scholarly journals Leaf Spot and Stem Blight Caused by Botrytis cinerea on Poinsettia in Argentina

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1359-1359
Author(s):  
H. E. Palmucci ◽  
P. E. Grijalba
Keyword(s):  
Botrytis Cinerea ◽  
Leaf Spot ◽  
Buenos Aires ◽  
Pathogenic Fungi ◽  
Pathogenicity Test ◽  
Euphorbia Pulcherrima ◽  
Conidial Suspension ◽  
Stem Blight ◽  
Potted Plants ◽  
Leaf Spots

Poinsettia (Euphorbia pulcherrima Will. ex. Klotzsch) is a worldwide potted or landscape ornamental plant that belongs to the Euphorbiaceae family. During 2003 and 2004, several symptoms were observed on poinsettia potted plants in nurseries and crops near Buenos Aires. Symptoms included irregular, brown, water-soaked spots on adult plants and leaf spots that extended causing stem blight in seedlings. Small pieces of diseased tissues were surface disinfected for 2 min in 2% sodium hypochlorite, plated on 2% potato dextrose agar (PDA), and incubated at 22°C for 48 h. Dense, whitish mycelia developed on PDA and then turned gray when asexual structures were formed. The fungus conidia were ellipsoid, hyaline, nonseptate, and were formed on botryose heads. The pathogenicity test was carried out on 10 plants using a conidial suspension (2 × 106 spores per ml) that was sprayed on leaves with and without injuries. All plants were incubated in a moist chamber at 22 ± 2°C for 48 h and then maintained in a greenhouse. After 3 days, symptoms similar to the original were observed on the inoculated plants. Control plants sprayed with distilled water remained symptomless. Koch's postulates were confirmed by reisolating the same fungus from diseased plants. In accordance with conidial and cultural characteristics, the pathogen was identified as Botrytis cinerea Pers: Fr. (1). To our knowledge, this is the first report of B. cinerea causing leaf spot and stem rot on poinsettia in Buenos Aires, Argentina. Reference: (1) M. V. Ellis and J. M. Waller. No. 431 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1974.

scholarly journals Brown leaf spot of Cycas debaoensis Caused by Colletotrichum siamense in Sichuan, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shan Han ◽  
Jimin Ma ◽  
Yanyue Li ◽  
Shujiang Li ◽  
yinggao Liu ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Negative Control ◽  
Wild Plants ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Potted Plants ◽  
Brown Leaf Spot ◽  
Brown Leaf

Cycas debaoensis Y. C. Zhong et C. J. Chen is an endemic species in China that is listed among China’s national key preserved wild plants (Class I) (Xie et al. 2005). It is mainly distributed in south China (Guangxi, Guizhou, and other regions). In April 2017, a new leaf disease of C. debaoensis was found in Chengdu (30°35′32″ N; 104°05′11″E) in China with an incidence over 40%. Symptoms on C. debaoensis initially appeared as brown necrotic lesions on the margin or in the center of leaves. The lesions then enlarged gradually and developed into brown spots, necrotic lesions with dark brown margins. Many small and black dots were observed on necrotic lesions. Eventually, the diseased leaves withered and died. Ten samples were collected and surface-sterilized by 3% NaClO and 75% ehanol respectively for 60s and 90s, rinsed with autoclaved distilled water and then blot-dried with autoclaved paper towels. Five isolates from diseased leaves with similar morphology were isolated from single spores. Morphological characteristics were recorded from pure cultures grown on potato dextrose agar (PDA) incubated at 25°C for 3-9 days. Initially, the colonies grown on PDA were white, then, became pale gray with concentric zones and greenish black beneath. Conidia were single-celled, smooth-walled, straight, colorless, cylindrical with both ends bluntly rounded,13.0-16.5 × 4.7-5.8 μm in size (n = 100 spores). For molecular identification, the genomic DNA of the isolates was extracted using a DNeasyTM Plant Mini Kit (Qiagen). The internal transcribed spacer (ITS) (ITS1/ITS4 White et al., 1990), β-tubulin (TUB2) (BT2A/BT2B (O’Donnell et al., 1997)), actin (ACT) (ACT512F/ACT (Carbone & Kohn, 1999)), calmodulin (CAL) (CL1C/CL2C (Weir et al., 2012)), mating type protein and chitin synthase (CHS-1) (CHS-1) (CHS-9 79F/CHS-345R (Carbone & Kohn, 1999)) were amplified. BLAST results indicated that the ITS, TUB2, ACT, CAL, CHS-1 sequences (GenBank MN305712, MN605072, MT478663, MT465591 and MT478664) showed 99-100% identity with C. siamense sequences at NCBI (GenBank JF710564, MK341542, MK855094, MH351155 and MK471373). The Phylogenetic tree inferred from the combined dataesets (TEF, TUB and ACT) show that the isolate belongs to C. siamense clade with a credibility value of 99%. Two-year-old potted plants of C. debaoensis (10 plants) were used for pathogenicity test. On each plant, 5 leaves were sprayed with a conidial suspension (1 × 106 conidia/ml) on both sides of the leaves. Autoclaved distilled water was used as negative control (10 plants). Plants were kept in the greenhouse at 25 °C under 16h/8h photoperiod and 70-75% relative humidity (RH). The symptoms observed on the inoculated plants were similar to those observed in the field, while the controls remained asymptomatic. C. siamense was re-isolated from all diseased inoculated plants, and the culture and fungus characteristics were the same as the original isolate. The morphological characteristics and molecular analyses of the isolate matched the description of C. siamense (Prihastuti et al., 2009). C. siamense was previously reported infecting Citrus reticulata (Cheng et al. 2013), but this is the first report of brown leaf spot on C. debaoensis caused by C. siamense in China. This finding provides important basis for further research on the control of the disease.

