First Report of Anthracnose Caused by Colletotrichum theobromicola on Barbados Cherry (Malpighia emarginata) in Brazil

Barbados cherry, also called acerola, is a fruit originated from tropical America that is well-known for its high content of vitamin C and nutritional value. Anthracnose is one of the most common diseases on Barbados cherry. In Brazil, this disease is associated with Colletotrichum gloeosporioides sensu lato (2). In 2012, necrotic and sunken spots were observed on Barbados cherry fruit (cv. Rubra) in Sao Paulo State, Brazil, from which a Colletotrichum species was isolated on potato dextrose agar (PDA). The isolate was grown on PDA at 25°C and 12-h photoperiod under fluorescent light. The colony was gray on the upper surface and the reverse part was dark gray. Conidia (n = 50) were cylindrical to subcylindrical, hyaline, and 12 to 15 (avg. 12.7) × 3.8 to 5.9 (avg. 4.3) μm. Conidia length/width ratio was 2 to 3.6. Pathogenicity was confirmed on Barbados cherry fruit. Inoculation was carried out by depositing 40-μl droplets of a conidial suspension (1 × 105 conidia ml−1) on fruit wounded with a sterilized needle and on non-wounded fruit. Fruit were incubated in a moist chamber at 25°C. First symptoms appeared 3 and 5 days after inoculation on wounded and non-wounded fruit, respectively. No symptoms were observed on control fruit inoculated with water. Six isolates recovered from inoculated fruit showed the same morphological characteristics of the previous isolate. The DNA of the fungus was extracted by a CTAB protocol (1) and the sequences of ITS, GAPDH, ACT, CHS-1, TUB, and CAL genes (4) were generated. Sequences were used in BLAST searches in GenBank and were 100% similar to C. theobromicola, except for GAPDH. The ITS (KC566724) and CAL (KC566437) sequences matched strain ICMP 17099 (JX010285 and JX009588, respectively) with 100% identity. The BTUB (KC566148), GAPDH (KC566578), ACT (KC566870), and CHS-1(KC566292) sequences matched with the strains ICMP 18649 (JX010447, 100% identity), ICMP 17099 (JX009957, 99% identity, 1 pb), ICMP 18567 (JX009457, 100% identity), and ICMP 18613 (JX009771, 100% identity), respectively. The sequences were also compared with authentic culture of C. gloeosporioides (IMI 356878) and the identities were: ITS 99% (JX010148), CAL 91% (JX009729), BTUB 90% (JX010445), GAPDH 83% (GU174561), ACT 93% (JX009494), and CHS-1 98% (JX009747). Based on the multi-gene sequencing, the isolate was identified as C. theobromicola. C. theobromicola was described in 2010 (3) and it is considered as a widely distributed species occurring on different hosts in tropical and subtropical regions (4). This report shows the necessity of the identification of Colletotrichum species from tropical fruits to elucidate the etiology of anthracnose diseases of which C. gloeosporioides sensu lato is considered to be the causal agent. To our knowledge, this is the first report of C. theobromicola on Barbados cherry. References: (1) M. G. Murray and W. F. Thompson. Nucleic Acids Res. 8:4321, 1980. (2) R. Ritzinger et al. Acerola em Foco 13:1, 2007. (3) E. I. Rojas et al. Mycologia 102:1318, 2010. (4) B. S. Weir et al. Stud. Mycol. 73:115, 2012.

Download Full-text

First Report of Colletotrichum boninense Causing Anthracnose on Pepper in Brazil

Plant Disease ◽

10.1094/pdis-93-1-0106a ◽

2009 ◽

Vol 93 (1) ◽

pp. 106-106 ◽

Cited By ~ 16

Author(s):

H. J. Tozze ◽

N. M. Massola ◽

M. P. S. Câmara ◽

R. Gioria ◽

O. Suzuki ◽

...

