Mungyeong, South Korea. Disease incidence was estimated as approximately 20% based on calculating the proportion of symptomatic seedlings in three randomly selected fields. Six randomly selected seedlings (two from each field) showing damping off symptoms were collected. Small pieces (1 cm2) were cut from infected roots, surface-sterilized (1 minute in 0.5% sodium hypochlorite), rinsed twice with sterile water, air-dried and then plated on potato dextrose agar (PDA, Difco, and Becton Dickinson). Hyphal tips were excised and transferred to fresh PDA. Six morphologically similar isolates were obtained from six samples. Seven-day-old colonies, incubated at 25 °C in the dark on PDA, were whitish with light purple mycelia on the upper side and white with light purple at the center on the reverse side. Macroconidia were 3–5 septate, curved, both ends were pointed, and were 19.8–36.62 × 3.3–4.7 µm (n= 30). Microconidia were cylindrical or ellipsoid and 5.5–11.6 × 2.5–3.8 µm (n=30). Chlamydospores were globose and 9.6 –16.3 × 9.4 – 15.0 µm (n=30). The morphological characteristics of present isolates were comparable with that of Fusarium species (Maryani et al. 2019). Genomic DNA was extracted from 4 days old cultures of each isolate of SRRM 4.2, SRRH3, and SRRH5, EF-1α and rpb2 region were amplified using EF792 + EF829, and RPB2-5f2 + RPB2-7cr primer sets, respectively (Carbone and Kohn, 1999; O'Donnell et al. 2010) and sequenced (GenBank accession number: LC569791- LC569793 and LC600806- LC600808). BLAST query against Fusarium loci sampled and multilocus sequence typing database revealed that 99–100% identity to corresponding sequences of the F. oxysporum species complex (strain NRRL 28395 and 26379). Maximum likelihood phylogenetic analysis with MEGA v. 6.0 using the concatenated sequencing data for EF-1α and rpb2 showed that the isolates belonged to F. oxysporum species complex. Each three healthy seedlings with similar sized (big flower sabju) were grown for 20 days in a plastic pot containing autoclaved peat soil was used for pathogenicity tests. Conidial suspensions (106 conidia mL−1) of 20 days old colonies per isolate (two isolates) were prepared in sterile water. Three pots per strain were inoculated either by pouring 50 ml of the conidial suspension or by the same quantity of sterile distilled water as control. After inoculation, all pots were incubated at 25 °C with a 16-hour light/8-hour dark cycle in a growth chamber. This experiment repeated twice. Inoculated seedlings were watered twice a week. Approximately 60% of the inoculated seedlings per strain wilted after 15 days of inoculation and control seedlings remained asymptomatic. Fusarium oxysporum was successfully isolated from infected seedling and identified based on morphology and EF-1α sequences data to confirm Koch’s postulates. Fusarium oxysporum is responsible for damping-off of many plant species, including larch, tomato, melon, bean, banana, cotton, chickpea, and Arabidopsis thaliana (Fourie et al. 2011; Hassan et al.2019). To the best of our knowledge, this is the first report on damping-off of ovate-leaf atractylodes caused by F. oxysporum in South Korea. This finding provides a basis for studying the epidemic and management of the disease.

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First Report of Stem and Foliar Blight of Sunflower Caused by Alternariaster helianthi in Louisiana

Plant Disease ◽

10.1094/pdis-01-12-0107-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 761-761 ◽

Cited By ~ 1

Author(s):

R. Singh ◽

D. M. Ferrin

Keyword(s):

Disease Incidence ◽

Fluorescent Light ◽

Infected Leaf ◽

Stem Tissue ◽

First Report ◽

Foliar Blight ◽

Leaf Spots ◽

Plastic Bags ◽

Alternaria Helianthi ◽

Stem Lesions

During the fall of 2009, sunflower (Helianthus annuus L.) planted at the LSU AgCenter's Burden Center in Baton Rouge, LA exhibited severe stem and foliar blight symptoms. Symptoms on stems and petioles included elongated, slightly sunken lesions with dark brown margins. Leaf symptoms included irregular to circular, dark brown lesions with white centers and surrounded by a yellow halo. Several spots often coalesced to form large, blighted areas, and severely affected leaves turned yellow, followed by defoliation. The corolla and calyx exhibited similar lesions except for the yellow halo. Disease developed rapidly and the whole (100% disease incidence) field was blighted within a week following a rain (4 mm). Infected leaf and stem tissue was surface disinfested and plated on ¼-strength potato dextrose agar (PDA). Both leaf and stem tissue consistently produced dark olivaceous-to-black fungal colonies at room temperature under 12 h of fluorescent light per day. Conidia were 53 to 128 × 10 to 26 μm, borne singly on the conidiophores, hyaline to dark olivaceous, cylindrical, rounded at both ends, and with 6 to 10 transverse and 0 to 2 longitudinal septa. Conidiophores were single, unbranched, septate, hyaline to dark olivaceous, and measured 77 to 128 × 7 to 13 μm. Morphologically, the fungus was identified as Alternariaster helianthi (Hansf.) E.G. Simmons (= Alternaria helianthi [Hansf.] Tubaki & Nishih) (1). A single-spore isolate (PDC-4291) was obtained from the original culture and DNA from this isolate was extracted with a DNeasy Plant Mini Kit (Qiagen Inc., Valencia, CA). Primers ITS1 and ITS4 were used to amplify and sequence the internal transcribed spacer regions 1 and 2, and NCBI blast analysis of the 552-bp sequence (GenBank Accession No. JN208925) resulted in 100% homology with Alternaria helianthi isolated from sunflower infected with leaf spot and blight disease in India (GenBank Accession No. DQ156343). Pathogenicity was determined by inoculating 20 potted sunflower plants (Full Sun Improved TD, Fred C. Gloeckner and Company, Inc., Harrison, NY) with conidia from a 2-week-old culture of isolate PDC-4291. Each plant was sprayed with 25 ml of suspension containing 106 conidia/ml. Twenty control plants were sprayed with 25 ml of sterile distilled water. Inoculated and control plants were covered with plastic bags and maintained in a greenhouse at 28 ± 2°C. Plastic bags were removed 72 h after inoculation. Leaf spots similar to the original symptoms appeared on all 20 inoculated plants 5 days after inoculation. A few stem lesions were observed on 13 plants. Two weeks after inoculation, infected leaves turned yellow and blighted. Alternariaster helianthi (= Alternaria helianthi) was reisolated from the leaf spots and stem lesions. No symptoms developed on any of the 20 control plants. On the basis of morphology and sequence data, this pathogen was identified as A. helianthi, and to our knowledge, this is the first report of sunflower stem and foliar blight caused by A. helianthi in Louisiana. In Louisiana, sunflower is a popular ornamental that is grown in landscapes and gardens and by commercial flower growers who grow it for cut flower arrangements. Louisiana's hot, humid weather is ideal for disease development, which may discourage gardeners and commercial growers from planting sunflower. Reference: (1) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Center, Utrecht, the Netherlands, 2007.

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