First Report of Cercospora apii Leaf Spot on Capsicum chinense in Brazil

In Brazil, Capsicum chinense Jacq. is the predominant species of commercial hot peppers because of its popular citrus-like aroma and adaptability to different soils and climates (4). In June 2010, 30 samples of C. chinense with severe leaf spot were collected from a field in the city of Viçosa, state of Minas Gerais, Brazil. Symptoms were observed on leaves, calyxes, fruits, and stems on most of the plants found in the area. On leaves, symptoms included amphigenous lesions that were initially circular to ellipsoid, 1 to 5 mm in diameter, whitish to tan in the center, and surrounded by a dark brown or reddish purple border. Lesions coalesce and turned necrotic with age. A fungus isolated from the lesions matched well with the description of Cercospora apii Fresen. It formed erumpent stromata that were dark brown and spherical to irregular; fascicule conidiophores were clear brown or pale, straight or curved, unbranched, geniculate, 22.5 to 80 × 5 to 7.5 μm, 0 to 3 septate, subtruncate apex; and conidia were solitary, hyaline to subhyaline, filiform, base truncate, tip acute, straight to curved, 12.5 to 140 × 3.5 to 5 μm, and 0 to 11 septate (1,2). A sample was deposited in the herbarium of the Universidade Federal de Viçosa, Minas Gerais, Brazil (VIC 31415). Identity was confirmed by amplifying part of the calmodulin gene with species-specific primers CercoCal-apii and CercoCal-R (3) of fungal DNA from a single-spore culture. In amplification reaction, initial denaturation step was done at 94°C for 5 min, followed by 40 cycles of denaturation at 94°C (30 s), annealing at 56°C (30 s), and elongation at 72°C (30 s). Primers CercoCal-apii and CercoCal-R amplified a single DNA product of 176 bp, and coupled with the morphological characteristics, confirmed the identity of the fungus as Cercospora apii. To check pathogenicity, a 6-mm-diameter plug of the isolate was removed from the expanding edge of a 21-day-old culture grown on potato dextrose agar (PDA) and placed in contact with the adaxial face of the leaves of 8-week-old C. chinense grown in 2-liter plastic pots with soil substrate. Six plants, one per pot, were inoculated with the isolate and six plants were inoculated with the fungus-free PDA plug. Inoculated plants were maintained in a moist chamber for 24 h and then subsequently kept in a greenhouse at 26°C. Leaf spot was observed in all inoculated plants 15 days after inoculation and symptoms were similar to those expressed in the field. The fungus was reisolated from the inoculated plants and matched well with the description of Cercospora apii. All fungus-free PDA inoculated plants remained healthy. Cercospora apii comprises a complex of 281 morphologically indistinguishable species that can infect an extremely wide host range (2). To our knowledge, this pathogen has the potential to cause significant damage to the hot pepper industry of Brazil. References: (1) C. Chupp. A Monograph of the Fungus Cercospora. Cornell University Press, Ithaca, NY, 1954. (2) P. W. Crous and U. Braun. CBS Biodivers. Ser. 1:1, 2003. (3) M. Groenewald et al. Phytopathology 95:951, 2005. (4) S. D. Lannes et al. Sci. Hortic. 112:266, 2007.

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First Report of Cercospora Leaf Spot Caused by Cercospora apii (= C. molucellae) on Bells-of-Ireland (Molucella laevis) in Mexico

Plant Disease ◽

10.1094/pdis-93-2-0197a ◽

2009 ◽

Vol 93 (2) ◽

pp. 197-197 ◽

Cited By ~ 1

Author(s):

V. Ayala-Escobar ◽

U. Braun ◽

C. Nava-Diaz

Keyword(s):

Uv Light ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Cercospora Leaf Spot ◽