Keyword(s):

Morphological Characteristics ◽

Hypodermic Needle ◽

Molecular Characteristics ◽

Width Ratio ◽

Conidial Suspension ◽

Rio Grande Do Sul ◽

First Report ◽

Potted Plants ◽

Length Width ◽

Orange Color

Colletotrichum boninense was isolated from pepper (Capsicum annuum) fruits (cv. Amanda) with preharvest anthracnose symptoms collected in the Brazilian states of Rio Grande do Sul and São Paulo in July of 2005. In the field, the disease affected mature fruits and leaves with an incidence near 25%. Typical symptoms in fruits were circular, sunken lesions with orange spore masses in a dark center. Three single conidia isolates were obtained from infected fruits. When grown on potato dextrose agar at 25°C with a 12-h photoperiod, these isolates produced white colonies with a cream-to-orange color in the opposite side, but no sclerotia. Conidia were cylindrical, had obtuse ends and a hilum-like low protuberance at the base, and measured 13.5 to 15.5 × 4.6 to 5.1 μm. Conidial length/width ratio was 2.8 to 3.0. These morphological characteristics are consistent with the description of C. boninense (1). To confirm pathogen identity, the internal transcribed spacer rRNA region was sequenced (GenBank Accession Nos. FJ010199, FJ010200, and FJ010201) and compared with the same region of C. boninense (GenBank Accession No. DQ286160.1). Similarity between these sequences was 98 to 99%. The pathogenicity of the three isolates was determined on pepper fruits cv. Amanda. Attached as well as detached fruits from potted plants were inoculated. Inoculation was performed by depositing 40-μl droplets of a suspension (105 conidia per ml) on the surfaces of nonwounded (detached n = 5; attached n = 5) and wounded (detached n = 5; attached n = 5) fruits with a sterilized hypodermic needle. Incubation took place in a moist chamber for 12 days at 25°C with a 12-h photoperiod. Inoculation of control fruits was similar in procedure and number to that of test fruits, except sterile distilled water was used instead of the conidial suspension. Symptoms, observed in wounded and nonwounded test fruits 3 to 5 days after inoculation, were characterized by necrotic, sunken zones containing acervuli, black setae, and orange spore masses. Control fruits presented no symptoms. Pathogens reisolated from infected fruits showed the same morphological and molecular characteristics of the isolates previously inoculated. To our knowledge, this is the first report of C. boninense infecting pepper in Brazil. Reference: (1) J. Moriwaki et al. Mycoscience 44:47, 2003.

Download Full-text

First Report of Colletotrichum tropicale Causing Anthracnose on Common Fig in Taiwan

Plant Disease ◽

10.1094/pdis-06-21-1329-pdn ◽

2021 ◽

Author(s):

Chung-hang Duan ◽

Guan-ying Chen

Keyword(s):

Manganese Superoxide Dismutase ◽

Morphological Characteristics ◽

Width Ratio ◽

Conidial Suspension ◽

Gene Sequences ◽

First Report ◽

Fungal Isolates ◽

Common Fig ◽

Colletotrichum Tropicale ◽

Central Taiwan

Ficus carica L. known as common fig is one of the most profitable fruit crops in Taiwan. Their fruit are harvested for high-priced market. Common fig can be eaten fresh or dried and processed to make different food products. In September 2015, an anthracnose-like disease was widely observed on common fig fruit planted in an orchard in Lukang township (24°04'36" N, 120°27'15" E) in Changhua County, central Taiwan. Symptoms were sunken, water-soaked lesions covered with salmon-colored spore masses and were observed on all stages of fruit, especially when fruit was ripe. Four fungal isolates were collected from four diseased fruit of different plants in the same orchard. Conidia were spread on 2% water agar, and a single conidium was separated by a handmade glass needle. Fungal isolates were grown on potato dextrose agar (PDA) at 24 to 28°C with diffused light. All four strains produced white, aerial, and cottony mycelia covered with abundant salmon-colored conidial masses on PDA. The conidia were hyaline, single celled, round cylindrical on both ends, thin walled, and the contents guttulate. The sizes of conidia were 15.4 (18.5 to 13.1) × 4.73 (5.8 to 3.6) μm [average (max. to min.); length/width ratio = 3.25, n = 40]. DNA was isolated from the representative isolate FC1 and used for amplification of partial sequences of the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), β-tubulin 2 (TUB2), manganese-superoxide dismutase (SOD2), calmodulin (CAL), chitin synthase 1 (CHS-1) (Weir et al. 2012) and the intergenic region of apn2 and MAT1-2-1 gene (ApMat) genes (Sharma et al. 2013). A BLAST search against the NCBI database revealed that FC1 gene sequences [GenBank accession nos. MT192648 (ITS), MT155819 (GAPDH), MT199873 (ACT), MT199874 (TUB2), MT815916 (SOD2), MT815917 (CAL), MW684717 (CHS-1) and MT221652 (ApMat)] displayed 99.1, 98.2, 99.3, 99.6, 99.5, 100.0, 92.8 and 100.0% nucleotide identity to the respective gene sequences of Colletotrichum tropicale CBS 124949 (ICMP18653) (JX010264, JX010007, JX009489, JX010407, JX010329, JX009719, JX009870 and KC790728). Multilocus phylogenetic analysis performed with reference sequences showed that the isolate FC1 clustered with C. tropicale in accordance with BLAST results. A conidial suspension (1 × 106 conidia/mL) prepared from FC1 isolate was inoculated by spraying onto detached, ripe, healthy, non-wounded and surface-disinfected common fig fruit (cv. China, n = 4). Fruit sprayed with sterile water were used as control. Fruit were kept in a moist chamber (greater than 90% relative humidity, 24 to 28°C) for 24 h and then maintained in the lab for additional 5 days. The inoculated fruit developed lesions similar to the disease symptoms in the orchard. No symptom was observed on fruit treated with water. C. tropicale was re-isolated from symptomatic fruits and had similar morphological characteristics to FC1 isolate, thus fulfilling Koch’s postulates. The experiment was repeated once showing similar results. The FC1 isolate of C. tropicale with the identification number BCRC FU31436 has been deposited at Taiwan Bioresource Collection and Research Center. This fungus had previously been found on lotus and mango in Taiwan (Chen and Kirschner 2018; Wu et al. 2020), while the pathogenicity among the isolates from different origins is not yet known. To our knowledge, this is the first report of C. tropicale causing anthracnose on common fig fruit in Taiwan.