scholarly journals First Report of Corynespora Leaf Spot on Ailanthus altissima Caused by Corynespora cassiicola in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 586-586 ◽  
Author(s):  
J. H. Park ◽  
M. J. Park ◽  
S. H. Lee ◽  
H. D. Shin
Keyword(s):  
Leaf Spot ◽  
Central China ◽  
Ailanthus Altissima ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Corynespora Cassiicola ◽  
Leaf Spots ◽  
Adult Trees

Ailanthus altissima (Mill.) Swingle, known as tree-of-heaven, is a deciduous tree belonging to the family Simaroubaceae, which is native to both northeast and central China and Taiwan. The trees often have the ability to replace indigenous plants and disrupt native ecosystems (3). In August 2010, a leaf spot disease was observed on young trees in Yangpyeong, Korea. Field observation in 2010 and 2011 showed that infections are common on 1- or 2-year-old trees. Adult trees were rarely infected. Symptoms usually started at the margin of leaves and expanded into irregular, dark brown leaf spots, eventually causing significant premature defoliation. Representative samples were deposited in the herbarium of Korea University (KUS-F25174 and -F25304). Conidiophores of fungi observed microscopically on the leaf spots were erect, brown to dark brown, single or occasionally in clusters, 80 to 550 × 5 to 8 μm, and mostly arose on the abaxial surface of symptomatic leaves. Conidia were borne singly or in short chains of two to four, ranging from cylindrical to broadest at the base and tapering apically, straight to slightly curved, pale olivaceous brown, 3 to 18 pseudoseptate, 70 to 450 × 8 to 22 μm, each with a conspicuous thickened hilum. On potato dextrose agar, single-spore cultures of five isolates were identified as Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei on the basis of morphological and cultural characteristics (1,4). A monoconidial isolate was preserved at the Korean Agricultural Culture Collection (Accession No. KACC45510). Genomic DNA was extracted with the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced with an ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 548 bp was deposited in GenBank (Accession No. JN974462). The sequence showed >99% similarity (1-bp substitution) with a sequence of C. cassiicola from Ipomoea batatas (GenBank Accession No. FJ852716). To conduct a pathogenicity test, a conidial suspension (~2 × 104 conidia/ml) was prepared by harvesting conidia from 2-week-old cultures of KACC45510 and the suspension sprayed onto the leaves of three healthy seedlings. Three noninoculated seedlings served as control plants. Inoculated and noninoculated plants were kept in humid chambers for 48 h in a glasshouse. After 5 days, typical leaf spot symptoms started to develop on the leaves of all three inoculated plants. C. cassiicola was reisolated from the lesions, confirming Koch's postulates. No symptoms were observed on control plants. C. cassiicola is cosmopolitan with a very wide host range (2). To our knowledge, C. cassiicola has not been reported on A. altissima anywhere in the world. According to field observations in Korea, Corynespora leaf spot was most severe in August and September, especially following a prolonged period of moist weather. C. cassiicola may be a potential biocontrol agent for this highly invasive tree species. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute: Kew, Surrey, England, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA, Retrieved from http://nt.ars-grin.gov/fungaldatabes/ , October 28, 2011. (3) L. B. Knapp and C. D. Canham. J. Torrey Bot. Soc. 127:307, 2000. (4) J. H. Kwon et al. Plant Pathol. J. 17:180, 2001.

