First report of Coniella castaneicola causing leaf blight on blueberry (Vaccinium virgatum) in China

Blueberry (Vaccinium virgatum), an economically important small fruit crop, is characterized by its highly nutritive compounds and high content and wide diversity of bioactive compounds (Miller et al. 2019). In September 2020, an unknown leaf blight disease was observed on Rabbiteye blueberry at the Agricultural Science and Technology Park of Jiangxi Agricultural University in Nanchang, China (28°45'51"N, 115°50'52"E). Disease surveys were conducted at that time, the results showed that disease incidence was 90% from a sampled population of 100 plants in the field, and this disease had not been found at other cultivation fields in Nanchang. Leaf blight disease on blueberry caused the leaves to shrivel and curl, or even fall off, which hindered floral bud development and subsequent yield potential. Symptoms of the disease initially appeared as irregular brown spots (1 to 7 mm in diameter) on the leaves, subsequently coalescing to form large irregular taupe lesions (4 to 15 mm in diameter) which became curly. As the disease progressed, irregular grey-brown and blighted lesion ran throughout the leaf lamina from leaf tip to entire leaf sheath and finally caused dieback and even shoot blight. To identify the causal agent, 15 small pieces (5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface-sterilized in 75% ethanol solution for 30 sec and 0.1% mercuric chloride solution for 2 min, rinsed three times with sterile distilled water, and then incubated on potato dextrose agar (PDA) at 28°C for 5-7 days in darkness. Five fungal isolates showing similar morphological characteristics were obtained as pure cultures by single-spore isolation. All fungal colonies on PDA were white with sparse creeping hyphae. Pycnidia were spherical, light brown, and produced numerous conidia. Conidia were 10.60 to 20.12 × 1.98 to 3.11 µm (average 15.27 × 2.52 µm, n = 100), fusiform, sickle-shaped, light brown, without septa. Based on morphological characteristics, the fungal isolates were suspected to be Coniella castaneicola (Cui 2015). To further confirm the identity of this putative pathogen, two representative isolates LGZ2 and LGZ3 were selected for molecular identification. The internal transcribed spacer region (ITS) and large subunit (LSU) were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004) and LROR/LR7 (Castlebury and Rossman 2002). The sequences of ITS region (GenBank accession nos. MW672530 and MW856809) showed 100% identity with accessions numbers KF564280 (576/576 bp), MW208111 (544/544 bp), MW208112 (544/544 bp) of C. castaneicola. LSU gene sequences (GenBank accession nos. MW856810 to 11) was 99.85% (1324/1326 bp, 1329/1331 bp) identical to the sequences of C. castaneicola (KY473971, KR232683 to 84). Pathogenicity was tested on three blueberry varieties (‘Rabbiteye’, ‘Double Peak’ and ‘Pink Lemonade’), and four healthy young leaves of a potted blueberry of each variety with and without injury were inoculated with 20 μl suspension of prepared spores (106 conidia/mL) derived from 7-day-old cultures of LGZ2, respectively. In addition, four leaves of each variety with and without injury were sprayed with sterile distilled water as a control, respectively. The experiment was repeated three times, and all plants were incubated in a growth chamber (a 12h light and 12h dark period, 25°C, RH greater than 80%). After 4 days, all the inoculated leaves started showing disease symptoms (large irregular grey-brown lesions) as those observed in the field and there was no difference in severity recorded between the blueberry varieties, whereas the control leaves showed no symptoms. The fungus was reisolated from the inoculated leaves and confirmed as C. castaneicola by morphological and molecular identification, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. castaneicola causing leaf blight on blueberries in China. The discovery of this new disease and the identification of the pathogen will provide useful information for developing effective control strategies, reducing economic losses in blueberry production, and promoting the development of the blueberry industry.

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First report of Curvularia plantarum causing leaf spot on sweet potato (Ipomoea batatas) in China

Plant Disease ◽

10.1094/pdis-08-21-1665-pdn ◽

2021 ◽

Author(s):

Jiahao Lai ◽

Tongke Liu ◽

Bing Liu ◽

Weigang Kuang ◽

Shuilin Song

Keyword(s):

