scholarly journals First Report of Peronospora parasitica on Wild Rocket (Diplotaxis tenuifolia) in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (12) ◽  
pp. 1381-1381 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
New York ◽  
Downy Mildew ◽  
Causal Agent ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Peronospora Parasitica ◽  
First Report ◽  
Downy Mildews ◽  
Air Temperatures ◽  
Wild Rocket

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild rocket, are now widely cultivated in Italy. Wild rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. During the fall of 2002, a foliar disease of D. tenuifolia was observed in the field or greenhouse on several commercial farms in the Liguria Region of northern Italy. Symptoms appeared as small, irregular, dark brown-to-black speckling on the adaxial surfaces of leaves. The speckled areas sometimes expanded into larger spots. These symptoms were followed by leaf yellowing and the appearance of sporangiophores and sporangia on the lower and upper leaf surfaces. Sporangiophores were dichotomously branched with slender curved tips. Sporangia were ovoid, measuring 20 to 28 (average 22) μm long and 15 to 25 (average 19) μm wide. The causal agent of the disease was identified as Peronospora parasitica (3). Pathogenicity was established by inoculating 10 30-day-old plants of D. tenuifolia grown in pots in a peat/pumice/clay/composted bark mix (60:20:10:10), with a conidial suspension (102 conidia per ml). Ten noninoculated plants maintained under the same conditions served as the control. Plants were maintained in a glasshouse at air temperatures ranging between 10 and 26°C (average 16°C) and relative humidity at 85%. The pathogenicity test was done twice. Downy mildew symptoms developed within 12 days, and the same fungus was observed on inoculated plants. Noninoculated plants did not develop symptoms. To our knowledge, this is the first report of P. parasitica on D. tenuifolia in Italy. P. parasitca has been reported as the causal agent of downy mildew on D. muralis in England (1) and on cultivated rocket (Eruca sativa) in California (2). References: (1) J. Fraymouth. Trans. Br. Mycol. Soc. 39:79, 1956. (2) S. T. Koike. Plant Dis. 82:1063, 1998. (3) D. M. Spencer. The Downy Mildews. Academic Press. New York, 1981.

scholarly journals First Report of Downy Mildew Caused by Peronospora parasitica on Iberis sempervirens in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1261-1261
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
New York ◽  
Downy Mildew ◽  
Morphological Characteristics ◽  
Sprinkler Irrigation ◽  
The United States ◽  
Plant Diseases ◽  
Pathogenicity Test ◽  
Peronospora Parasitica ◽  
First Report ◽  
Downy Mildews

Iberis sempervirens (evergreen candytuft) is a garden species belonging to the Brassicaceae family. During June 2004, a damaging foliar disease was observed in several commercial farms near Albenga (northern Italy) on I. sempervirens plants grown outdoors in containers. More than 30% of the plants were affected. Symptoms appeared on both sides of leaves, buds, flowers, and fruits. Initially, leaves were slightly chlorotic, but within 5 to 7 days a characteristic whitish furry growth developed on the lower and upper leaf surfaces. The efflorescence was particularly evident on the lower surfaces of leaves and consisted of sporangiophores and sporangia. The appearance and severity of the disease increased because of overhead sprinkler irrigation. Microscopic observations revealed dichotomously branched sporangiophores with slender curved tips. Sporangiophores with a length of 115 to 410 μm (average 295 μm) ended with sterigmata bearing single sporangia. Sporangia were ovoid and measured 18 to 28 × 25 to 45 μm (average 22 × 35 μm). The pathogen was identified as Peronospora parasitica on the basis of its morphological characteristics (3). Pathogenicity was confirmed by inoculating leaves of 10 45-day-old healthy plants grown in 14-cm-diameter pots with a sporangial suspension (1 × 103 conidia/ml). Ten noninoculated plants served as controls. Plants were maintained outdoors at 50% light intensity with temperatures ranging between 16 and 25°C (average 18°C) and 85 to 100% relative humidity. The pathogenicity test was carried out twice. After 18 days, typical symptoms of downy mildew developed on the inoculated plants and P. parasitica was observed on the leaves. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of P. parasitica on evergreen candytuft in Italy. P. parasitica was previously reported on I. sempervirens in the United Kingdom (1) and on I. amara in California (2). Voucher specimens are available at the AGROINNOVA Collection, University of Torino, Italy. References: (1) S. Francis and G. Waterhouse. Trans. Br. Mycol. Soc. 91:1, 1988. (2) P. R. Muller et al. Index of Plant Diseases in the United States. USDA Handbook No. 165, 1960. (3) D. M. Spencer. The Downy Mildews. Academic Press, New York, 1981.