scholarly journals First Report of Leaf Spot on Industrial Hemp (Cannabis sativa L.) Caused by Alternaria alternata in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Lili Tang ◽  
Xixia Song ◽  
Liguo Zhang ◽  
Jing Wang ◽  
Shuquan Zhang
Keyword(s):  
Leaf Spot ◽  
Cannabis Sativa ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Sterile Water ◽  
First Report ◽  
Leaf Spots ◽  
Industrial Hemp

Industrial hemp is an economically important plant with traditional uses for textiles, paper, building materials, food and medicine (Li 1974; Russo et al. 2008; Zlas et al. 1993). In August 2020, an estimated 80% of the industrial hemp plants with leaf spots were observed in greenhouse in Minzhu town, Harbin City, Heilongjiang Province, China (45.8554°N, 126.8167°E), resulting in yield losses of 20%. Leaf symptoms began as small spots on the upper surface of leaves and gradually developed into brown spots with light yellow halos. These irregular spots expanded gradually and eventually covered the entire leaf; the center of the spots was easily perforated. To identify the pathogen, 20 diseased leaves were collected, and small sections of (3 to 5 mm) were taken from the margins of lesions of infected leaves. The pieces were sterilized with 75% alcohol for 30 s, a 0.1% mercuric chloride solution for 1 min, and then rinsed three times with sterile water. Samples were then cultured on potato dextrose agar at 28℃ in darkness for 4 days. A single-spore culture was obtained by monosporic isolation. Conidiophores were simple or branched, straight or flexuous, brown, and measured 22 to 61 μm long × 4 to 5 μm wide (n = 50). Conidia were solitary or in chains, brown or dark brown, obclavate, obpyriform or ellipsoid. Conidia ranged from 23 to 55 μm long × 10 to 15 μm wide (n = 50) with one to eight transverse and several longitudinal septa. For molecular identification (Jayawardena et al. 2019), genomic DNA of pathogenic isolate (MZ1287) was extracted by a cetyltrimethylammonium bromide protocol. Four gene regions including the rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosplate dehydrogenase (GAPDH), translation elongation factor 1-alpha (TEF1) and RNA polymerase II beta subunit (RPB2) were amplified with primers ITS1/ITS4, GDF1/GDR1, EF1-728F/EF1-986R and RPB2-5F/RPB2-7cR, respectively (White et al. 1990). Resulting sequences were deposited in GenBank with accession numbers of MW272539.1, MW303956.1, MW415414.1 and MW415413.1, respectively. A BLASTn analysis showed 100% homology with A. alternata (GenBank accession nos. MN615420.1, MH926018.1, MN615423.1 and KP124770.1), respectively. A neighbor-joining phylogenetic tree was constructed by combining all sequenced loci in MEGA7. The isolate MZ1287 clustered in the A. alternata clade with 100% bootstrap support. Thus, based on morphological (Simmons 2007) and molecular characteristics, the pathogen was identified as A. alternata. To test pathogenicity, leaves of ten healthy, 2-month-old potted industrial hemp plants were sprayed using a conidial suspension (1×106 spores/ml). Control plants were sprayed with sterile water. All plants were incubated in a greenhouse at 25℃ for a 16 h light and 8 h dark period at 90% relative humidity. The experiment was repeated three times. After two weeks, leaf spots of industrial hemp developed on the inoculated leaves while the control plants remained asymptomatic. The A. alternata pathogen was re-isolated from the diseased leaves on inoculated plants, fulfilling Koch's postulates. Based on morphology, sequencing, and pathogenicity test, the pathogen was identified as A. alternata. To our knowledge, this is the first report of A. alternata causing leaf spot disease of industrial hemp (Cannabis sativa L.) in China and is worthy of our attention for the harm it may cause to industrial hemp production.