Sweet Potato ◽

Molecular Identification ◽

Leaf Spot ◽

Ipomoea Batatas ◽

Morphological Characteristics ◽

Distilled Water ◽

Gene Sequences ◽

First Report ◽

Potted Plants ◽

Fungal Isolates

Sweet potato [Ipomoea batatas (L.) Lam], is an extremely versatile vegetable that possesses high nutritional values. It is also a valuable medicinal plant having anti-cancer, antidiabetic, and anti-inflammatory activities. In July 2020, leaf spot was observed on leaves of sweet potato in Nanchang, China (28°45'51"N, 115°50'52"E), which affected the growth and development of the crop and caused tuberous roots yield losses of 25%. The disease incidence (total number of diseased plants / total number of surveyed plants × 100%) was 57% from a sampled population of 100 plants in the field. Symptomatic plants initially exhibited small, light brown, irregular-shaped spots on the leaves, subsequently coalescing to form large irregular brown lesions and some lesions finally fell off. Fifteen small pieces (each 5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface sterilized in 75% ethanol solution for 30 sec and 0.1% mercuric chloride solution for 2 min, rinsed three times with sterile distilled water and incubated on potato dextrose agar (PDA) plates at 28°C in darkness. A total of seven fungal isolates with similar morphological characteristics were obtained as pure cultures by single-spore isolation. After 5 days of cultivation at 28°C, dark brown or blackish green colonies were observed, which developed brown, thick-walled, simple, or branched, and septate conidiophores. Conidia were 18.28 to 24.91 × 7.46 to 11.69 µm (average 21.27 × 9.48 µm, n = 100) in size, straight or slightly curved, middle cell unequally enlarged, brown to dark brown, apical, and basal cells slightly paler than the middle cells, with three septa. Based on morphological characteristics, the fungal isolates were suspected to be Curvularia plantarum (Raza et al. 2019). To further confirm the identification, three isolates (LGZ1, LGZ4 and LGZ5) were selected for molecular identification. The internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate-dehydrogenase (GAPDH), and translation elongation factor 1-alpha (EF1-α) genes were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004), gpd1/gpd2 (Berbee et al. 1999), EF-983F/EF-2218R (Rehner and Buckley 2005), respectively. The sequences of ITS region of the three isolates (accession nos. MW581905, MZ209268, and MZ227555) shared 100% identity with those of C. plantarum (accession nos. MT410571-72, MN044754-55). Their GAPDH gene sequences were identical (accession nos. MZ224017-19) and shared 100% identity with C. plantarum (accession nos. MN264120, MT432926, and MN053037-38). Similarly, EF1-α gene sequences were identical (accession nos. MZ224020-22) and had 100% identity with C. plantarum (accession nos. MT628901, MN263982-83). A maximum likelihood phylogenetic tree was built based on concatenated data from the sequences of ITS, GAPDH, and EF-1α by using MEGA 5. The three isolates LGZ1, LGZ4, and LGZ5 clustered with C. plantarum. The fungus was identified as C. plantarum by combining morphological and molecular characteristics. Pathogenicity tests were conducted by inoculating a conidial suspension (106 conidia/ml) on three healthy potted I. batatas plants (five leaves wounded with sterile needle of each potted plant were inoculated). In addition, fifteen wounded leaves of three potted plants were sprayed with sterile distilled water as a control. All plants were maintained in a climate box (12 h light/dark) at 25°C with 80% relative humidity. All the inoculated leaves started showing light brown flecks after 7 days, whereas the control leaves showed no symptoms. The pathogenicity test was conducted three times. The fungus was reisolated from all infected leaves of potted plants and confirmed as C. plantarum by morphological and molecular identification, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. plantarum causing leaf spot on sweet potato in China. The discovery of this new disease and the identification of the pathogen will contribute to the disease management, provide useful information for reducing economic losses caused by C. plantarum, and lay a foundation for the further research of resistance breeding.

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First Report of Flyspeck Caused by Zygophiala wisconsinensis on Sweet Persimmon Fruit in Korea

Plant Disease ◽

10.1094/pdis-12-10-0917 ◽

2011 ◽

Vol 95 (5) ◽

pp. 616-616 ◽

Cited By ~ 1

Author(s):