Download Full-text

First Report of Fusarium Wilt in Blueberry (Vaccinium corymbosum) Caused by Fusarium oxysporum in China

Plant Disease ◽

10.1094/pdis-02-14-0167-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1158-1158 ◽

Cited By ~ 1

Author(s):

Y. H. Liu ◽

T. Lin ◽

C. S. Ye ◽

C. Q. Zhang

Keyword(s):

Fusarium Oxysporum ◽

Infected Plant ◽

Morphological Characteristics ◽

Vaccinium Corymbosum ◽

Morphological Characterization ◽

Internal Transcribed Spacers ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report

Blueberry (Vaccinium corymbosum) production is developing quickly in China with about 20,000 ha presently cultivated. In 2010 in Lin'an, Zhejiang Province, plants developed an apparently new disease of blueberry (cv. Duke) with symptoms consisting of wilting of foliage, stunting of plants, and reduced fruit yields. Internal vascular and cortical tissues of plant crowns showed a brown to orange discoloration. Approximately 3% of the plants in the commercial plantings were affected and eventually died after 50 to 60 days. Infected plant samples (stems and roots) collected from different fields were surface sterilized with 1.5% sodium hypochlorite for 2 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on acidified PDA (APDA) for morphological characterization (1,2). Colonies were light with purple mycelia, and beige or orange reverse colony colors developed after 7 days incubation at 25°C. Colonies producing abundant microconidia and macroconidia. Microconidia were hyaline and oval-ellipsoid to cylindrical (3.9 to 9.6 × 1.1 to 3.4 μm). Macroconidia were 3 to 5 septate and fusoid-subulate with a pedicellate base (28.6 to 37.5 × 3.3 to 4.2 μm). Morphology and development of macroconidia and microconida were consistent with a description of Fusarium oxysporum Schltdl (1,2). The ribosomal internal transcribed spacers ITS1 and ITS2 of eight isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of F. oxysporum. To confirm pathogenicity, 20 blueberry plants (cv. Duke) were inoculated by dipping the roots into a conidial suspension (107 conidia per ml) for 30 min. The inoculated plants were transplanted into pots containing sterilized peat and maintained at 25°C and 100% relative humidity in a growth chamber with a daily 12-h photoperiod of fluorescent light. The pathogenicity test was conducted twice. Within 40 days, all inoculated plants developed wilt symptoms similar to that observed in the field. No symptoms were observed on plants dipped into distilled water. The fungus was successfully re-isolated from crowns and roots cultured on APDA, exhibiting morphological characteristics identical to F. oxysporum (1,2), confirming Koch's postulates. To our knowledge, this is the first report of blueberry wilt caused by Fusarium. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, Wallingford, UK, 2008. (2) W. C. Snyder and H. N. Hansen. Am. J. Bot. 27:64, 1940.