scholarly journals First Report of Corynespora Leaf Spot of Eucalyptus in China

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 419-419 ◽  
Author(s):  
C. K. Phan ◽  
J. G. Wei ◽  
F. Liu ◽  
B. S. Chen ◽  
J. T. Luo ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Southern China ◽  
Tap Water ◽  
Pathogenic Fungi ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Eucalyptus is widely planted in the tropics and subtropics, and it has become an important cash crop in Southern China because of its fast-growing nature. In the Guangxi Province of southern China, Eucalyptus is produced on approximately 2 million ha, and two dominant asexual clones, Guanglin No. 9 (E. grandis × E. urophylla) and DH3229 (E. urophylla × E. grandis), are grown. Diseases are an increasing threat to Eucalyptus production in Guangxi since vast areas are monocultured with this plant. In June 2013, a leaf spot disease was observed in eight out of 14 regions in the province on a total of approximately 0.08 million ha of Eucalyptus. Initially, the lesions appeared as water-soaked dots on leaves, which then became circular or irregular shaped with central gray-brown necrotic lesions and dark red-brown margins. The size of leaf spots ranged between 1 and 3 mm in diameter. The main vein or small veins adjacent to the spots were dark. The lesions expanded rapidly during rainy days, producing reproductive structures. In severe cases, the spots coalesced and formed large irregular necrotic areas followed by defoliation. The causal fungus was isolated from diseased leaves. Briefly, the affected leaves were washed with running tap water, sterilized with 75% ethanol (30 s) and 0.1% mercuric dichloride (3 min), and then rinsed three times with sterilized water. Small segments (0.5 to 0.6 cm2) were cut from the leading edge of the lesions and plated on PDA. The plates were incubated at 25°C for 7 to 10 days. When mycelial growth and spores were observed, a single-spore culture was placed on PDA and grown in the dark at 25°C for 10 days. A pathogenicity test was done by spraying a conidial suspension (5 × 105 conidia ml–1) of isolated fungus onto 30 3-month-old leaves of Guanglin No. 9 seedlings. The plants were covered with plain plastic sheets for 7 days to keep the humidity high. Lesions similar to those observed in the forests were observed on the inoculated leaves 7 to 10 days after incubation. The same fungus was re-isolated. Leaves of control plants (sprayed with sterilized water) were disease free. Conidiophores of the fungus were straight to slightly curved, erect, unbranched, septate, and pale to light brown. Conidia were formed in chains or singly with 4 to 15 pseudosepta, which were oblong oval to cylindrical, subhyaline to pale olivaceous brown, straight to curved, 14.5 to 92.3 μm long, and 3.5 to 7.1 μm wide. The fungus was morphologically identified as Corynespora cassiicola (1). DNA of the isolate was extracted, and the internal transcribed spacer (ITS) region (which included ITS 1, 5.8S rDNA gene of rDNA, and ITS 2) was amplified with primers ITS5 and ITS4. 529 base pair (bp) of PCR product was obtained and sequenced. The sequence was compared by BLAST search to the GenBank database and showed 99% similarity to C. cassiicola (Accession No. JX087447). Our sequence was deposited into GenBank (KF669890). The biological characters of the fungus were tested. Its minimum and maximum growth temperatures on PDA were 7 and 37°C with an optimum range of 25 to 30°C. At 25°C in 100% humidity, 90% of conidia germinated after 20 h. The optimum pH for germination was 5 to 8, and the lethal temperature of conidia was 55°C. C. cassiicola has been reported causing leaf blight on Eucalyptus in India and Brazil (2,3) and causing leaf spot on Akebia trifoliate in Guangxi (4). This is the first report of this disease on Eucalyptus in China. References: (1) M. B. Ellis and P. Holliday. CMI Descriptions of Pathogenic Fungi and Bacteria, No. 303. Commonwealth Mycological Institute, Kew, Surrey, UK, 1971. (2) B. P. Reis, et al. New Dis. Rep. 29:7, 2014. (3) K. I. Wilson and L. R. Devi. Ind. Phytopathol. 19:393, 1966. (4) Y. F. Ye et al. Plant Dis. 97:1659, 2013.

scholarly journals Severe Outbreak of Leaf Spot and Blight Caused by Botrytis cinerea on Majesty Palm in Southern Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 815-815
Author(s):  
G. Polizzi
Keyword(s):  
Botrytis Cinerea ◽  
Leaf Spot ◽  
Southern Italy ◽  
Gray Mold ◽  
Limiting Factor ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Leaf Spots ◽  
Important Region ◽  
Leaf Tissues