J. Kim ◽

O. Choi ◽

J.-H. Kwon

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Rdna ◽

Control Treatment ◽

Diospyros Kaki ◽

Distilled Water ◽

First Report ◽

Persimmon Fruit ◽

Fungal Isolates ◽

Agar Disc

Sweet persimmon (Diospyros kaki L.), a fruit tree in the Ebenaceae, is cultivated widely in Korea and Japan, the leading producers worldwide (2). Sweet persimmon fruit with flyspeck symptoms were collected from orchards in the Jinju area of Korea in November 2010. The fruit had fungal clusters of black, round to ovoid, sclerotium-like fungal bodies with no visible evidence of a mycelial mat. Orchard inspections revealed that disease incidence ranged from 10 to 20% in the surveyed area (approximately 10 ha) in 2010. Flyspeck symptoms were observed on immature and mature fruit. Sweet persimmon fruit peels with flyspeck symptoms were removed, dried, and individual speck lesions transferred to potato dextrose agar (PDA) and cultured at 22°C in the dark. Fungal isolates were obtained from flyspeck colonies on 10 sweet persimmon fruit harvested from each of three orchards. Fungal isolates that grew from the lesions were identified based on a previous description (1). To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA sequence of a representative isolate was amplified and sequenced using primers ITS1 and ITS4 (4). The resulting 552-bp sequence was deposited in GenBank (Accession No. HQ698923). Comparison with ITS rDNA sequences showed 100% similarity with a sequence of Zygophiala wisconsinensis Batzer & Crous (GenBank Accession No. AY598855), which infects apple. To fulfill Koch's postulates, mature, intact sweet persimmon fruit were surface sterilized with 70% ethanol and dried. Three fungal isolates from this study were grown on PDA for 1 month. A colonized agar disc (5 mm in diameter) of each isolate was cut from the advancing margin of a colony with a sterilized cork borer, transferred to a 1.5-ml Eppendorf tube, and ground into a suspension of mycelial fragments and conidia in a blender with 1 ml of sterile, distilled water. The inoculum of each isolate was applied by swabbing a sweet persimmon fruit with the suspension. Three sweet persimmon fruit were inoculated per isolate. Three fruit were inoculated similarly with sterile, distilled water as the control treatment. After 1 month of incubation in a moist chamber at 22°C, the same fungal fruiting symptoms were reproduced as observed in the orchards, and the fungus was reisolated from these symptoms, but not from the control fruit, which were asymptomatic. On the basis of morphological characteristics of the fungal colonies, ITS sequence, and pathogenicity to persimmon fruit, the fungus was identified as Z. wisconsinensis (1). Flyspeck is readily isolated from sweet persimmon fruit in Korea and other sweet persimmon growing regions (3). The exposure of fruit to unusual weather conditions in Korea in recent years, including drought, and low-temperature and low-light situations in late spring, which are favorable for flyspeck, might be associated with an increase in occurrence of flyspeck on sweet persimmon fruit in Korea. To our knowledge, this is the first report of Z. wisconsinensis causing flyspeck on sweet persimmon in Korea. References: (1) J. C. Batzer et al. Mycologia 100:246, 2008. (2) FAOSTAT Database. Retrieved from http://faostat.fao.org/ , 2008. (3) H. Nasu and H. Kunoh. Plant Dis. 71:361, 1987. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990.

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First Report of Curvularia Leaf Blight on Curcuma wenyujin Caused by Curvularia clavata in China

Plant Disease ◽

10.1094/pdis-04-12-0392-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 138-138 ◽

Cited By ~ 4

Author(s):

X. Y. Chen ◽

J. D. Feng ◽

Z. Su ◽

C. Sui ◽

X. Huang

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Leaf Blight ◽

Hainan Province ◽

Continuous Cropping ◽

Single Spore ◽

Chinese Medicinal Herb ◽

First Report ◽

Causal Pathogen ◽

Blight Disease

Curcuma wenyujin Y.H. Chen & C. Ling is a traditional Chinese medicinal herb in the Zingiberaceae family. Commonly known as Wen yujin, the root is widely used for alleviating pain and protecting the liver. A severe leaf blight disease was observed in three C. wenyujin farms in Hainan Province of China in October 2010. The obvious symptoms of leaf blight, yellow to brown irregular lesions (1 to 20 cm) on C. wenyujin, usually began at the tips of leaves and the main veins. This disease, especially severe from August to October, caused heavy damage and 100% of mature plants (10 months old) in farms were infected. The disease was most severe when continuous cropping was performed and showed slight improvement when rotation was adopted. Farmers usually sprayed carbendazim (50% WP) and thiophanate-methyl (70% WP) to control this disease, but these treatments were not effective. To isolate the causal pathogen, diseased plants were collected in October 2010 from a field of the Hainan Branch Institute of Medicinal Plant Development in Hainan Province. Lesion tissue was removed from the border between symptomatic and healthy tissue, surface sterilized in 75% ethanol for 1 min, washed in three changes of sterile distilled water, transferred to potato dextrose agar (PDA) plates, and incubated at 28°C for 7 days. Single spore cultures of five isolates were obtained and identified as Curvularia clavata based on morphological characteristics (1). Conidia measured 20 to 29 × 7.5 to 10.5 μm (n = 100), were curved, 3-septate, and the third cell from the base was larger and darker than the others. Mycelia of single spore cultures growing on PDA for 5 days were used for DNA extraction using a plant genomic DNA kit (TIANGEN, Beijing). The internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1 and ITS4. The amplicons were 562 bp in length (GenBank Accession No. JQ730852) and had 99% nucleotide identity with the GenBank Accession No. JN021115 and AF071336 of C. clavata. Pathogenicity tests were conducted using fresh and healthy detached Curcuma wenyujin leaves. Mycelial discs (10 mm) removed from a 5-day-old colony on PDA were used for inoculation. Each isolate was inoculated on three distinct leaves (two distinct inoculations per leaf). Three additional leaves inoculated with sterile PDA discs were used as control. Inoculated leaves were covered with a polythene film to maintain high humidity. Leaves in trays were kept in a growth chamber at 28°C and observed for symptom appearance every day. Five days after inoculation, inoculated leaves developed blight symptoms similar to those observed on naturally infected leaves. No symptoms were observed on non-inoculated leaves. C. clavata was reisolated from the inoculated leaves, thus fulfilling Koch's postulates. C. clavata has been previously reported to be economically important on a number of other hosts (2). To our knowledge, this is the first report of Curvularia leaf blight on Curcuma wenyujin caused by C. clavata in China. References: (1) A. M Mandokhot et al. Eur. J. Plant Pathol.78:65, 1972. (2) T. Y. Zhang et al. Flora fungorum sinicorum: Beijing, China, 2010.