scholarly journals First Report of Colletotrichum boninense Causing Anthracnose on Pepper in China

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 138-138 ◽  
Author(s):  
Y. Z. Diao ◽  
J. R. Fan ◽  
Z. W. Wang ◽  
X. L. Liu
Keyword(s):  
Internal Transcribed Spacer ◽  
Severe Disease ◽  
Causal Agent ◽  
Its Sequences ◽  
Universal Primers ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Species Specific

Anthracnose, caused by Colletotrichum spp., is a severe disease and results in large losses in pepper (Capsicum frutescens) production in China (4). Colletotrichum boninense is one of the Colletotrichum species in pepper in China. In August 2011, anthracnose symptoms (circular, sunken lesions with orange to black spore masses) were observed on pepper fruits in De-Yang, Sichuan Province, China. Three single-spore isolates (SC-6-1, SC-6-2, SC-6-3) were obtained from the infected fruits. A 5-mm diameter plug was transferred to potato dextrose agar (PDA); the isolates formed colonies with white margins and circular, dull orange centers. The conidia were cylindrical, obtuse at both ends, and 10.5 to 12.6 × 4.1 to 5.0 μm. The colonies grew rapidly at 25 to 28°C, and the average colony diameter was 51 to 52 mm after 5 days on PDA at 25°C. Based upon these characters, the causal agent was identified as C. boninense. To confirm the identity of the isolates, the internal transcribed spacer (ITS) regions were amplified with the ITS1/ITS4 universal primers (1). The internal transcribed spacer (ITS) sequences (Accession No. JQ926743) of the causal fungus shared 99 to 100% homology with ITS sequences of C. boninense in GenBank (Accession Nos. FN566865 and EU822801). The identity of the causal agent as C. boninense was also confirmed by species-specific primers (Col1/ITS4) (2). In a pathogenicity test, five detached ripe pepper fruits were inoculated with 1 μl of a conidial suspension (106 conidia/mL) or five fruits with 1 μl of sterile water were kept as control. After 7 days in a moist chamber at 25°C, typical anthracnose symptoms had developed on the five inoculated fruits but not on control fruits. C. boninense was reisolated from the lesions, and which was confirmed by morphology and molecular methods as before. There have reports of C. boninense infecting many species of plants, including pepper (3). To our knowledge, this is the first report of C. boninense causing anthracnose on pepper in China. References: (1) A. K. Lucia et al. Phytopathology 93:581, 2002. (2) S. A. Pileggi et al. Can. J. Microbiol. 55:1081, 2009. (3) H. J. Tozze et al. Plant Dis. 93:106, 2009. (4) M. L. Zhang. J. Anhui Agri. Sci. 2:21, 2000.

scholarly journals First Report of Colletotrichum aenigma Causing Anthracnose of Grape in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Ju Sung Kim ◽  
Oliul Hassan ◽  
Taehyun Chang
Keyword(s):  
South Korea ◽  
Disease Incidence ◽  
Juglans Regia ◽  
Morphological Characteristics ◽  
Causal Agent ◽  
Effective Control ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
First Report ◽  
Colletotrichum Species