Download Full-text

First Report of Colletotrichum cliviicola Causing Leaf Spot on Tobacco (Nicotiana tabacum) in Hunan Province of China

Plant Disease ◽

10.1094/pdis-02-21-0409-pdn ◽

2021 ◽

Author(s):

Ya Rong Wang ◽

Zhao Hu ◽

Jie Zhong ◽

Yi Chen ◽

Jun Zi Zhu

Keyword(s):

Nicotiana Tabacum ◽

Leaf Spot ◽

Morphological Characteristics ◽

Disease Diagnosis ◽

Hunan Province ◽

Leaf Spot Disease ◽

Post Inoculation ◽

Conidial Suspension ◽

First Report ◽

Colletotrichum Species

Tobacco (Nicotiana tabacum L.) is an annual, leafy, herb of the genus Nicotiana in the family Solanaceae. It is an important commercial crop in China. In 2020, a leaf spot disease was observed on tobacco leaves in commercial fields in the Hunan Province of China. Symptoms appeared as water-soaked, yellow-green spots, then turned dark brown, and coalesced into larger necrotic lesions, often leading to leaf wilt. Approximately 20% of the plants in a 50-ha area were infected, exhibiting symptomatic spots on 60% of these leaves. Symptomatic leaf samples were collected and cut into small pieces, sterilized with 70% ethanol for 10 s, 0.1% HgCl2 for 40s, rinsed with sterile distilled water for three times, plated on potato dextrose agar (PDA) and incubated at 26°C in the dark. Isolates with similar morphology were developed from ten samples. Fungal isolates produced densely, white to dark green, aerial mycelium. Conidia were straight, hyaline, aseptate, cylindrical, contained oil globules, and 15 to 25 µm × 3.0 to 4.0 µm (n=50). Appressoria were dark brown, irregularly shaped, 5.5 to 10.0 μm × 4.5 to 6.5 μm (n=50). These morphological characteristics were typical of Colletotrichum cliviicola (Yang et al. 2009). For molecular identification, the internal transcribed spacer (ITS) region of rDNA, actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and chitin synthase (CHS-1) genes of a representative isolate CS16-2 were amplified and sequenced using the primer pairs as described previously (Weir et al. 2012). These sequences were deposited in GenBank (GenBank Accession Nos. MW649137 for ITS, MW656181 for ACT, MW656182 for GAPDH and MW656183 for CHS-1). BLAST analysis showed that they had 99.46% to 100% identity to the corresponding sequences of C. cliviicola strains. A concatenated phylogenetic tree was generated, using the ACT, GAPDH and CHS-1 sequences of the isolate CS16-2 and other closely matching Colletotrichum species obtained from the GenBank. We found that the CS16-2 was grouped with the C. cliviicola clade with 97% bootstrap support, including the C. cliviicola strain AH1B6 (Wang et al. 2016). Pathogenicity was tested spraying 2-month-old potted tobacco plants until runoff with a conidial suspension (105 spores/ml). Leaves were mock inoculated with sterilized water. The pathogenicity tests were performed twice, with three replicate plants each. Plants were kept in humid chambers at 26°C with a 12-h photoperiod. Five days post-inoculation, the inoculated plants developed symptoms of consisting of the yellow-brown necrotic lesion resembling the symptoms that were observed in fields, while the control plants remained symptomless. C. cliviicola was re-isolated and identified by morphological and molecular methods as described above. Currently, C. cliviicola has been reported to be the causal agent of anthracnose in some plants, such as soybean (Zhou et al. 2017) and Zamioculcas zamiifolia (Barbieri et al. 2017). However, to our knowledge, this is the first report of C. cliviicola causing leaf spot on tobacco in China and even in the word. Given that the may greatly affect the yield and quality of tobacco production, growers should be prepared to manage this new disease. This work might provide further insight for disease diagnosis on tobacco as some other Colletotrichum species, such as C. fructicola (Wang et al. 2016) and C. karsti (Zhao et al. 2020), have also been responsible for anthracnose.