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First report of fruit blight caused by Alternaria alternata on sesame in Northeast China

Plant Disease ◽

10.1094/pdis-01-21-0047-pdn ◽

2021 ◽

Author(s):

Hongsen Cheng ◽

De Xue Gao ◽

Huijie Sun ◽

Yanbin Na ◽

Jing Xu

Keyword(s):

Alternaria Alternata ◽

Morphological Characteristics ◽

Its Region ◽

Liaoning Province ◽

Oilseed Crop ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Health Products ◽

Blight Disease

Sesame (Sesamum indicum L.) is an important oilseed crop in China and it is also used in food and health products. In August of 2019, a blight sesame fruit was observed in a field of Liaoyang city, Liaoning province of China. Initial disease symptoms consisted of brown or dark brown spots on fruit. With time, lesions coalesced and the whole fruit turned dark brown or black. Most of the diseased fruit had thin and small, deformed, necrotic, hardened cracked epidermal lesions. Lesions were also produced on stem and petioles leading to leaf abscission. The disease results in premature fruit death, and in turn, considerable yield losses. To determine the causal agent, symptomatic fruit with developing lesions were collected, and surface sterilized in 2% NaClO for 3 min, rinsed three times in distilled water, and plated onto PDA medium. After incubation at 25°C for 5 days, a dark olivaceous fungus with abundant, branched, brown to black, and septate hyphae was consistently isolated. Twenty single spores were separated with an inoculation needle under stereomicroscope. The conidia were in chains, brown, obclavate, ovoid or ellipsoid, with 1-6 transverse septa and 0-4 longitudinal or oblique septa 12.5 to 45 × 6.5 to 14.5 μm in size. Conidiophores were septate, light brown to olive brown, measuring 22-60 μm × 2-4 μm. The morphological characteristics of the 20 isolates all matched the description of Alternaria alternata (Simmons, 2007). The internal transcribed spacer (ITS) region of rDNA of 15 isolates was amplified using primers ITS1/ITS4 (White et al. 1990) and EF1-728F/EF1-986R (Carbone et al. 1999) and sequenced. Identical sequences were obtained and the sequence of the isolate ZMHG12 was submitted to GenBank (Accession no. MW418181 and MW700316). BLAST analysis of the sequences of the isolates of ZMHG12 showed 100% to A. alternata (KP739875 and LC132712). In pathogenicity tests, a conidial suspension (2.5 × 105 conidia per ml) was prepared from 7 days-old cultures of isolate ZMHG12 grown on PDA at 25°C. Fruit of 10 two-month-old potted sesame plants (Variety “Liaozhi 8”) were sprayed with the conidia suspension until runoff. Another 10 plants sprayed with distilled water to served as non-inoculated controls. All plants were maintained for 48 h in a humid chamber with a temperature of 25°C to 26°C, and then moved to a greenhouse. Ten days after inoculation, all fruit of inoculated plants exhibited symptoms similar to those observed in the field and non-inoculated control plants remained symptomless. The experiment was repeated twice with similar results. A. alternata has been reported as a pathogen caused leaf blight disease of sesame in Pakistan (Nayyar et al. 2017). To our knowledge, this is the first report of A.alternata causing fruit blight of sesame in China. To date, we have observed the disease on sesames in fields of Fuxin, Chaoyang and Tieling city in Liaoning Province, and Tongliao city in Inner Mongolia of China, and it has become an important disease in sesame production of China. References : Simmons E. G. 2007. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands. White T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego. Carbone I., et al. 1999. Mycologia, 91: 553-556. Nayyar, B. G., et al. 2017. Plant Pathology Journal, 33 (6): 543-553.

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First Report of a Chaetomella sp. Causing a Leaf Spot on Sansevieria trifasciata in China

Plant Disease ◽

10.1094/pdis-10-12-0993-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 992-992 ◽

Cited By ~ 4

Author(s):