Grape (cv. Kyoho) is one of the most popular dessert fruits in South Korea. Anthracnose caused by Colletotrichum species is a common and very destructive disease of grape in the country. In 2019, severe outbreaks of anthracnose was observed in different grape orchards in Gimcheon (36º09´N, 128º00´ E), South Korea. The disease incidence on fruit was up to 50% in the orchards with most severe outbreaks and infected fruit displayed typical anthracnose symptoms including sunken necrotic lesions with orange-like conidial mass. For isolation of putative causal agents, nine diseased fruits were collected from three commercial orchards. A total of nineisolates were made from nine of the infected fruit by spreading spore masses (1x106 conidia mL-1) from each fruit on water agar and collecting single germinated spores after incubation at 25 ºC overnigh. The single germinated spores were transferred on to fresh potato dextrose agar (PDA) (Difco, Becton Dickinson) and incubated at 25ºC in the dark. Seven day old colonies were cottony white on the upper side and gray at the center on the reverse side. Conidia were cylindrical with round ends and measured 13.9 – 20.1 × 5.4 – 8.1 μm (mean = 16.5 × 6.6 μm, n = 30). Appressoria were brownish, sub-cylindrical with a few lobes and 10.3 –16.7 × 6.6 – 10.9 μm (mean = 13.1 × 8.1 μm, n = 30). The morphological characteristics of the solates resembled those of Colletotrichum species within the C. gloeosporioides complex (Weir et al. 2012). DNA was amplified using the following primer pairs: ITS1/ITS4, GDF / GDR, ACT-512F / ACT-783R, Bt2a/ Bt2b, and CHS79-F/CHS-354R (Weir et al. 2012). Accession numbers, LC586811 to LC586825 were obtained after depositing all the resulting sequences in GenBank. A 50% majority rules phylogenetic tree (Bayesian phylogenic analysis) was constructed based on concatenated sequences of ITS, GAPDH, ACT, TUB, and CHS using MrBayes 3.2.10. The present isolates formed a single clade with the reference isolates of C. aenigma (isolate ICMP 18608 and ICMP 18686). For a pathogenicity test, healthy grapefruits were collected from an orchards, surface sterilized by dipping in 1% sodium hypochlorite, rinsed with sterilized water and dried by blotting. A conidial suspension (1×106 conidia mL-1) in sterilized water were prepared from one week old colonies of isolates GRAP10 and GRAP12. A small wound was made on sterilized detached fruit by punching with a sterile pin. A drop of the conidial suspension was placed on the wound, while the control fruit received a drop of sterile water. Similarly, unwounded fruit were also inoculated with a single droplet of conidial suspension. For each isolate and method (wounded and unwounded), ten fruit were inoculated, and ten non-inoculated fruit were used as control. All the treated fruit were kept in a plastic box containing moist tissue and incubated at 25º C in the dark. Typical anthracnose lesions appeared on all inoculated wounded fruit while non-inoculated and inoculated unwounded fruits remained asymptotic. Koch postulates were fulfilled by re-isolating and re-identifying the causal agent from inoculated fruit. Colletotrichum aenigma has been reported as the causal agent of anthracnose on Juglans regia, Camellia sinensis and Actinidia arguta in China (Weir et al. 2012; Wang et al. 2016; Wang et al. 2018). Previous studies reported four Colletotrichum species (C. acutatum, C. gloeosporioides, C. fructicola, and C. viniferum) to cause this disease on grapes in South Korea (Oo and Oh 2017; Lim et al. 2020). To the best of our knowledge, this is the first report on grape anthracnose caused by C. aenigma in South Korea. This finding may help to take effective control measures of this disease.

scholarly journals First Report of Colletotrichum cereale Causing Anthracnose on Avena nuda in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Na Zhao ◽  
Junyu Yang ◽  
Xiaoli Fang ◽  
lingrui Li ◽  
Hongfei Yan ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Causal Agent ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Fungal Isolates ◽  
Colletotrichum Cereale ◽  
Avena Nuda