Single Spore ◽

First Report ◽

Cornell University ◽

Specific Fragment ◽

Species Specific

In late 2007, a new disease was found in commercial cutflower fields of bells-of-Ireland (Molucella laevis L.) in Texcoco, Mexico. Four plantings surveyed during this time had 100% incidence. A few spots on cutflowers make them unmarketable. Symptoms consisted of gray-green spots on leaves, calyxes, and stems, which turned brown with age. Spots were initially circular to oval, delimited by major leaf veins, and were visible on both adaxial and abaxial sides of the leaves. A Cercospora species was consistently associated with the spots. The fungus was isolated on V8 agar medium. Three single-spore cultures were obtained from isolation cultures. Cultures were incubated at 24°C under near-UV light for 7 days. Pathogenicity was confirmed by spraying a conidial suspension (1 × 104 condia/ml) on leaves of 16 potted M. laevis plants, incubating the plants in a dew chamber for 48 h, and maintaining them in a greenhouse (20 to 24°C). Identical symptoms to those observed in the field appeared on all inoculated plants after 2 weeks. No symptoms developed on control plants treated with autoclaved distilled water. The pathogenicity test was repeated twice with similar results. The fungus produced erumpent stromata, which were dark brown, spherical to irregular, 10 to 26 μm diameter, and giving rise to fascicles of five to nine divergent conidiophores, which were clear brown, paler near the subtruncate apex, straight to curved, not branched, rarely geniculate with two to four septa, and 57 × 3.4 μm. The conidia were formed singly, hyaline, acicular, base truncate, tip acute, straight to curved with 11 to 19 septa, and 172 × 3.5 μm. Fungal DNA from single-spore cultures was obtained with a commercial extraction kit (Qiagen, Hilden, Germany), amplified with ITS5 and ITS4 primers, and sequenced. The sequence, deposited at the National Center for Biotechnology Information Database (GenBank Accession No. EU564808), aligned almost perfectly (99% identity) to the bells-of-Ireland isolates from California (GenBank Accession Nos. AY156918 and AY156919) and New Zealand (Accession No. DQ233321). A 176-bp species-specific fragment was amplified with CercoCal-apii primers but not with CercoCal-beta or CercoCal-sp primers. These results, coupled with the morphological characteristics (1) and pathogenicity test, confirm the identity of the fungus as Cercospora apii sensu lato (including C. molucellae) (2,3,4). Although C. apii sensu lato has been reported on other hosts in Mexico (1,2), to our knowledge, this is the first report of this disease on M. laevis plants in this country. References: (1) C. Chupp. A Monograph of the Fungus Cercospora. Cornell University Press, Ithaca, NY, 1954. (2) P. W. Crous and U. Braun. CBS Biodiversity Series 1:1, 2003. (3) M. Groenewald et al. Phytopathology 95:951, 2005. (4) S. T Koike et al. Plant Dis. 87:203, 2003.

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First Report of Alternaria Leaf Spot of Banana Caused by Alternaria alternata in the United States

Plant Disease ◽

10.1094/pdis-01-13-0007-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1116-1116 ◽

Cited By ~ 3

Author(s):

V. Parkunan ◽

S. Li ◽

E. G. Fonsah ◽

P. Ji

Keyword(s):