Y. L. Li ◽

Z. Zhou ◽

W. Lu ◽

J. R. Ye

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Aerial Mycelium ◽

Control Treatment ◽

Distilled Water ◽

First Report ◽

Potted Plants ◽

Fungal Isolates

Sansevieria trifasciata originates from tropical West Africa. It is widely planted as a potted ornamental in China for improving indoor air quality (1). In February 2011, leaves of S. trifasciata plants in an ornamental market of Anle, Luoyang City, China, were observed with sunken brown lesions up to 20 mm in diameter, and with black pycnidia present in the lesions. One hundred potted plants were examined, with disease incidence at 20%. The symptomatic leaves affected the ornamental value of the plants. A section of leaf tissue from the periphery of two lesions from a plant was cut into 1 cm2 pieces, soaked in 70% ethanol for 30 s, sterilized with 0.1% HgCl2 for 2 min, then washed five times in sterilized distilled water. The pieces were incubated at 28°C on potato dextrose agar (PDA). Colonies of two isolates were brown with submerged hyphae, and aerial mycelium was rare. Abundant and scattered pycnidia were reniform, dark brown, and 200 to 350 × 100 to 250 μm. There were two types of setae on the pycnidia: 1) dark brown setae with inward curved tops, and 2) straight, brown setae. Conidia were hyaline, unicellular, cylindrical, and 3.75 to 6.25 × 1.25 to 2.50 μm. Morphological characteristics suggested the two fungal isolates were a Chaetomella sp. To confirm pathogenicity, six mature leaves of a potted S. trifasciata plant were wounded with a sterile pin after wiping each leaf surface with 70% ethanol and washing each leaf with sterilized distilled water three times. A 0.5 cm mycelial disk cut from the margin of a 5-day-old colony on a PDA plate was placed on each pin-wounded leaf, ensuring that the mycelium was in contact with the wound. Non-colonized PDA discs were placed on pin-wounded leaves as the control treatment. Each of two fungal isolates was inoculated on two leaves, and the control treatment was done similarly on two leaves. The inoculated plant was placed in a growth chamber at 28°C with 80% relative humidity. After 7 days, inoculated leaves produced brown lesions with black pycnidia, but no symptoms developed on the control leaves. A Chaetomella sp. was reisolated from the lesions of inoculated leaves, but not from the control leaves. An additional two potted plants were inoculated using the same methods as replications of the experiment, with identical results. To confirm the fungal identification, the internal transcribed spacer (ITS) region of rDNA of the two isolates was amplified using primers ITS1 and ITS4 (2) and sequenced. The sequences were identical (GenBank Accession No. KC515097) and exhibited 99% nucleotide identity to the ITS sequence of an isolate of Chaetomella sp. in GenBank (AJ301961). To our knowledge, this is the first report of a leaf spot of S. trifasciata caused by Chaetomella sp. in China as well as anywhere in the world. References: (1) X. Z. Guo et al. Subtropical Crops Commun. Zhejiang 27:9, 2005. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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First report of root rot of Schisandra chinensis caused by Fusarium acuminatum in Northeast China

Plant Disease ◽

10.1094/pdis-05-21-1052-pdn ◽

2021 ◽

Author(s):

Baoyu Shen ◽

Wensong Sun ◽

Kun Liu ◽

Jing Tian Zhang

Keyword(s):

Root Rot ◽

Apical Cell ◽

Morphological Characteristics ◽

Liaoning Province ◽

Effective Control ◽

Distilled Water ◽

Conidial Suspension ◽

Schisandra Chinensis ◽

First Report ◽

Fusarium Acuminatum

Wuweizi [Schisandra chinensis（Turcz.）Baill.] is used for traditional medicine in northeastern China. In August of 2019, root rot of S. chinensis with an incidence of 30%-50% was observed in a commercial field located in Liaozhong city (41º29’57” N, 122º52’33” E) in the Liaoning province of China. The diseased plants were less vigorous, stunted, and had leaves that turned yellow to brown. Eventually, the whole plant wilted and died. The diseased roots were poorly developed with brown lesion and eventually they would rot. To determine the causal agent, symptomatic roots were collected, small pieces of root with typical lesions were surface sterilized in 2% NaOCl for 3 min, rinsed three times in distilled water, and then plated onto PDA medium. After incubation at 26°C for 5 days, whitish-pink or carmine to rose red colonies on PDA were transferred to carnation leaf agar (CLA). Single spores were isolated with an inoculation needle using a stereomicroscope. Five single conidia isolates obtained from the colonies were incubated at 26°C for 7 days, abundant macroconidia were formed in sporodochia. Macroconidia were falcate, slender, with a distinct curve to the latter half of the apical cell, mostly 3 to 5 septate, measuring 31.3 to 47.8 × 4.8 to 7.5µm (n=50). Microconidia were oval and irregular ovals, 0-1 septate, measuring 5.0 to 17.5 × 2.5 to 17.5µm (n=50). Chlamydospores formed in chains on within or on top of the mycelium. Morphological characteristics of the isolates were in agreement with Fusarium acuminatum (Leslie and Summerell, 2006). To confirm the identity, the partial sequence of the translation elongation factor 1 alpha (TEF1-á) gene of five isolates was amplified using the primers EF-1(ATGGGTAAGGARGACAAG) and EF-2 (GGARGTACCAGTSATCATGTT) (O’Donnell et al. 2015 ) and sequenced. The rDNA internal transcribed spacer (ITS) region for the five isolates was also amplified using the primers ITS1 (TCCGTAGGTGAACCTGCGG) and ITS4 (TCCTCCGCTATTGATATGC) (White et al.1990) and sequenced. The identical sequences were obtained, and one representative sequence of isolate WW31-5 was submitted to GenBank. BLASTn analysis of the TEF-á sequence (MW423624) and ITS sequence (MZ145386), revealed 100%（708/685bp, 563/563bp）sequence identity to F. acuminatum MH595498 and MW560481, respectively. Pathogenicity tests were conducted in greenhouse. Inoculums of F. acuminatum was prepared from the culture of WW31-5 incubated in 2% mung beans juice on a shaker (140 rpm) at 26°C for 5 days. Ten roots of 2-years old plants of S. chinensis were immersed in the conidial suspension (2 × 105 conidia/ml) for 6 hours, and another ten roots immersed in sterilized distilled water in plastic bucket for 6 hours. All these plants were planted into pots with sterilized field soil (two plants per pot). Five pots planted with inoculated plants and another five pots planted with uninoculated plants served as controls. All ten pots were maintained in a greenhouse at 22-26°C for 21 days and irrigated with sterilized water. The leaves of the inoculated plants became yellow，gradually dried up, eventually finally all the aboveground parts died. The roots of the inoculated plants were rotted. Non-inoculated control plants had no symptoms. F. acuminatum was reisolated from the roots of inoculated plants and had morphology identical to the original isolate. The experiment was repeated twice with similar results. F. acuminatum has been reported as a pathogen caused root rot of ginseng (Wang et al. 2016) and not reported on Wuweizi in China. To our knowledge, this is the first report of root rot of S. chinensis caused by F. acuminatum. We have also observed the disease at Benxi city of Liaoning Province in 2020 and it has become an important disease in production of S. chinensis and the effective control method should be adopted to reduce losses.