Naked oats (Avena nuda L.) is rich in protein, fat, vitamin, mineral elements and so on, and is one of the world's recognized cereal crops with the highest nutritional and healthcare value. In July 2019, leaf spot was detected on A. nuda in Zhangbei experimental station of Hebei Agricultural University. The incidence of disease is 10% to 20%. The symptoms were similar to anthracnose disease, the infected leaves had fusiform or nearly fusiform yellowish-brown spots, yellow halo around the spots. Numerous acervuli with black setae diagnostic of fungi in the genus Colletotrichum were present on necrotic lesions. To identify the pathogen, ten symptomatic leaves were collected, and only one disease spot was isolated from each leaf. Small square leaf pieces (3 to 5 mm) were excised from the junction of diseased and healthy tissues with a sterile scalpel and surface disinfested with 75% alcohol for 30s, 0.1% corrosive sublimate for 1 min, rinsed three times in sterile water. Plant tissues were then transferred on potato dextrose agar (PDA), and incubated at 25°C for 7 days. Two fungal isolates were obtained and purified by single-spore isolation method. All fungi have the same morphology and no other fungi were isolated. The aerial mycelium was gray black. The conidia were colorless and transparent, falcate, slightly curved, tapered toward the tips, and produced in acervuli with brown setae. The length and width of 100 conidia were measured and size ranged from 1.86 to 3.84 × 8.62 to 29.81 μm. These morphological characteristics were consistent with the description of Colletotrichum cereale (Crouch et al. 2006). To further assess the identity of the species, the genomic DNA of two fungal isolates (LYM19-4 and LYM19-10) was extracted by a CTAB protocol. The ribosomal DNA internal transcribed spacer (ITS) region as well as, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and the beta-tubulin 2 (Tub2) partial genes were amplified and sequenced with primers ITS4/5, GDF/GDR, ACT-512F/ACT-783R, and T1/Bt2b, respectively (Carbone et al. 1999; Templeton et al. 1992; O'Donnell et al. 1997; Glass et al. 1995). The sequences of the ITS-rDNA region (MW040121, MW040122), the GAPDH sequences (MW052554, MW052555), the ACT sequences (MW052556, MW052551) and the Tub2 sequences (MW052552, MW052553) of the two single-spore isolates were more than 99% identical to C. cereale isolate CGMCC3.15110 (JX625159, KC843517, KC843534 and JX625186). Maximum likelihood tree based on concatenated sequences of the four genes were constructed using MEGA7. The results showed the strains isolated from A. nuda were closely related to C. cereale, as supported by high bootstrap values. A pathogenicity test of the C. cereale isolates was performed on first unfolding leaves of A. nuda. Koch's postulates were carried out with isolates by spraying a conidial suspension of 106 conidia/mL on leaves of healthy A. nuda. Four replicated pots were inoculated at a time, 10 leaves each pot, while sterile distilled water was used as the control. All treated plants were placed in a moist chamber (25°C, 16-h light and 8-h dark period). Anthracnose symptoms developed on the inoculated plants 7 days post inoculation while all control plants remained healthy. Microscopic examination showed the surface of infected leaves had the same acervuli, setae, and conidia as the original isolate. The pathogenicity test was repeated three times. C. cereale was previously reported as the causal agent of anthracnose on feather reed grass in US (Crouch et al. 2009). To our knowledge, this is the first report of C. cereale as the causal agent of A. nuda anthracnose in China.

scholarly journals First Report of Downy Mildew on Basil (Ocimum basilicum) in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 312-312 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
G. Minuto ◽  
M. L. Gullino
Keyword(s):  
Relative Humidity ◽  
Downy Mildew ◽  
Morphological Characteristics ◽  
Ocimum Basilicum ◽  
Central Vein ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
First Report ◽  
Sweet Basil ◽  
Mediterranean Countries

Sweet basil (Ocimum basilicum) is an economically important herb in several Mediterranean countries. Approximately 80 ha are grown annually in Italy for fresh and processed consumption. In 2003, a damaging foliar disease was observed in several greenhouses located in the Liguria Region of northern Italy. More that 50% of the plants were affected. Leaves of infected plants were initially slightly chlorotic, especially near the central vein. Within 2 to 3 days, a characteristic gray, furry growth was evident on the lower surface of infected leaves. These symptoms sometimes occurred on the top sides of leaves. Although the distribution of the disease was generally uniform, symptoms appeared first in a patchy pattern in the central part of the greenhouses where air temperature and relative humidity were highest. Where air circulation was apparently poor, bottom leaves were severely affected by the disease. Microscopic observations revealed conidiophores branching two to seven times. Conidiophores with a length of 250 to 500 μm (average 350 μm) ended with sterigmata bearing single conidia. Conidia measured 15 to 25 × 20 to 35 μm (average 22 × 28 μm) and were elliptical and grayish in mass. The pathogen was identified as a Peronospora sp. based on its morphological characteristics (3). Pathogenicity was confirmed by inoculating leaves of 40-day-old healthy plants with a conidial suspension (1 × 105 conidia per ml). Three containers containing 150 plants each of O. basilicum cv. Genovese gigante were used as replicates. Noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a growth chamber at 20°C (12 h of light per day) and 90 to 95% relative humidity. The pathogenicity test was carried out twice. After 6 days, typical symptoms of downy mildew developed on the inoculated plants and a Peronospora sp. was observed on the leaves. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of a Peronospora sp. on basil in Italy. Peronospora sp. and P. lamii were previously reported on sweet basil in Uganda (1,2). References: (1) C. G. Hansford. Rev. Appl. Mycol. 12:421, 1933. (2) C. G. Hansford. Rev. Appl. Mycol. 17:345, 1938. (3) D. M. Spencer. The Downy Mildews. Academic Press, N.Y., 1978.