United States ◽

Alternaria Alternata ◽

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Its Sequencing ◽

Single Spore ◽

First Report ◽

Alternaria Leaf Spot ◽

Leaf Spots

Research efforts were initiated in 2003 to identify and introduce banana (Musa spp.) cultivars suitable for production in Georgia (1). Selected cultivars have been evaluated since 2009 in Tifton Banana Garden, Tifton, GA, comprising of cold hardy, short cycle, and ornamental types. In spring and summer of 2012, 7 out of 13 cultivars (African Red, Blue Torres Island, Cacambou, Chinese Cavendish, Novaria, Raja Puri, and Veinte Cohol) showed tiny, oval (0.5 to 1.0 mm long and 0.3 to 0.9 mm wide), light to dark brown spots on the adaxial surface of the leaves. Spots were more concentrated along the midrib than the rest of the leaf and occurred on all except the newly emerged leaves. Leaf spots did not expand much in size, but the numbers approximately doubled during the season. Disease incidences on the seven cultivars ranged from 10 to 63% (10% on Blue Torres Island and 63% on Novaria), with an average of 35% when a total of 52 plants were evaluated. Six cultivars including Belle, Ice Cream, Dwarf Namwah, Kandarian, Praying Hands, and Saba did not show any spots. Tissue from infected leaves of the seven cultivars were surface sterilized with 0.5% NaOCl, plated onto potato dextrose agar (PDA) media and incubated at 25°C in the dark for 5 days. The plates were then incubated at room temperature (23 ± 2°C) under a 12-hour photoperiod for 3 days. Grayish black colonies developed from all the samples, which were further identified as Alternaria spp. based on the dark, brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (2). Conidia were 23 to 73 μm long and 15 to 35 μm wide, with a beak length of 5 to 10 μm, and had 3 to 6 transverse and 0 to 5 longitudinal septa. Single spore cultures of four isolates from four different cultivars were obtained and genomic DNA was extracted and the internal transcribed spacer (ITS1-5.8S-ITS2) regions of rDNA (562 bp) were amplified and sequenced with primers ITS1 and ITS4. MegaBLAST analysis of the four sequences showed that they were 100% identical to two Alternaria alternata isolates (GQ916545 and GQ169766). ITS sequence of a representative isolate VCT1FT1 from cv. Veinte Cohol was submitted to GenBank (JX985742). Pathogenicity assay was conducted using 1-month-old banana plants (cv. Veinte Cohol) grown in pots under greenhouse conditions (25 to 27°C). Three plants were spray inoculated with the isolate VCT1FT1 (100 ml suspension per plant containing 105 spores per ml) and incubated under 100% humidity for 2 days and then kept in the greenhouse. Three plants sprayed with water were used as a control. Leaf spots identical to those observed in the field were developed in a week on the inoculated plants but not on the non-inoculated control. The fungus was reisolated from the inoculated plants and the identity was confirmed by morphological characteristics and ITS sequencing. To our knowledge, this is the first report of Alternaria leaf spot caused by A. alternata on banana in the United States. Occurrence of the disease on some banana cultivars in Georgia provides useful information to potential producers, and the cultivars that were observed to be resistant to the disease may be more suitable for production. References: (1) E. G. Fonsah et al. J. Food Distrib. Res. 37:2, 2006. (2) E. G. Simmons. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands, 2007.

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

Plant Disease ◽

10.1094/pdis-01-21-0223-pdn ◽

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.

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STUDIES ON THE VARIABILITY OF THE PRODUCTIVITY COMPONENTS IN A COLLECTION OF HOT PEPPER LANDRACES (CAPSICUM ANUUM VAR. MICROCARPUM)

Current Trends in Natural Sciences ◽

10.47068/ctns.2021.v10i19.027 ◽

2021 ◽

Vol 10 (19) ◽

pp. 201-208

Author(s):

Emilian Madoşă ◽

Lavinia Sasu ◽

Sorin Ciulca ◽

Constantin Avădanei ◽

Adriana Ciulca ◽

...

Keyword(s):

Morphological Characteristics ◽

Fruit Production ◽

Fruit Weight ◽

Plant Production ◽

Average Weight ◽

Hot Pepper ◽

Breeding Programs ◽

Hot Peppers ◽

Biometric Measurements ◽

Western Romania

The aim of the research was to evaluate the variability value of the main characters that contribute to the achievement of plant production to a collection of hot pepper genotypes. The biological material was composed of 17 landraces of hot peppers collected from western Romania. The study was conducted for two years, with biometric measurements on the morphological characteristics of fruit production on the plant. Intra-population variability was assessed (mean, standard deviation of mean and coefficient of variability) and differences between populations for these characters. The results show that the variability within the collection is high. Within populations, fruit sizes (length, diameter) are uniform, but the number of fruits and their weight per plant show greater variability. Within the collection, variations in morphological characteristics are large, especially for fruit length, fruit weight, number and weight of fruit per plant. Among the landraces studied, some may be recommended for breeding programs, as parents or as material for the application of selection: for long fruits (Juliţa, Aldeşti I and Satchinez I), for short fruits (Satchinez III), but also the landraces Rieni III (17.07 g average weight of the fruit), Temerești II (89.82 fruits per plant), Aldești I (931.17 g fruits per plant).