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First Report of Leaf Blight Caused by Phomopsis ipomoeae-batatas on Sweet Potato in Korea

Plant Disease ◽

10.1094/pdis-06-12-0563-pdn ◽

2012 ◽

Vol 96 (11) ◽

pp. 1701-1701 ◽

Cited By ~ 1

Author(s):

J. H. Park ◽

M. J. Park ◽

K. S. Han ◽

H. D. Shin

Keyword(s):

Sweet Potato ◽

Ipomoea Batatas ◽

Morphological Characteristics ◽

Leaf Blight ◽

Economic Losses ◽

Minor Importance ◽

Conidial Suspension ◽

First Report ◽

Close Phylogenetic Relationship ◽

Two Samples

Ipomoea batatas (L.) Lam., belonging to the Convolvulaceae, is widely cultivated and used as an industrial resource as well as for food and feed worldwide (2). In September 2010, an unknown leaf blight was observed on leaves in Hoengseong County and Jecheon City in Korea. Symptoms were mostly observed in older leaves as cream to tan-brown lesions surrounded by purplish brown-to-dark brown margin. Each lesion was circular to irregular, not exceeding 10 mm, but coalesced to form larger lesions. Necrotic tissue fell out giving rise to shot-holes. A number of black pycnidia were present in the lesions of diseased leaves. The same symptoms were observed at several localities in Korea during 2010 and 2011 seasons. The voucher specimens (n = 5) were preserved in the Korea University Herbarium (KUS). Two isolates were obtained from the two samples (KUS-F25274 and KUS-F25361) and deposited in the Korean Agricultural Culture Collection (Accession Nos. KACC45680 and KACC45702). Pycnidia were amphigenous, but mostly epigenous, scattered, dark brown-to-rusty brown, globose, embedded in host tissue or partly erumpent, 110 to 170 μm in diameter, and with an ostiole of 25 to 40 μm in diameter. Alpha conidia were aseptate, lageniform, biguttulate, hyaline, and 5.5 to 8.0 × 3.5 to 4.5 μm. Beta conidia were absent. Based on the morphological characteristics, the fungus was consistent with Phomopsis ipomoeae-batatas Punith. (1,3). Preliminary identification of the fungal isolate was confirmed by molecular data. Genomic DNA was extracted from the two isolates. The D1/D2 region of 28S rDNA was amplified using the primers LROR and LR7, and sequenced. The resulting sequences of the two isolates were identical to each other, and were deposited in GenBank (Accession Nos. JX157848 and JX157849). A BLAST search showed that there was no matching sequence of P. ipomoeae-batatas. Therefore, these were the first 28S sequences for the species submitted to GenBank. The present sequences showed >98% similarity with 24 entries of Phomopsis spp. and Diaporthe spp. (teleomorph of Phomopsis spp.), indicating their close phylogenetic relationship. Pathogenicity was tested by spraying leaves of three potted plants with a conidial suspension (2 × 106 conidia/ml), which was harvested from a 3-week-old culture on potato dextrose agar. Control leaves were sprayed with sterile water. The plants were placed in a dew chamber at 24°C in darkness and continuous dew for the first 24 h and then moved to a greenhouse bench. After 10 days, leaf blight symptoms that were identical to those observed in the field started to develop on the leaves inoculated with the fungus. No symptoms were observed on control plants. P. ipomoeae-batatas was reisolated from the lesions of inoculated plants, confirming Koch's postulates. Occurrence of leaf blight caused by P. ipomoeae-batatas on sweet potato has been reported in many countries (1,3). To our knowledge, this is the first report of the disease in Korea. The economic losses are of minor importance, because the disease is mostly present toward the end of growing season; however, attention must be paid considering that the pathogen may reduce the quality of vines used as fodder. References: (1) C. A. Clark and J. W. Moyer. Compendium of Sweet Potato Diseases. The American Phytopathological Society. St. Paul, MN, 1988. (2) I. G. Mok et al. J. Plant Biotechnol. 36:202, 2009. (3) E. Punithalingam. Phomopsis ipomoeae-batatas. IMI Descriptions of Fungi and Bacteria. Sheet 739, 1982.