Sicily is the most important region of Italy for ornamental palm cultivation. Majesty palm (Ravenea rivularis Jum. & H. Perrier) is one of the most stately palms for cultivation in the tropics and subtropics, and has been recently cultivated in containers for indoor and outdoor use in eastern Sicily. R. rivularis, which grows on river banks, is native to Madagascar, and appears to behave as a rheophyte in the seedling stage. This palm is not frost tolerant and will grow in full sun but tends to grow best in partly shaded areas or under greenhouses conditions. Between December and March in 1999, 2000, and 2001, a severe leaf spot and blight was observed on young (6-month- to 3-year-old) plants of majesty palm growing in plastic-covered houses and in open fields in nurseries in Sicily. Affected plants had brown necrotic spots and gray mold on the necrotic leaf tissues. No symptoms were detected in mature (4- to 5-year-old) plants grown in the same nurseries. To isolate the casual agent of the disease, 160 small pieces of tissue cut from leaf spots collected in four nurseries were surface sterilized (20 s in HgCl2 at 1 g/liter), washed with sterile water, and plated on potato dextrose agar (PDA). In addition, conidia and conidiophores were scraped from the leaf surface, suspended in sterile water, and streaked on the agar surface. After 2 days, single hyphal tips were transferred to PDA. Botrytis cinerea Pers.:Fr. was consistently isolated from affected leaf tissues. Colonies of B. cinerea on PDA were at first colorless and became gray to brown with the development of conidia, which ranged from 5.5 to 10 × 7 to 12 μm (average 7.5 × 9). Sclerotia were black, irregular in size and shape, and from 1.4 to 4.5 × 1.5 to 2.7 mm. Inoculating 8-month-old seedlings of R. rivularis tested pathogenicity of six isolates obtained from different nurseries. Wounded (with a needle) and nonwounded leaves of 10 plants (9 wounds per plant) were sprayed with 20 ml of a conidial suspension (105 conidia/ml) of each isolate. An equal number of noninoculated plants were used as controls. All plants where incubated in a greenhouse at ambient temperature (21 ± 2°C) and 72 h of continuous leaf wetness. Five days after inoculation, leaf spots appeared on most of the wounded (approximately 80%) and the nonwounded (about 10%) leaves. No symptoms were observed on control plants. Koch's postulates were satisfied by reisolation of the fungus on PDA. On the basis of 3 years of observations in eastern Sicily, majesty palms were more readily infected by B. cinerea after rainfall, and freezing temperatures injured young plants. Leaf blight caused by B. cinerea was previously reported in Liguria (northern Italy) on Phoenix canariensis (1). The fungus does not appear to be a major disease problem in cultivated ornamental palms other than R. rivularis in Sicily or southern Italy. However, B. cinerea could be a limiting factor in the cultivation of majesty palm in eastern Sicily, and protective fungicides, especially in winter, are necessary for limiting losses. To my knowledge, this is the first report of B. cinerea leaf spot and blight on R. rivularis. Reference: (1) A. Garibaldi et al. Malattie delle piante ornamentali. Calderini Edagricole, Bologna, 2000.

scholarly journals First report of leaf spot disease caused by Corynespora cassiicola on American sweetgum (Liquidambar styraciflua L.) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yun-fei Mao ◽  
Xiang-rong Zheng ◽  
Fengmao Chen
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Liquidambar Styraciflua ◽  
Bootstrap Support ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Corynespora Cassiicola ◽  
First Report ◽  
Leaf Spots