Download Full-text

First Report of Phytophthora cambivora Causing Leaf and Stem Blight and Root Rot on Taiwan Cherry (Prunus campanulata) in Taiwan

Plant Disease ◽

10.1094/pdis-01-12-0025-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1065-1065

Author(s):

J.-H. Huang ◽

P.-J. Ann ◽

Y.-H. Chiu ◽

J.-N. Tsai

Keyword(s):

Severe Disease ◽

Morphological Characteristics ◽

Its Region ◽

Internal Transcribed Spacers ◽

Nuclear Ribosomal Dna ◽

Linear Growth Rate ◽

Fluorescent Light ◽

Width Ratio ◽

First Report ◽

Zoospore Suspension

Taiwan cherry or Formosan cherry (Prunus campanulata Maxim.) is a beautiful ornamental tree that is native to Taiwan. In spring 2005, a severe disease was observed on 1- to 3-year-old seedlings of Taiwan cherry in a garden in Tungshih, Taichung, Taiwan. Infected plants showed symptoms of greenish water-soaked spots on leaves that became dark brown, 2 to 3 cm in diameter. Infected leaves withered and fell to the ground in 3 to 5 days and young shoots showed symptoms of withering and drooping. Infected roots showed symptoms of necrosis. Severely infected plants eventually died. A Phytophthora sp. was isolated consistently from diseased samples of Taiwan cherry and associated soil. Six isolates of Phytophthora, of the A1 mating type (1), were isolated from single zoospores. Two of these isolates, Tari 25141 (deposited as BCRC34932 in Bioresource Collection and Research Center, Shinchu, Taiwan) and Tari 25144 (BCRC34933), were used for pathogenicity tests on 1-year-old seedlings of Taiwan cherry to fulfill Koch's postulates. Inoculation was done by placing a cotton swab containing zoospore suspension on leaves or stem, or by soaking seedlings in the zoospore suspension. Inoculated seedlings were kept in a greenhouse at 20 to 25°C for 30 days and examined for appearance of symptoms. Results showed that both isolates were pathogenic on seedlings of Taiwan cherry, causing symptoms similar to those observed on naturally infected seedlings. The temperature range for growth of the six isolates of Phytophthora was 8 to 32°C with optimum temperature at 24°C. The linear growth rate was 72 mm per day on V8A culture (5% V8 vegetable juice, 0.02% CaCO3, and 2% Bacto agar) at 24°C. The colonies on potato dextrose agar produced sparse aerial mycelia with conspicuous radiate patterns. Sporangia were sparse on V8A agar blocks, but abundant when the agar blocks were placed in water under continuous white fluorescent light (average 2,000 lux) for 2 days. Sporangiophores branched sympodially. Sporangia were pear shaped, nonpapillate and nondeciduous, 50 to 75 (62) × 30 to 48 (40) μm, with a length/width ratio of 1.2 to 2.2 (1.6). New internal nested proliferate sporangia were formed inside the empty sac of old matured sporangia after releasing zoospores. No chlamydospores were formed on V8A. Hyphal swellings with distinctive irregular catenulation were produced on V8A and in water. The pathogen was stimulated to form its own oospores by the A2 tester using the method described by Ko (1). Oogonia were 28 to 50 (40) μm in diameter with smooth or irregularly protuberant walls. Oospores were mostly aplerotic and 18 to 42 (31) μm in diameter. Antheridia were amphigynous, mostly two-celled, and 10 to 42 (29) × 12 to 24 (19) μm. The sequence of the internal transcribed spacers (ITS) region of nuclear ribosomal DNA of isolate Tari 25141 (GenBank Accession No. GU111589) was 831 bp and had 99% sequence identity with a number of Phytophthora cambivora isolates such as GenBank Accession Nos. HM004220 (2), AY787030, and EF486692. Based on the morphological characteristics of sporangia and sexual structures and the molecular analysis of ITS sequences, the pathogen from Taiwan cherry was identified as P. cambivora (Petri) Buis. To our knowledge, this is the first report of P. cambivora on native Taiwan cherry in Taiwan and, so far, no other natural hosts have been reported. References: (1) W. H. Ko. J. Gen. Microbiol. 116:459, 1980. (2) P. W. Reeser et al. Mycologia 103:225, 2011.

Download Full-text

First Report of Colletotrichum cereale Causing Anthracnose Foliar Blight of Creeping Bentgrass in Mississippi and Alabama

Plant Disease ◽

10.1094/pdis-92-10-1475a ◽

2008 ◽

Vol 92 (10) ◽

pp. 1475-1475 ◽

Cited By ~ 4

Author(s):

J. R. Young ◽

M. Tomaso-Peterson ◽

J. A. Crouch

Keyword(s):