scholarly journals First Report of Leptosphaeria biglobosa ‘brassicae’ Causing Blackleg on Brassica juncea var. multisecta in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yuexuan Long ◽  
Mingxue Shang ◽  
Yue Deng ◽  
Chuan Yu ◽  
Mingde Wu ◽  
...  
Keyword(s):  
Brassica Juncea ◽  
Yellow Pigment ◽  
Causal Agent ◽  
Control Group ◽  
Conidial Suspension ◽  
First Report ◽  
Fungal Isolates ◽  
Dna Fragment ◽  
Leptosphaeria Biglobosa ◽  
Β Tubulin

Brassica juncea var. multisecta, a leafy mustard, is widely grown in China as a vegetable (Fahey 2016). In May 2018, blackleg symptoms, grayish lesions with black pycnidia, were found on stems and leaves of B. juncea var. multisecta during disease surveys in Wuhan, Hubei Province. Disease incidence was approximately 82% of plants in the surveyed fields (~1 ha in total). To determine the causal agent of the disease, twelve diseased petioles were surface-sterilized and then cultured on potato dextrose agar (PDA) at 20˚C for 5 days. Six fungal isolates (50%) were obtained. All showed fluffy white aerial mycelia on the colony surface and produced a yellow pigment in PDA. In addition, pink conidial ooze formed on top of pycnidia after 20 days of cultivation on a V8 juice agar. Pycnidia were black-brown and globose with average size of 145 × 138 μm and ranged between 78 to 240 × 71 to 220 μm, n = 50. The conidia were cylindrical, hyaline, and 5.0 × 2.1 μm (4 to 7.1 × 1.4 to 2.9 μm, n=100). These results indicated that the fungus was Leptosphaeria biglobosa rather than L. maculans, as only the former produces yellow pigment (Williams and Fitt 1999). For molecular confirmation of identify, genomic DNAs were extracted and tested through polymerase chain reaction (PCR) assay using the species-specific primers LbigF, LmacF, and LmacR (Liu et al. 2006), of which DNA samples of L. maculans isolate UK-1 (kindly provided by Dr. Yongju Huang of University of Hertfordshire) and L. biglobosa ‘brassicae’ isolate B2003 (Cai et al. 2014) served as controls. Moreover, the sequences coding for actin, β-tubulin, and the internal transcribed spacer (ITS) region of ribosomal DNA (Vincenot et al. 2008) of isolates HYJ-1, HYJ-2 and HYJ-3 were also cloned and sequenced. All six isolates only produced a 444-bp DNA fragment, the same as isolate B2003, indicating they belonged to L. biglobosa ‘brassicae’, as L. maculans generates a 331-bp DNA fragment. In addition, sequences of ITS (GenBank accession no. MN814012, MN814013, MN814014), actin (MN814292, MN814293, MN814294), and β-tubulin (MN814295, MN814296, MN814297) of isolates HYJ-1, HYJ-2 and HYJ-3 were 100% identical to the ITS (KC880981), actin (AY748949), and β-tubulin (AY748995) of L. biglobosa ‘brassicae’ strains in GenBank, respectively. To determine their pathogenicity, needle-wounded cotyledons (14 days) of B. juncea var. multisecta ‘K618’ were inoculated with a conidial suspension (1 × 107 conidia/ml, 10 μl per site) of two isolates HYJ-1 and HYJ-3, twelve seedlings per isolate (24 cotyledons), while the control group was only treated with sterile water. All seedlings were incubated in a growth chamber (20°C, 100% relative humidity under 12 h of light/12 h of dark) for 10 days. Seedlings inoculated with conidia showed necrotic lesions, whereas control group remained asymptomatic. Two fungal isolates showing the same culture morphology to the original isolates were re-isolated from the necrotic lesions. Therefore, L. biglobosa ‘brassicae’ was confirmed to be the causal agent of blackleg on B. juncea var. multisecta in China. L. biglobosa ‘brassicae’ has been reported on many Brassica crops in China, such as B. napus (Fitt et al. 2006), B. oleracea (Zhou et al. 2019), B. juncea var. multiceps (Zhou et al. 2019), B. juncea var. tumida (Deng et al. 2020). To our knowledge this is the first report of L. biglobosa ‘brassicae’ causing blackleg on B. juncea var. multisecta in China, and its occurrence might be a new threat to leafy mustard production of China.