American sweetgum (Liquidambar styraciflua L.) is a forest plant native to North America, which has been introduced into other countries due to its ornamental and medicinal values. In June 2019, symptoms of leaf spots on sweetgum were observed in a field (5 ha) located in Xuzhou, Jiangsu Province, China. On this field, approximately 45% of 1,000 trees showed the same symptoms. Symptoms were observed showing irregular or circular dark brown necrotic lesions approximately 5 to 15 mm in diameter with a yellowish margin on the leaves. To isolate the pathogen, diseased leaf sections (4×4mm) were excised from the margin of the lesion, surface-sterilized with 0.1% NaOCl for 90 s, rinsed 4 times in sterile distilled water, air dried and then transferred on potato dextrose agar (PDA) medium at 25°C in the dark. Pure cultures were obtained by monospore isolation after subculture. Ten purified isolates, named FXI to FXR, were transferred to fresh PDA and incubated as above to allow for morphological and molecular identification. After 7 days, the aerial mycelium was abundant, fluffy and exhibited white to greyish-green coloration. The conidia were dark brown or olive, solitary or produced in chains, obclavate, with 1 to 15 pseudosepta, and measured 45 to 200µm  10 to 18µm. Based on morphological features, these 10 isolates were identified as Corynespora cassiicola (Ellis et al. 1971). Genomic DNA of each isolate was extracted from mycelia using the cetyltrimethylammonium bromide (CTAB) method. The EF-1α gene and ITS region were amplified and sequenced with the primer pairs rDNA ITS primers (ITS4/ITS5) (White et al. 1990) and EF1-728F/EF-986R (Carbone et al.1999) respectively. The sequences were deposited in GenBank. BLAST analysis revealed that the ITS sequence had 99.66% similarity to C. cassiicola MH255527 and that the EF-1α sequence had 100% similarity to C. cassiicola KX429668A. maximum likelihood phylogenetic analysis based on EF-1α and ITS sequences using MEGA 7 revealed that ten isolates were placed in the same clade as C. cassiicola (Isolate: XQ3-1; accession numbers: MH572687 and MH569606, respectively) at 98% bootstrap support. Based on the morphological characteristics and phylogenetic analyses, all isolates were identified as C. cassiicola. For the pathogenicity test, a 10 µl conidial suspension (1×105 spores/ml) of each isolate was dripped onto healthy leaves of 2-year-old sweetgum potted seedlings respectively. Leaves inoculated with sterile water served as controls. Three plants (3 leaves per plant) were conducted for each treatment. The experiment was repeat twice. All seedlings were enclosed in plastic transparent incubators to maintain high relative humidity (90% to 100%) and incubated in a greenhouse at 25°C with a 12-h photoperiod. After 10 days, leaves inoculated with conidial suspension of each isolate showed symptoms of leaf spots, similar to those observed in the field. Control plants were remained healthy. In order to reisolate the pathogen, surface-sterilized and monosporic isolation was conducted as described above. The same fungus was reisolated from the lesions of symptomatic leaves, and its identity was confirmed by molecular and morphological approaches, thus fulfilling Koch’s postulates. Chlorothalonil and Boscalid can be used to effectively control Corynespora leaf spot (Chairin T et al.2017). To our knowledge, this is the first report of leaf spot caused by C. cassiicola on L. styraciflua in China.

scholarly journals First Report of Corynespora Leaf Spot on Beach Vitex Caused by Corynespora cassiicola in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (11) ◽  
pp. 1512-1512 ◽  
Author(s):  
J. H. Park ◽  
M. J. Park ◽  
S. H. Lee ◽  
C. K. Lee ◽  
H. D. Shin
Keyword(s):  
Invasive Species ◽  
Leaf Spot ◽  
Native Species ◽  
Invasive Plant ◽  
Sand Dunes ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Corynespora Cassiicola ◽  
Single Spore ◽  
Leaf Spots

Beach vitex, Vitex rotundifolia L. fil., is a perennial that grows in temperate and tropical areas of the Pacific. In areas where it has been introduced outside of its native range, beach vitex has proven to be an invasive species. This plant dominates dune ecosystems leading to a reduction in the prevalence of native species (1). In October 2010, previously unknown leaf spots were observed on the beach vitex growing on sand dunes in Incheon City of Korea. The same symptoms were repeated in 2011 and 2012. In September 2012, the same leaf spots were found on the beach vitex in Samcheok and Gyeongju in Korea. The symptoms usually started as small, dark brown to purplish leaf spots with more or less concentric rings, eventually causing leaf blights or yellowing with 50% or more defoliation by the end of September. Representative samples (n = 6) were deposited in the Korea University Herbarium (KUS). Conidiophores of the fungus observed microscopically on the leaf spots were erect, brown to dark brown, single or occasionally in clusters, 80 to 500 × 5 to 9 μm, and mostly arose on the abaxial surface of symptomatic leaves. Conidia were borne singly or in short chains of 2 to 4, ranging from cylindrical to broadest at the base and tapering apically, straight to slightly curved, pale olivaceous brown, 1 to 12 pseudoseptate, 50 to 250 × 8 to 18 μm, each with a conspicuous thickened hilum. On potato dextrose agar (PDA), single-spore cultures of two isolates were identified as Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei on the basis of morphological and cultural characteristics (3). Two monoconidial isolates were preserved at the Korean Agricultural Culture Collection (Accession Nos. KACC45712 and KACC46953). Isolate KACC45712 was used for molecular works and pathogenicity test. Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequence of 520 bp was deposited in GenBank (Accession No. KC987359). A BLAST search in GenBank revealed that the sequence showed 100% identity with those of C. cassiicola (e.g., JQ801302). To conduct a pathogenicity test, a conidial suspension (ca. 2 × 104 conidia/ml) was prepared by harvesting conidia from 2-week-old cultures, and the suspension was sprayed onto the leaves of three healthy seedlings. Inoculated plants were kept in humid chambers for 48 h in a glasshouse. After 5 days, typical leaf spot symptoms started to develop on the leaves of all three inoculated plants. C. cassiicola was reisolated from the lesions, confirming Koch's postulates. Control plants treated with sterile water remained symptomless. C. cassiicola is cosmopolitan with a very wide host range (2,4). To our knowledge, C. cassiicola has not been reported on Vitex spp. anywhere in the world. According to field observations in Korea, Corynespora leaf spot was most severe in August and September, especially following a prolonged period of moist weather. C. cassiicola may be a potential biocontrol agent for this highly invasive species. References: (1) M. C. Cousins et al. Invasive Plant Sci. Manag. 3:340, 2010. (2) L. J. Dixon et al. Phytopathology 99:1015, 2009. (3) M. B. Ellis. Dematiaceous Hyphomycetes. Commonw. Mycol. Inst.: Kew, UK, 1971. (4) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved April 30, 2013.