Morphological Characteristics ◽

Creeping Bentgrass ◽

Grass Species ◽

Fluorescent Light ◽

Conidial Suspension ◽

First Report ◽

Foliar Blight ◽

Colletotrichum Cereale ◽

Uninoculated Control ◽

Foliar Tissue

Colletotrichum cereale Manns, formerly C. graminicola (Ces.) G.W. Wils., is the causal agent of anthracnose foliar blight (AFB) of creeping bentgrass (Agrostis stolonifera L.) and other grass species (1). AFB is most prevalent on creeping bentgrass during summer heat stress (2). Symptoms of AFB progress from older to younger leaves with leaf tips becoming chlorotic and eventually developing complete leaf necrosis. Symptoms in turf stands appear as yellow-to-bronze, irregularly shaped patches often associated with a loss of turf density (2). When C. cereale is actively infecting the foliar tissue, appressoria can be observed microscopically in the leaf sheaths of creeping bentgrass. C. cereale colonizes the foliar tissue, producing abundant acervuli, where conidia and setae develop. Creeping bentgrass samples exhibiting symptoms of AFB were collected from West Point, MS and Birmingham, AL in July 2006. Symptomatic plants with signs of C. cereale were surface disinfested and plated onto one-quarter-strength potato dextrose agar (PDA). Monoconidial C. cereale isolates were grown on full-strength PDA for 21 days at 25°C under fluorescent lights. Single-celled conidia were mostly falcate, ranged from 13.1 to 25.6 μm long × 3.6 to 6.3 μm wide, and averaged 22.2 × 4.7 μm. Hyphal appressoria were irregularly shaped and heavily lobed, ranging from 5.6 to 16.1 μm long × 4 to 10.6 μm wide, and averaged 12.1 × 7.9 μm. In culture, setae were acicular, five to seven septate, thick walled, ranged from 74 to 213.5 μm long, and averaged 151.3 μm. The morphological characteristics of 44 AFB isolates were similar to those of C. cereale reported by Crouch et al. (1). Nucleotide sequences were generated for the internal transcribed spacer rDNA for isolates OO7-T42, OW15-H32, and 04-111 (GenBank Accession Nos. EU859957, EU859958, and EU859959). Maximum likelihood-based phylogenetic analyses of these sequences with authentic isolates of Colletotrichum species from grass hosts (2) indicated that all three isolates were C. cereale. ‘Penn A-1’ creeping bentgrass seedlings (10.16-cm pots) were inoculated with the C. cereale isolates OO7-T42, OW15-H32, or 04-111 by spraying a conidial suspension (1.5 × 105 conidia/ml) on plants until water droplets were evident within the canopy. An uninoculated control sprayed with distilled water only was used for comparison. Three replicates per C. cereale isolate were included simultaneously when performing Koch's postulates. The inoculated creeping bentgrass seedlings were placed in covered plastic boxes to maintain humidity and incubated under 12 h of fluorescent light with day/night temperatures at 35/28°C. After 4 days, the covers were removed and creeping bentgrass was maintained an additional 14 days until symptoms and signs were observed on the foliage. C. cereale was reisolated from inoculated creeping bentgrass exhibiting symptoms of AFB for all three isolates used. No acervuli, setae, or conidial masses were observed on uninoculated control plants. To our knowledge, this is the first report of C. cereale causing AFB on creeping bentgrass in Mississippi and Alabama. References: (1) J. A. Crouch et al. Phytopathology 96:46, 2006. (2) R. W. Smiley et al. Compendium of Turfgrass Diseases. The American Phytopathological Society, St. Paul, MN, 2005.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe heraclei on Parsley in Korea

Plant Disease ◽

10.1094/pdis-09-13-0972-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 847-847

Author(s):