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First Report of Leaf Spot Caused by Alternaria alternata on Yucca gloriosa in China

Plant Disease ◽

10.1094/pdis-04-21-0857-pdn ◽

2021 ◽

Author(s):

Qiang Zhang ◽

Yanru Zhang ◽

Hongli Shi ◽

Yunfeng Huo

Keyword(s):

Alternaria Alternata ◽

Leaf Spot ◽

Management Strategies ◽

Elongation Factor ◽

Morphological Characteristics ◽

Internal Transcribed Spacers ◽

Molecular Characteristics ◽

Single Spore ◽

Tissue Samples ◽

First Report

Yucca gloriosa L. is introduced to China as a garden plant because of its attractive tubular flowers (Ding et al. 2020). In 2020 and 2021, a foliar disease occurred on approximately 10% of the Y. gloriosa plants in the campus of Henan Institute of Science and Technology, Xinxiang (35°18′N, 113°54′E), Henan Province, China. At the early stages, symptoms appeared as small brown spots on the tip of the leaves. As the disease developed, the spots gradually expanded and turned into necrotic tissue with a clear brown border. The length of lesions ranged from 1 to 3 cm. Infected tissue samples were cut into small pieces, surface sterilized with 75% ethanol for 30 s followed by 0.5% NaClO for 2 min, rinsed thrice with sterile water and plated on potato dextrose agar (PDA). After incubation at 25℃ for 3 days, five fungal isolates were collected and purified using single spore culturing. Morphological observations were made on the 7-day-old cultures. Colonies on PDA were white at first and then turned to dark olive or black along with profuse sporulation. Conidia were borne on branched conidiophores, light brown to dark brown, ellipsoidal to obpyriform, and 20.5 to 43.6 ×7.5 to 15.4 μm in size, with 2-6 transverse septa and 0-3 longitudinal septa (n = 50). The morphological characteristics of the five isolates were consistent with the description for Alternaria alternata (Simmons 2007). One representative isolate (ZQ20) was selected for molecular identification. The internal transcribed spacers (ITS)-rDNA, translation elongation factor-1 alpha (TEF-1α), Alternaria major allergen (Alt a1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene regions were amplified with primer pairs ITS1/ITS4 (White et al. 1990), EFl-728F/ EFI-986R (Carbone and Kohn, 1999), Alt-for/Alt-rev (Hong et al. 2005), and gpd1/gpd2 (Berbee et al. 1999), respectively. Their sequences were submitted to GenBank (ITS, MW832377; TEF-1α, MW848791; Alt a1, MW848792; GAPDH, MW848793). BLAST searches showed ≥99% nucleotide identity to the sequences of A. alternata (ITS, 100% to KF465761; TEF-1α, 100% to MT133312; Alt a1, 100% to KY923227; and GAPDH, 99% to MK683863). Thus, the fungus was identified as A. alternata based on its morphological and molecular characteristics. To confirm its pathogenicity, 25 healthy leaves of five 2-year-old Y. gloriosa plants were used. Leaves were wounded with one sterile needle and inoculated with 5-mm-diameter fungal agar disks obtained from 5-day-old cultures. Sterile PDA disks of the same size were used as the controls. Treated plants were covered with a plastic bag at 12 to 25℃ for 48 h to ensure a high level of moisture. After 15 days, the inoculated plants developed the symptoms similar to those observed in naturally infected plants, whereas the control plants were symptomless. The fungus was reisolated from the symptomatic leaves with the same morphological and molecular characteristics as the original isolates, fulfilling the Koch's postulates. Leaf spot caused by A. alternata in the Yucca plants has been reported in India (Pandey 2019). To our knowledge, this is the first report of A. alternata causing leaf spot on Y. gloriosa in China. Identification of the cause of the disease is important to developing effective disease management strategies.