scholarly journals First Report of Botrytis cinerea on Pansy Flowers in Buenos Aires

Plant Disease ◽  
2004 ◽  
Vol 88 (10) ◽  
pp. 1164-1164
Author(s):  
M. C. Rivera ◽  
S. E. Lopez
Keyword(s):  
Botrytis Cinerea ◽  
Buenos Aires ◽  
Rapid Development ◽  
Pathogenic Fungi ◽  
Gray Mold ◽  
Conidial Suspension ◽  
New Host ◽  
Disease Symptoms ◽  
Plastic Bags ◽  
Pathogenicity Tests

Pansy (Viola × wittrockiana) is an ornamental annual plant produced as a potted plant in greenhouses around Buenos Aires, Argentina. Flower rot with signs of gray mold was observed on pansy cv. Crown during the autumn of 2003. Diseased tissues were surface sterilized by immersion in 2% NaOCl for 1 min, placed on 2% potato dextrose agar (PDA), and incubated at 22°C. Fungal mycelia were initially white and became gray after 72 h. After 4 days, colonies were 4 cm in diameter and sporulated profusely. Black sclerotia developed after 7 days. Mycelia were septate with dark branched conidiophores bearing unicellular, ellipsoid, hyaline conidia that measured 8 to 12 × 6 to 8 μm in botryose heads. These characteristics agree with Botrytis cinerea Pers.:Fr. (1). Pathogenicity tests were performed by spraying 10 healthy pansy plants during bloom with 3 ml of a conidial suspension (106 conidia per ml) per plant. Controls were treated with sterilized distilled water only. Plants were covered with plastic bags for 2 days and incubated at 18 to 22°C. The flowers developed water-soaked lesions between 4 and 6 days after inoculation. Fifty percent of the flowers were pendulous because flower blight reached the peduncle. The pathogen was reisolated from diseased flowers after superficial sterilization with 2% NaOCl and isolated on PDA. Gray mold has a rapid development during bloom, and the pathogen was able to enter undamaged flower tissues. No disease symptoms were observed on leaves. This report adds pansy as a new host of B. cinerea to a previous list of ornamentals grown in Argentina where gray mold was observed. Reference: (1) M. V. Ellis and J. M. Waller. Sclerotinia fuckeliana (condial state: Botrytis cinerea). No. 431 in: Descriptions of Pathogenic Fungi and Bacteria, CMI, Kew, Surrey, UK, 1974.

scholarly journals First Report of Leaf Spot Caused by Corynespora cassiicola on Rose of Sharon in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 847-847 ◽  
Author(s):  
S. T. Seo ◽  
J. H. Park ◽  
S. E. Cho ◽  
H. D. Shin
Keyword(s):  
Leaf Spot ◽  
Brown Spot ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Corynespora Cassiicola ◽  
Sterile Water ◽  
Single Spore ◽  
First Report ◽  
Leaf Spots ◽  
Leaf Yellowing