S. E. Cho ◽

M. J. Park ◽

J. H. Park ◽

J. Y. Kim ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Its Region ◽

Petroselinum Crispum ◽

Width Ratio ◽

Anethum Graveolens ◽

First Report ◽

Organic Farm ◽

Length Width ◽

A Minor

Parsley, Petroselinum crispum (Mill.) Nyman, is a minor but important leaf crop in Korea. In June 2010, parsley plants (cv. Paramount) showing typical symptoms of powdery mildew were found with approximately 90% incidence (percentage of plants showing symptoms) in polyethylene-film-covered greenhouses in an organic farm in Icheon County of Korea. Symptoms first appeared as thin white colonies, which subsequently showed abundant growth on the leaves with chlorosis and crinkling. Most diseased plantings were unmarketable and shriveled without being harvested. The damage due to powdery mildew infections on parsley has reappeared in Icheon County and Gangneung City with confirmation of the causal agent made again in 2011 and 2012. Voucher specimens were deposited in the Korea University Herbarium (KUS). Appressoria on the mycelium were multilobed or moderately lobed. Conidiophores were cylindrical, 75 to 125 × 8 to 10 μm, straight in foot-cells, and produced conidia singly, followed by 2 to 3 cells. Conidia were oblong-elliptical to oblong, 32 to 55 × 14 to 20 μm with a length/width ratio of 1.7 to 2.9, lacked fibrosin bodies, and produced germ tubes on the perihilar position, with angular/rectangular wrinkling of the outer walls. First-formed conidia were apically conical, basally subtruncate to rounded, and generally smaller than the secondary conidia. Chasmothecia were not found. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements and morphological characteristics were consistent with those of E. heraclei DC. (1). To confirm the identity of the causal fungus, the complete ITS region of rDNA from isolate KUS-F25037 was amplified with primers ITS5 and P3 (3) and sequenced directly. The resulting 606-bp sequence was deposited in GenBank (Accession No. KF680162). A GenBank BLAST search of this sequence revealed 100% identity with that of E. heraclei on Anethum graveolens from Korea (JN603995) and >99% similarity with those of E. heraclei on Daucus carota from Mexico (GU252368), Pimpinella affinis from Iran (AB104513), Anthriscus cerefolium from Korea (KF111807), and many other parsley family (Apiaceae) plants. Pathogenicity was verified through inoculation by gently pressing diseased leaves onto leaves of five healthy potted parsley plants. Five non-inoculated plants served as negative controls. Inoculated plants developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. Parsley powdery mildew caused by E. heraclei has been known in Europe, North America, Brazil, and Japan (2,4). To our knowledge, this is the first report of powdery mildew infections by E. heraclei on parsley in Korea. Since cultivation of parsley was only recently started on a commercial scale in Korea, powdery mildew infections pose a serious threat to safe production of this herb, especially those grown in organic farming where chemical options are limited. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved September 17, 2013. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) Y. Tsuzaki and K. Sogou. Proc. Assoc. Plant Prot. Shikoku 24:47, 1989.

Download Full-text

First Report of Colletotrichum aenigma Causing Anthracnose of Grape in Korea

Plant Disease ◽

10.1094/pdis-11-20-2458-pdn ◽

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.

Download Full-text

First Report of Golovinomyces cichoracearum Causing Powdery Mildew on Zinnia elegans in China

Plant Disease ◽

10.1094/pdis-11-20-2333-pdn ◽

2020 ◽

Author(s):

Mo Zhu ◽

Jie Ji ◽

Xiao Duan ◽

YongFang Li

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

Zinnia Elegans ◽

Width Ratio ◽

Post Inoculation ◽

First Report ◽

Golovinomyces Cichoracearum ◽

Length Width

Zinnia elegans, common zinnia, is an annual plant with highly ornamental values. It is widely planted in many nurseries, city parks, universities and home gardens in China. From August to October 2020, powdery mildew-like signs and symptoms were observed on leaves of Z. elegans growing on the campus of Henan Normal University, Henan Province, China. White powdery colonies in circular- or irregularly shaped-lesions were abundant on both surfaces of leaves and covered up to 95 % of the leaf area. Any infected leaves were chlorotic, deformed or senescence. More than 70 % of the monitored Z. elegans plants showed these signs and symptoms. Conidiophores (n = 20) were 100 to 200 × 9 to 13 μm and composed of foot cells, followed by straight cells and conidia. Mycelial appressoria were single and nipple-shaped. The oval-shaped conidia (n = 30) were 22 to 36 × 12 to 18 μm, with a length/width ratio of 1.4 to 2.7, and produced germ tubes from the polar ends of the spore. No chasmothecia were found. Based on these morphological characteristics, the pathogen was initially identified morphologically as Golovinomyces cichoracearum (Braun and Cook 2012). Structures of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method previously described by Zhu et al. (2019). The internal transcribed spacer (ITS) region of rDNA was amplified by PCR using the primers ITS1/ITS4 (White et al. 1990) and the amplicon was sequenced by Invitrogen (Shanghai, China). The sequence for the fungus was deposited into GenBank under Accession No. MW029904 and was 99.83 % identical (595/596 bp) to G. cichoracearum on Symphyotrichum novi-belgii (HM769725)(Mørk et al. 2011). To perform pathogenicity analysis, leaf surfaces of five healthy plants were fixed in a settling tower and then inoculated by blowing fungal conidia from mildew-infested leaves using pressurized air. Five non-inoculated plants served as a control. The inoculated and non-inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Eleven- to twelve-days post-inoculation, powdery mildew signs were conspicuous on inoculated plants, while control plants remained healthy. Similar results were obtained by conducting two repeated pathogenicity assays. Thus, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as G. cichoracearum. This pathogen has been reported on Z. elegans in India, Israel, Jordan, Korea, Nepal, Sri Lanka, Switzerland, and Turkey (Farr and Rossman 2020). To our best knowledge, this is the first report of G. cichoracearum on Z. elegans in China. The sudden outbreak of powdery mildew caused by G. cichoracearum on Z. elegans may adversely impact the plant health and ornamental value in China. Therefore, the confirmation of G. cichoracearum infecting Z. elegans expands the understanding of this pathogen and provides the fundamental knowledge for future powdery mildew control.