scholarly journals First Report of Curvularia aeria on Etlingera linguiformis from Nagaland, India

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1580-1580 ◽  
Author(s):  
C. Kithan ◽  
L. Daiho
Keyword(s):  
Leaf Surface ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Indian Agricultural Research Institute ◽  
Mountain Range ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Conidial Suspension ◽  
First Report ◽  
Initial Symptoms

Etlingera linguiformis (Roxb.) R.M.Sm. of Zingiberaceae family is an important indigenous medicinal and aromatic plant of Nagaland, India, that grows well in warm climates with loamy soil rich in humus (1). The plant rhizome has medicinal benefits in treating sore throats, stomachache, rheumatism, and respiratory complaints, while its essential oil is used in perfumery. A severe disease incidence of leaf blight was observed on the foliar portion of E. linguiformis at the Patkai mountain range of northeast India in September 2012. Initial symptoms of the disease are small brown water soaked flecks appearing on the upper leaf surface with diameter ranging from 0.5 to 3 cm, which later coalesced to form dark brown lesions with a well-defined border. Lesions often merged to form large necrotic areas, covering more than 90% of the leaf surface, which contributed to plant death. The disease significantly reduces the number of functional leaves. As disease progresses, stems and rhizomes were also affected, reducing quality and yield. The diseased leaf tissues were surface sterilized with 0.2% sodium hypochlorite for 2 min followed by rinsing in sterile distilled water and transferred into potato dextrose agar (PDA) medium. After 3 days, the growing tips of the mycelium were transferred to PDA slants and incubated at 25 ± 2°C until conidia formation. Fungal colonies on PDA were dark gray to dark brown, usually zonate; stromata regularly and abundantly formed in culture. Conidia were straight to curved, ellipsoidal, 3-septate, rarely 4-septate, middle cells broad and darker than other two end cells, middle septum not median, smooth, 18 to 32 × 8 to 16 μm (mean 25.15 × 12.10 μm). Conidiophores were terminal and lateral on hyphae and stromata, simple or branched, straight or flexuous, often geniculate, septate, pale brown to brown, smooth, and up to 800 μm thick (2,3). Pathogen identification was performed by the Indian Type Culture Collection, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi (ITCC Accession No. 7895.10). Further molecular identity of the pathogen was confirmed as Curvularia aeria by PCR amplification and sequencing of the internal transcribed spacer (ITS) regions of the ribosomal DNA by using primers ITS4 and ITS5 (4). The sequence was submitted to GenBank (Accession No. MTCC11875). BLAST analysis of the fungal sequence showed 100% nucleotide similarity with Cochliobolus lunatus and Curvularia aeria. Pathogenicity tests were performed by spraying with an aqueous conidial suspension (1 × 106 conidia /ml) on leaves of three healthy Etlingera plants. Three plants sprayed with sterile distilled water served as controls. The first foliar lesions developed on leaves 7 days after inoculation and after 10 to 12 days, 80% of the leaves were severely infected. Control plants remained healthy. The inoculated leaves developed similar blight symptoms to those observed on naturally infected leaves. C. aeria was re-isolated from the inoculated leaves, thus fulfilling Koch's postulates. The pathogenicity test was repeated twice. To our knowledge, this is the first report of the presence of C. aeria on E. linguiformis. References: (1) M. H. Arafat et al. Pharm. J. 16:33, 2013. (2) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (3) K. J. Martin and P. T. Rygiewicz. BMC Microbiol. 5:28, 2005. (4) C. V. Suberamanian. Proc. Indian Acad. Sci. 38:27, 1955.