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First Report of Postharvest Fruit Rot Disease of Hardy Kiwifruit Caused by Diaporthe eres in China

Plant Disease ◽

10.1094/pdis-08-20-1705-pdn ◽

2021 ◽

Author(s):

Jian Liu ◽

Xiaomei GUO ◽

Hui Zhang ◽

Yue Cao ◽

QUN SUN

Keyword(s):

Northeast China ◽

Morphological Characteristics ◽

Fruit Rot ◽

Liaoning Province ◽

Economic Losses ◽

Initial Symptom ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Rot Disease

Hardy kiwifruit (Actinidia arguta), as an economically important fruit crop growing in Northeast China with thin, hairless and smooth skin, is susceptible to postharvest decay. In September 2018, infected cultivar Kwilv fruits were obtained from a commercial farm in Liaoning province, northeastern China. The occurring incidence of the rot disease varied from 20% to 90% according to the fruit number in each box during a 7-day-long storage at room temperature, and the initial symptom included a small, soft, chlorosis to light brown lesion and later watery brown lesions. Pure cultures of the same characteristics were obtained from the isolated strains in four rotten fruits on PDA medium. The isolates grew into transparent radial mycelium on PDA in the first two days followed by abundant white, fluffy aerial mycelium. After 14 days, colonies formed white to light brown aerial mycelial mats with gray concentric rings, and they produced gray and embedded pycnidia. Alpha conidia of 4.4 to 8.8 µm × 1.4 to 3.3 µm (n = 50) were abundant in culture, hyaline, aseptate, ellipsoidal to fusiform, while Beta conidia at 20.5 to 28.6 µm × 1.0 to 1.4 µm (n = 50) were hyaline, long, slender, curved to hamate. These morphological characteristics were similar to Diaporthe species (anamorph: Phomopsis spp.) (Udayanga et al. 2014). For identification, DNA was extracted from three single isolates respectively , and the internal transcribed spacer (ITS) region, β-tubulin (BT), and histone (HIS) H3 gene were amplified by using primers ITS1/ITS4 (White et al. 1990), T1/T22 (O'Donnell et al. 1997) and HIS1F/HISR (Gao et al. 2017), respectively. The three isolates produced identical sequences across all three gene regions, which were submitted to NCBI (Genbank accession numbers MT561361, MT561360 and MT855966). Nucleotide BLAST analysis revealed that the ITS sequence shared 99% homology with those of ex-type Diaporthe eres in NCBI GenBank (MG281047.1 and KJ210529.1), so did the BT sequence that had 98% identity to D. eres (MG281256.1 and KJ420799.1) and the HIS 99% identity to D. eres (MG28431.1 and MG281395.1) (Hosseini et al. 2020, Udayanga et al. 2014). Pathogenicity was tested by wound inoculation on the cv. Kwilv fruits. Five mature and healthy fruits were surface-sterilized with 1% NaClO solution, rinsed in sterile distilled water and dried. Every fruit was wounded by penetrate the peel 1-2 mm with a sterile needle, and inoculated with mycelium plugs (5 mm in diameter) of the isolate on PDA, with five inoculated with sterile PDA plugs as controls. Treated fruits were kept in sterilized transparent plastic cans separately under high humidity (RH 90 to 100%) at 28°C. After five days, the same rot symptoms were observed on all fruits inoculated with mycelium while the control remained symptomless. The fungi was re-isolated from the lesions of inoculated fruits and identified as D. eres by sequencing, thus fulfilling Koch's postulates. The pathogenicity experiment was re-performed using D. eres conidial suspension (107 conidia/ml) in sterile distilled water in October 2019 and the same results were obtained. D. eres was recently reported to cause European pear rot in Italy (Bertetti et al. 2018). To our knowledge, this is the first report of D. eres causing a postharvest rot in hardy kiwifruit in China, leading to severe disease and thus huge economic losses in Northeast China. Accordingly, effective measures should be taken to prevent its spreading to other production regions in China.

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A New Leaf Blight Disease Caused by Alternaria jacinthicola on Banana in China

Horticulturae ◽

10.3390/horticulturae8010012 ◽

2021 ◽

Vol 8 (1) ◽

pp. 12

Author(s):

Bin Wang ◽

Yongyan Zhang ◽

Jiapeng Liu ◽

Ou Sheng ◽

Fan Liu ◽

...