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First Report of Corynespora cassiicola Causing Leaf Spot of Cassava in China

Plant Disease ◽

10.1094/pdis-94-7-0916a ◽

2010 ◽

Vol 94 (7) ◽

pp. 916-916 ◽

Cited By ~ 1

Author(s):

X.-B. Liu ◽

T. Shi ◽

C.-P. Li ◽

J.-M. Cai ◽

G.-X. Huang

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Pathogenic Fungi ◽

Commonwealth Mycological Institute ◽

Corynespora Cassiicola ◽

Single Spore ◽

First Report ◽

Leaf Spots ◽

Main Vein

Cassava (Manihot esculenta) is an important economic crop in the tropical area of China. During a survey of diseases in July and September of 2009, leaf spots were observed on cassava plants at three separate plantations in Guangxi (Yunfu and Wuming) and Hainan (Baisha) provinces. Circular or irregular-shaped leaf spots were present on more than one-third of the plants. Spots were dark brown or had white papery centers delimited by dark brown rims and surrounded by a yellow halo. Usually, the main vein or small veinlets adjacent to the spots were dark. Some defoliation of plants was evident at the Wuming location. A fungus was isolated from symptomatic leaves from each of the three locations and designated CCCGX01, CCCGX02, and CCCHN01. Single-spore cultures of these isolates were incubated on potato dextrose agar (PDA) for 7 days with a 12-h light/dark cycle at a temperature of 28 ± 1°C. Conidiophores were straight to slightly curved, unbranched, and pale to light brown. Conidia were formed singly or in chains, obclavate to cylindrical, straight or curved, subhyaline-to-pale olivaceous brown, 19.6 to 150.3 μm long and 5.5 to 10.7 μm wide at the base, with 4 to 13 pseudosepta. Morphological characteristics of the specimen and their conidia were similar to the descriptions for Corynespora cassiicola (2). The isolate CCCGX01 was selected as a representative for molecular identification. Genomic DNA was extracted by the cetyltrimethylammoniumbromide protocol (3) from mycelia and used as a template for amplification of the internal transcribed spacer (ITS) region of rDNA with primer pair ITS1/ITS4. The sequence (GenBank Accession No. GU138988) exactly matched several sequences (e.g., GenBank Accession Nos. FJ852715, EF198117, and AY238606) of C. cassiicola (1). Young, healthy, and fully expanded green leaves of cassava cv. SC205 were surface sterilized. Ten leaves were inoculated with 10-μl drops of 104 ml suspension of conidia and five leaves were inoculated with the same volume of sterile water to serve as controls. After inoculation, leaves were placed in a dew and dark chamber for 36 h at 25°C and subsequently transferred to the light for 5 days. All inoculated leaves with isolates showed symptoms similar to those observed in natural conditions, whereas the controls remained symptom free. The morphological characteristics of reisolated conidia that formed on the diseased parts were identical with the nature isolates. To our knowledge, this is the first report of leaf spot caused by C. cassiicola on cassava in China. References: (1) L. J. Dixon et al. Phytopathology 99:1015, 2009. (2) M. B. Ellis et al. Corynespora cassiicola. No. 303 in: CMI Description of Pathogenic Fungi and Bacteria. Commonwealth Mycological Institute, Kew, UK 1971. (3) J. R. Xu et al. Genetics 143:175, 1996.

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First Report of Pestalotiopsis microspora Causing Leaf Spot of Hidcote (Hypericum patulum) in Japan

Plant Disease ◽

10.1094/pdis-94-8-1064b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1064-1064 ◽

Cited By ~ 3

Author(s):