Download Full-text

First Report of Powdery Mildew Caused by Podosphaera xanthii on Hibiscus mutabilis in Korea

Plant Disease ◽

10.1094/pdis-01-13-0065-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1118-1118

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. K. Lee ◽

C. H. Shin ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Natural Habitat ◽

Morphological Characteristics ◽

Its Region ◽

Width Ratio ◽

Korean Isolate ◽

First Report ◽

Public Garden ◽

Young Leaves ◽

Length Width

Hibiscus mutabilis L., known as cotton rose, is a deciduous shrub native to China. Horticultural varieties of the species are widely planted throughout the world (4). In September 2012, typical powdery mildew symptoms on the cotton rose were observed in a public garden of Jeju City, Korea. Powdery mildew colonies were circular to irregular white patches on both sides of the leaves and also on young stems and sepals. As the disease progressed, white mycelial growth covered the entire shoot portion, causing leaf distortion. In the middle of November, numerous chasmothecia were formed on the lesions. Voucher specimens (n = 4) were deposited in the Korea University Herbarium (KUS). Hyphal appressoria were only swollen part of hyphae or occasionally nipple-shaped. Conidiophores were 140 to 275 × 10 to 11.5 μm and produced 2 to 8 immature conidia in chains with a crenate outline. Foot-cells of conidiophores were straight, 30 to 65 μm long, and cylindric. Conidia were hyaline, ellipsoid-ovoid, and measured 27 to 42 × 17.5 to 21 μm with a length/width ratio of 1.5 to 2.4, and had distinct fibrosin bodies. Chasmothecia were amphigenous, cauligenous, 85 to 110 μm in diameter, and contained one ascus each. Peridium cells of chasmothecia were irregularly polygonal, large, and 15 to 38 μm wide. Appendages were mycelioid, 1- to 6-septate, brown at the base, and becoming paler. Asci were sessile, oval to broadly fusiform, with terminal oculus of 15 to 20 μm wide. Ascospores numbered eight per ascus were ellipsoidal, 19 to 25 × 14 to 16 μm. The morphological characteristics were consistent with previous records of P. xanthii (Castagne) U. Braun & Shishkoff (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from isolate KUS-F27134 was amplified with the primers ITS5 and P3 and sequenced (3). The resulting sequence of 477 bp was deposited in GenBank (Accession No. KC460208). The Korean isolate showed >99% similarity with dozens of sequences of P. xanthii ex cucurbitaceous hosts (e.g., JQ912061, JQ409565, HM070403, etc.) as well as Podosphaera sp. ex H. mutabilis from Japan (AB040308). Pathogenicity was confirmed through inoculation tests by gently pressing diseased leaves onto young leaves of three asymptomatic, potted 2-year-old seedlings. Three non-inoculated seedlings were used as controls. Plants were maintained in a greenhouse at 24 to 30°C. Inoculated leaves developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was morphologically identical to that observed on the original diseased leaves, fulfilling Koch's postulates. Powdery mildew infections of H. mutabilis associated with P. xanthii (including P. fuliginea in broad sense) have been known in China, Japan, and Taiwan (1,2). To our knowledge, this is the first report of powdery mildew caused by P. xanthii on H. mutabilis in Korea. Since Jeju, the southmost island of Korea, is the only habitat of cotton rose in Korea and is the northmost natural habitat in Asia, powdery mildew is a new threat to the health of wild populations of cotton rose. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved January 18, 2013. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) D. A. Wise. J. Hered. 64:285, 1973.

Download Full-text