Keyword(s):

Molecular Identification ◽

Guangdong Province ◽

Leaf Blight ◽

Economic Losses ◽

Early Symptom ◽

Leaf Spots ◽

Alternaria Species ◽

Blight Disease ◽

Banana Leaves ◽

Identification Analysis

A leaf blight disease with an incidence level of about 50% was found on Robusta banana in Guangdong province of China in September 2020. The early symptom appeared as pale gray to black brown, irregular, small, necrotic lesions mainly on the top 3–5 leaves. Severely infected leaves were withered and necrotic. Two representative fungus strains, strain L1 and strain L2, were isolated from affected banana leaves, and morphological and molecular identification analysis confirmed that the two fungi were both Alternaria jacinthicola. Many Alternaria species have been reported to cause wilting, decay, leaf blight and leaf spots on plants and lead to serious economic losses in their production, including A. alternata, causing leaf blight and leaf sport diseases on banana. The Koch’s postulates of A. jacinthicola causing the leaf blight disease was further fulfilled, which confirmed that it is the causal agent of this disease. To our knowledge, this is the first report of A. jacinthicola causing leaf blight on banana in China.

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First report of chili pepper fruit rot caused by Fusarium incarnatum in China

Plant Disease ◽

10.1094/pdis-09-19-1996-pdn ◽

2021 ◽

Author(s):

Xiao Qin Zhu ◽

Dongmei Liu ◽

Quanchun Hong ◽

Yifang Lu ◽

Dongli Pei

Keyword(s):

Chili Pepper ◽

Fruit Rot ◽

Effective Control ◽

Economic Losses ◽

Hainan Province ◽

Pathogenicity Test ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Pepper Fruit

Pepper (Capsicum annuum L.), with annual production over 1 million tons, is ranked the first vegetable crop in Hainan Province, China. In December 2018, fruit rot of chili pepper , with yield loss of up to 15%, was found in 10 fields (12 hm2) in Yacheng (18°N, 109°E), Hainan Province, China. Water-soaked and soft lesions developed on fruit, with white to light gray fungal mycelium present inside. The diseased fruit turned soft and decayed at the later stages. Diseased tissue was cut into 12 pieces of 0.5×0.5 cm, surface-disinfected with 2% sodium hypochlorite for 2 min, followed by 70% ethanol for 30 s, rinsed with sterile distilled water five times, and plated onto potato dextrose agar (PDA). After growing on PDA for 2 to 3 days at 28°C in an incubator without light, 10 pure culture isolates were obtained. All isolates had abundant dense white aerial mycelia that became beige with age. The macroconidia were slightly curved with four to seven septa, 29.51 to 42.15 × 4.29 to 6.22 μm. Spindle-shaped mesoconidia with three to four septa were abundantly produced, 20.34 to 24.54 × 4.58 to to 11.70 × 2.35 to 3.20 μm. Chlamydospores were absent. Based on the morphological characteristics, the fungus was tentatively identified as Fusarium incarnatum (Leslie and Summerell 2006). An isolate SQHP-01 was chosen for molecular identification and pathogenicity test. Two DNA fragments of the isolate, the internal transcribed spacer (ITS) and translation elongation factor genes (EF-1α) were amplified for sequencing. BLAST analysis showed that sequences of ITS (GenBank acc. no. MN317371) and EF-1α (acc. No. MN928788) had 99.61 to 100% identity with those of known F. incarnatum (MN480497 and KF993969). Phylogenetic analysis was conducted using neighbor-joining algorithm based on ITS and EF-1a genes separately, and the isolate was well clustered with F. incarnatum both with 100% bootstrap support. Pathogenicity test of the isolate were carried out twice on five healthy chili pepper fruit. After surface-disinfection, fruit were wounded at three different points and 20 μl of conidial suspension (106 conidia/ml) were deposited on each wound. Unwounded inoculation was conducted by spreading 100 μl of the suspension on each fruit surface including the pedicel and calyx. The fruit spread with sterile distilled water represented the negative control. All fruit treatments were placed on the moist sterile cotton in moist chambers at 25°C with 16 h light and 8 h darkness. After 4 to 6 days, water-soaked necrotic lesions appeared on the wounded fruit, the symptoms identical to those observed in the field. Water-soaked necrotic lesions developed on the pedicel and calyx of unwounded fruit. No symptoms were observed on the control fruit. The morphology and sequences of re-isolated fungal isolates from the tested peppers were the same as the original isolate. To our knowledge, this is the first report of F. incarnatum (synonym of F. semitectum) causing fruit rot on chili pepper in China. F. incarnatum has been reported to cause root rot of greenhouse pepper in China (Li et al. 2018), fruit rot of bell pepper in Trinidad (Ramdial et al. 2016) and Pakistan (Tariq et al. 2018). Effective control strategies need to be developed to prevent the economic losses caused by the disease in chili pepper.

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