M. Zhang ◽

H. Y. Wu ◽

T. Tsukiboshi ◽

I. Okabe

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Basal Cells ◽

Single Spore ◽

Management Options ◽

First Report ◽

Leaf Spots ◽

Plastic Bags ◽

Pestalotiopsis Microspora

Hidcote, Hypericum patulum Thunb. ex Murray, is a deciduous shrub that is cultivated as an ornamental in landscape gardens and courtyards in Japan. In early August 2008, severe leaf spotting was observed on plants growing in a courtyard in Nasushiobara, Tochigi, Japan. More than 30% of the leaves on five shrubs exhibited leaf spot symptoms. Small, round, pale brown lesions were initially observed. Later, they expanded to 5 to 12 mm in diameter, round to irregular-shaped with pale brown centers and dark brown margins. Under continuously wet or humid conditions, black acervuli developed on the leaf lesions. Conidia were straight or slightly curved, fusiform to clavate, and five-celled with constrictions at the septa. Conidia ranged from 17 to 21 × 5 to 8 μm with hyaline apical and basal cells. Fifteen percent of apical cells had two and the rest had three appendages (setulae) ranging from 10 to 21 μm long. The basal hyaline cell tapered into a 2 to 4 μm pedicel. The three median cells ranged from light or dark brown to olive green. These morphological characteristics matched those of Pestalotiopsis microspora (Speg.) G.C. Zhao & N. Li (1,2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. GU908473) from single-spore isolates, which revealed 100% homology with those of other P. microspora isolates (e.g., GenBank Accession Nos. FJ459950 and DQ456865). Koch's postulates were confirmed using leaves of three detached branches of a field-grown asymptomatic plant of H. patulum. Thirty leaves of each branch were inoculated by placing mycelial plugs obtained from the periphery of 7-day-old single-spore cultures on the leaf surface. Potato dextrose agar plugs without mycelium served as controls. Leaves on branches were covered with plastic bags for 24 h to maintain high relative humidity in a greenhouse (approximately 24 to 28°C). After 5 days, all inoculated leaves showed symptoms identical to those described above, whereas control leaves remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was P. microspora. To our knowledge, this is the first report of leaf spots on H. patulum caused by P. microspora in Japan. Management options may have to be developed and implemented to protect Hidcote plants in areas where leaf spot cannot be tolerated. References: (1) P. A. Saccardo. Sylloge Fungorum III:789, 1884. (2) G. C. Zhao and N. Li. J. Northeast For. Univ. 23(4):21, 1995.

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Occurrence of Leaf Spot Caused by Mycocentrospora acerina on Zhujieshen(Panax japonicus C. A. Mey.) in China

Plant Disease ◽

10.1094/pdis-08-21-1718-pdn ◽

2021 ◽

Author(s):

Jingmao You ◽

Tao Tang ◽

Fanfan Wang ◽

Jie Guo ◽

Yuanyuan Duan ◽

...

Keyword(s):

Leaf Spot ◽

Large Subunit ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Peat Moss ◽

Single Spore ◽

Agar Disc ◽

Ambient Lighting ◽

Initial Symptoms ◽

Panax Japonicus

Panax japonicus C. A. Mey., known as Japanese ginseng or “Zhujieshen” in China, is a perennial medicinal herb (family Araliaceae) native to China and is widely grown in many provinces including Hubei, Hunan, and Sichuan. In recent years, cultivation of Japanese ginseng has increased tremendously in China because of its high value. Its root is widely used in traditional Chinese medicine for the treatment of inflammation. In early May 2020, severe necrotic lesions on leaves with 40 to 50 % disease incidences were observed on 3-year-old Japanese ginseng plants in a cultivated field in Xuanen County (30°05′N, 109°83′E), Hubei Province, China. The total area affected by the disease was approximately 30 ha. Initial symptoms showed small, circular, brown, necrotic spots uniformly distributed on leaves. The center of the spots was light tan, surrounded by a dark brown ring and a chlorotic halo. As the disease progressed, multiple lesions merged into large disease spots with visible white fungal hyphae, causing leaf wilting. Ten small pieces (0.1 × 0.1 cm in size) of leaf tissue were removed from the lesion margins, surface-sterilized with 0.5 % sodium hypochlorite for 1 min and 75 % alcohol for 20 s, washed with sterile distilled water three times, dried, and placed on Petri plates with potato dextrose agar (PDA) medium containing 10 µg/ml of ampicillin and incubated at 20 °C for 5 days. Colonies with dense mycelia were initially white and gradually becoming black. The hyphae were septate, branched, and 3 to 7 µm in width. Conidiophores were flexuous, not branched, and produced a single spore. Spores (ranged from 95.4 to 255.5 × 6.2 to 13.5 μm) were elongate, multiseptate, with a long, strongly curved beak (ranged from 25.5 to 95.4 μm), The number of septae ranged from 4 to 13. Clamydospores with smooth or slightly rough wall were spherical to ovoid and averaged 8.5 to 25.4 × 7.2 to 16.5 μm. The six isolates were preliminarily identified as Mycocentrospora acerina (R. Hartig) Deightonbased on the morphological characteristics (Gilchrist et al. 2015). To confirm the identification, isolates ZJS1, ZJS3, and ZJS5 were chosen for DNA sequencing. The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1 and ITS4 primers (White et al. 1990) and sequenced. The identical sequences of the 491 bp amplicons were deposited in GenBank (accession no. ZJS1, MZ277314; ZJS3, OL333859; and ZJS5, OL333860). BLAST analysis of the sequences showed 100 % identity to M. acerina (MH856114). Moreover, the three isolates were further confirmed as M. acerina by amplifying the large subunit (LSU) of the ribosome gene (accession no. ZJS1, MZ277321; ZJS3, OL333861; and ZJS5, OL333862), as their identical sequences exhibited 99.83 % similarities with M. acerina (MH868490). Isolate ZJS1 was chosen to fulfill Koch’s postulates with 30 healthy 2-year-old P. japonicus grown in plastic pots filled with a sterilized mixture of peat moss and vermiculite (3:1). One leaf of each plant was inoculated with one 5-mm-diameter mycelium-agar disc and placed in a greenhouse at 20 ± 1 °C, with ambient lighting and relative humidity of 85 %. By 5 days after inoculation, all inoculated plants showed symptoms identical to those observed in the field, and no symptoms were observed on control plants. The fungus was reisolated from the inoculated plants and identified as M. acerina using the above method. The experiment was conducted thrice with similar results. To our knowledge, this is the first report of leaf spot caused by M. acerina on Japanese ginseng in China and the world. There is a need to develop effective management measures to reduce the occurrence of this disease.