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 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 First report of Alternaria alternata causing leaf blight on little millet (Panicum sumatrense) in India.

Plant Disease ◽  
2020 ◽  
Author(s):  
Boda Praveen ◽  
A. Nagaraja ◽  
M. K. Prasanna Kumar ◽  
Devanna Pramesh ◽  
K. B. Palanna ◽  
...  
Keyword(s):  
Crop Yields ◽  
Disease Incidence ◽  
Leaf Blight ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Pcr Assay ◽  
Causal Organism ◽  
First Report ◽  
Little Millet

Little millet (LM) is a minor cereal crop grown in the Indian sub-continent. During October 2018, dark brown, circular to oval necrotic spots surrounded by concentric rings were observed on the upper leaf surface of the LM (cv. VS-13) grown in the fields of the University of Agricultural Sciences, Bengaluru, India (13.0784oN, 77.5793oE). As the disease progressed, infected leaves became blighted. Disease incidence up to 53% was recorded in 3 fields of 0.4-hectare area each. Thirty symptomatic leaves were collected to isolate the associated causal organism. The margins of diseased tissue were cut into 5 × 5-mm pieces, surface-sterilized in 75% ethanol for 45 seconds followed by 1% sodium hypochlorite for 1 min, finally rinsed in sterile distilled water five times and placed on PDA. After 7 days of incubation at 25°C, greyish fungal colonies appeared on PDA. Single-spore isolations were performed to obtain ten isolates. Pure cultures of the fungus initially produced light gray aerial mycelia that later turned to dark grey. All isolates formed obclavate to pyriform conidia measured 22.66-48.97μm long and 6.55-13.79µm wide with 1-3 longitudinal and 2-7 transverse septa with a short beak (2.55-13.26µm) (n=50). Based on the conidial morphology, the fungus was identified as Alternaria sp. Further, the taxonomic identity of all ten isolates was confirmed as A. alternata using species-specific primers (AAF2/AAR3, Konstantinova et al. 2002) in a PCR assay. Later, one of the isolate UASB1 was selected, and its internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), major allergen Alt a 1 (Alt a 1), major endo-polygalacturonase (endoPG), OPA10-2, and KOG1058 genes were amplified in PCR (White et al. 1990; Berbee et al. 1999; Woudenberg et al. 2015), and the resultant products were sequenced and deposited in the NCBI GenBank (ITS, MN919390; gapdh, MT637185; Alt a 1, MT882339; endoPG, MT882340; OPA10-2, MT882341; KOG1058, MT882342). Blastn analysis of ITS, gapdh, Alt a 1, endoPG, OPA10-2, KOG1058 gene sequences showed 99.62% (with AF347031), 97.36% (with AY278808), 99.58% (with AY563301), 99.10% (with JQ811978), 99.05% (with KP124632) and 99.23% (with KP125233) respectively, identity with reference strain CBS916.96 of A. alternata, confirming UASB1 isolate to be A. alternata. For pathogenicity assay, conidial suspension of UASB1 isolate was spray inoculated to ten healthy LM (cv. VS-13) plants (45 days old) maintained under protected conditions. The spore suspension was sprayed until runoff on healthy leaves, and ten healthy plants sprayed with sterile water served as controls. Later, all inoculated and control plants were covered with transparent polyethylene bags and were maintained in a greenhouse at 28±2 ◦C and 90% RH. The pathogenicity test was repeated three times. After 8 days post-inoculation, inoculated plants showed leaf blight symptoms as observed in the field, whereas no disease symptoms were observed on non-inoculated plants. Re-isolations were performed from inoculated plants, and the re-isolated pathogen was confirmed as A. alternata based on morphological and PCR assay (Konstantinova et al. 2002). No pathogens were isolated from control plants. There is an increasing acreage of LM crop in India, and this first report indicates the need for further studies on leaf blight management and the disease impacts on crop yields.

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