Rose of Sharon, Hibiscus syriacus L., is a flowering shrub in the family Malvaceae planted as the national flower of South Korea. In September 2012, previously unknown leaf spots with premature defoliation were observed on dozens of Rose of Sharon plants growing in the shaded area in a park of Dongducheon, Korea. The same symptoms were found on Rose of Sharon in several localities of Korea in 2012. The symptoms usually started as small, dark brown to grayish leaf spots, eventually causing leaf yellowing with significant premature defoliation. The diseased leaves retained for a while green color at the margin of the spots. Representative samples (n = 5) were deposited in the Korea University Herbarium (KUS). Conidiophores of the fungus observed microscopically on the leaf spots were erect, brown to dark brown, single or in clusters, amphigenous but mostly hypophyllous, and measured 80 to 400 × 5 to 10 μm. Conidia were borne singly or in short chains, ranging from cylindrical to broadest at the base and tapering apically, straight to slightly curved, pale olivaceous brown, 2 to 16 pseudoseptate, 50 to 260 × 9 to 20 μm, each with a conspicuous thickened hilum. On potato dextrose agar, single-spore cultures of two isolates were identified as Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei on the basis of morphological and cultural characteristics (1,2). Two monoconidial isolates were preserved at the Korean Agricultural Culture Collection (KACC46956 and KACC46957). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequences of 520 bp were deposited in GenBank (Accession Nos. KC193256, KC193257). A BLAST search in GenBank revealed that the sequences showed 100% identity with those of numerous C. cassiicola isolates from diverse substrates. To conduct a pathogenicity test, a conidial suspension (ca. 2 × 104 conidia/ml) was prepared in sterile water by harvesting conidia from 2-week-old cultures of KACC46956, and the suspension was sprayed onto the leaves of three healthy 2-year-old plants. Inoculated plants were kept in humid chambers for the first 48 h and thereafter placed in the glasshouse. After 10 days, typical leaf spot symptoms developed on the leaves of all three inoculated plants. C. cassiicola was reisolated from the lesions, confirming Koch's postulates. Control plants treated with sterile water remained symptomless. C. cassiicola is cosmopolitan with a very wide host range (1,2). Though Corynespora hibisci Goto was recorded to be associated with brown spot disease of H. syriacus in Japan (4), there is no previous record of C. cassiicola on H. syriacus (3). To our knowledge, this is the first report of Corynespora leaf spot on Rose of Sharon in Korea. According to our field observations in Korea, this disease was found in August and September, following a prolonged period of moist weather. Severe infection resulted in leaf yellowing and premature defoliation, reducing tree vigor and detracting the beauty of green leaves. References: (1) L. J. Dixon et al. Phytopathology 99:1015, 2009. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonw. Mycol. Inst., Kew, UK, 1971. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved November 22, 2012. (4) K. Goto. Ann. Phytopathol. Soc. Japan 12:14, 1942.

scholarly journals First Report of a Leaf Spot Disease of Bells-of-Ireland (Moluccella laevis) Caused by Cercospora apii in California

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 203-203
Author(s):  
S. T. Koike ◽  
S. A. Tjosvold ◽  
J. Z. Groenewald ◽  
P. W. Crous
Keyword(s):  
Leaf Spot ◽  
Sequence Data ◽  
Disease Incidence ◽  
Leaf Spot Disease ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Initial Symptoms

Bells-of-Ireland (Moluccella laevis) (Lamiaceae) is an annual plant that is field planted in coastal California (Santa Cruz County) for commercial cutflower production. In 2001, a new leaf spot disease was found in these commercially grown cutflowers. The disease was most serious in the winter-grown crops in 2001 and 2002, with a few plantings having as much as 100% disease incidence. All other plantings that were surveyed during this time had at least 50% disease. Initial symptoms consisted of gray-green leaf spots. Spots were generally oval in shape, often delimited by the major leaf veins, and later turned tan. Lesions were apparent on both adaxial and abaxial sides of the leaves. A cercosporoid fungus having fasciculate conidiophores, which formed primarily on the abaxial leaf surface, was consistently associated with the spots. Based on morphology and its host, this fungus was initially considered to be Cercospora molucellae Bremer & Petr., which was previously reported on leaves of M. laevis in Turkey (1). However, sequence data obtained from the internal transcribed spacer region (ITS1, ITS2) and the 5.8S gene (STE-U 5110, 5111; GenBank Accession Nos. AY156918 and AY156919) indicated there were no base pair differences between the bells-of-Ireland isolates from California, our own reference isolates of C. apii, as well as GenBank sequences deposited as C. apii. Based on these data, the fungus was subsequently identified as C. apii sensu lato. Pathogenicity was confirmed by spraying a conidial suspension (1.0 × 105 conidia/ml) on leaves of potted bells-of-Ireland plants, incubating the plants in a dew chamber for 24 h, and maintaining them in a greenhouse (23 to 25°C). After 2 weeks, all inoculated plants developed leaf spots that were identical to those observed in the field. C. apii was again associated with all leaf spots. Control plants, which were treated with water, did not develop any symptoms. The test was repeated and the results were similar. To our knowledge this is the first report of C. apii as a pathogen of bells-of-Ireland in California. Reference: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Cornell University Press, Ithaca, New York, 1954.

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