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First Report of a Leaf Spot on Hazel Leaves Caused by Phyllosticta coryli in Liaoning Province of China

Plant Disease ◽

10.1094/pdis-02-13-0213-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1254-1254 ◽

Cited By ~ 10

Author(s):

J. Sun ◽

D.-M. Wang ◽

X.-Y. Huang ◽

Z.-H. Liu

Keyword(s):

Leaf Spot ◽

Control Strategies ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Its Region ◽

Liaoning Province ◽

Single Spore ◽

First Report ◽

Leaf Spots ◽

Microscopic Morphology

Hazel (Corylus heterophylla Fischl) is an important nut tree grown in China, especially in Liaoning Province, and is rich in nutritional and medicinal values. In August 2011, leaf spotting was observed on hybrid hazel (Dawei) leaves in Paotai Town, Wafangdian County of Liaoning Province. By August 2012, the disease had spread to Zhangdang Town, Fushun County. Symptoms initially appeared on both sides of leaves as pinpoint brown spots, which enlarged and developed into regular, dark brown lesions, 3 to 9 mm in diameter. The lesions were lighter in color in the center compared to the margin. To identify the pathogen, leaf pieces (3 to 5 mm) taken from the margins, including both symptomatic and healthy portions of leaf tissue, were surface-disinfected first in 75% ethanol for 5 s, next in 0.1% aqueous mercuric chloride for 50 s, and then rinsed with sterilized water three times. Leaf pieces were incubated on potato dextrose agar (PDA) at 25°C for 14 days in darkness. Single spore isolates were obtained from individual conidia. For studies of microscopic morphology, isolates were grown on synthetic nutrient agar (SNA) in slide cultures. Colonies grew up to 45 to 48 mm in diameter on PDA after 14 days. Pycnidia appeared on the colonies after 12 days. Conidiophores were short. Pycnidia were dark brown, subglobose, and 150 to 205 μm in diameter. Conidia were unicellular, colorless, ovoid to oval, and from 2.4 to 4.5 × 1.6 to 2.4 μm. On the basis of these morphological characteristics, the isolates were tentatively identified as Phyllosticta coryli Westend (2). The rDNA internal transcribed spacer (ITS) region was amplified using primers ITS1 and ITS4 and sequenced (GenBank Accession No. KC196068). The 490-bp amplicons had 100% identity to an undescribed Phyllosticta species isolated from Cornus macrophylla in Gansu, Tianshui, China (AB470897). On the basis of morphological characteristics and nucleotide homology, the isolate was tentatively identified as P. coryli. Koch's postulates were fulfilled in the growth chamber on hazelnut leaves inoculated with P. coryli conidial suspensions (107 conidia ml–1). Eight inoculated 1-year-old seedlings (Dawei) were incubated under moist conditions for 8 to 10 days at 25°C. All leaf spots that developed on inoculated leaves were similar in appearance to those observed on diseased hazel leaves in the field. P. coryli was recovered from lesions and its identity was confirmed by morphological characteristics. P. coryli was first reported as a pathogen of hazel leaves in Bull of Belgium (2). In China, P. coryli was first reported on Corylus heterophylla Fisch. in Jilin Province (1). To our knowledge, this is the first report of P. coryli causing leaf spot on hybrid hazel in Liaoning Province of China. The outbreak and spread of this disease may decrease the yield of hazelnut in northern regions of China. More studies are needed on control strategies, including the possible resistance of hazel cultivars to P. coryli. References: (1) Y. Li et al. J. Shenyang Agric. Univ. 25:153, 1994. (2) P. A. Saccardo. Sylloge Fungorum Vol. III, page 31, 1884.

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First Report of Leaf Spot Disease Caused by Glomerella magna on Lobelia chinensis in China

Plant Disease ◽

10.1094/pdis-03-13-0346-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1383-1383 ◽

Cited By ~ 4

Author(s):

Q. L. Li ◽

J. Y. Mo ◽

S. P. Huang ◽

T. X. Guo ◽

Z. B. Pan ◽

...

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Tween 20 ◽

Leaf Spot Disease ◽

Herbaceous Plant ◽

Single Spore ◽

First Report ◽

Small Water ◽

Perennial Herbaceous Plant

Lobelia chinensis is a perennial herbaceous plant in the family Campanulaceae that is native to China, where it grows well in moist to wet soils. It is commonly used as a Chinese herbal medicine. In May 2012, symptoms of leaf spot were observed on leaves of L. chinensis in Nanning, Guangxi Zhuang Autonomous Region, China. The leaf lesions began as small, water-soaked, pale greenish to grayish spots, which enlarged to gray to pale yellowish spots, 4 to 6 mm in diameter. At later stages, numerous acervuli appeared on the lesions. Acervuli were mostly epiphyllous, and 40 to 196 μm in diameter. On potato dextrose agar (PDA), a fungus was consistently recovered from symptomatic leaf samples, with a 93% isolation rate from 60 leaf pieces that were surface sterilized in 75% ethanol for 30 s and then in 0.1% mercuric chloride for 45 s. Three single-spore isolates were used to evaluate cultural and morphological characteristics of the pathogen. Setae were two to three septate, dark brown at the base, acicular, and up to 90 μm long. Conidia were long oblong-elliptical, guttulate, hyaline, and 11 to 20 × 4.1 to 6.3 μm (mean 15.2 × 5.1 μm). These morphological characteristics of the fungus were consistent with the description of Colletotrichum magna (teleomorph Glomerella magna Jenkins & Winstead) (1). The rDNA internal transcribed spacer (ITS) region of one isolate, LC-1, was sequenced (GenBank Accession No. KC815123), and it showed 100% identity to G. magna, GenBank HM163187.1, an isolate from Brazil cultured from papaya (2). Although KC815123 was identified as G. magna, it shows 99% identity to GenBank sequences from isolates of C. magna, and more research is needed to elucidate the relationships between these taxa, especially with consideration to host specificity. Pathogenicity tests were performed with each of the three isolates by spraying conidial suspensions (1 × 106 conidia/ml) containing 0.1% Tween 20 onto the surfaces of leaves of 30-day-old and 6- to 8-cm-high plants. For each isolate, 30 leaves from five replicate plants were treated. Control plants were treated with sterilized water containing 0.1% Tween 20. All plants were incubated for 36 h at 25°C and 90% relative humidity in an artificial climate chamber, and then moved into a greenhouse. Seven days after inoculation, gray spots typical of field symptoms were observed on all inoculated leaves, but no symptoms were seen on water-treated control plants. Koch's postulates were fulfilled by reisolation of G. magna from diseased leaves. To our knowledge, this is the first report of G. magna infecting L. chinensis worldwide. References: (1) M. Z. Du et al. Mycologia 97:641, 2005. (2) R. J. Nascimento et al. Plant Dis. 94:1506, 2010.

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