Identification and Pathogenicity of Fungi Associated with Leaf Spot of Muskmelon in Eastern Shandong Province, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xiaoyan Yu ◽  
Jing Zhang ◽  
Xue Zhang ◽  
Xilang Yang ◽  
Xi Xu ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Bipolaris Sorokiniana ◽  
Shandong Province ◽  
Didymella Bryoniae ◽  
Sampling Area ◽  
Exserohilum Rostratum ◽  
Serious Disease ◽  
Production Areas ◽  
Isolated Species

Leaf spot is a serious disease in the growth and development of muskmelon, which can affect its quality and yield. In recent years, Malianzhuang Muskmelon Base, the main muskmelon producing area in Shandong Province, China, has been seriously affected by leaf spot. Since 2018, symptomatic leaves were collected from eleven production areas of this base to determine the pathogens of muskmelon foliar diseases. 200 fungal strains were isolated and 10 genera and 17 species were identified based on morphological characteristics and multi-locus phylogenetic analysis (ITS, GADPH, RPB2, HIS3, EF-1α, and LSU). The most frequently isolated species from each sampling area was Alternaria tenuissima with 77 strains, followed by A. alternata. Pathogenicity experiments showed that A. alternata, A. tenuissima, Fusarium neocosmosporiellum (formerly Neocosmospora vasinfecta), F. acuminatum, Exserohilum rostratum, Bipolaris sorokiniana, and Stagonosporopsis cucurbitacearum (formerly Didymella bryoniae) could cause symptoms highly similar to those of infected leaves observed under natural conditions in the field. Therefore, these fungal isolates are considered to be the primary pathogens causing muskmelon leaf spot, and A. tenuissima and A. alternata were the most common and virulent pathogens in this study. In addition, this is the first study of F. neocosmosporiellum, F. acuminatum, E. rostratum, and B. sorokiniana as pathogens associated to muskmelon leaf spot in China as well as the world.

Dieback and leaf spot in box elder (Acer negundo) caused by Exserohilum rostratum

Plant Disease ◽  
2021 ◽  
Author(s):  
Cheng-Long Liu ◽  
Xiang-rong Zheng ◽  
Fengmao Chen
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Its Region ◽  
Acer Negundo ◽  
Box Elder ◽  
Insect Infestations ◽  
Exserohilum Rostratum ◽  
Systemic Symptoms ◽  
High Winds

Leaf spot and dieback were observed on box elder (Acer negundo) grown in a nursery in Tai'an city, Shandong Province, China, in 2019, with a disease incidence of 86%. The incidence of Exserohilum rostratum isolation was 75% from the shoots and 66.6% from the leaves of field-infected plants. Isolates were identified at the species level on the basis of morphological characteristics and through phylogenetic analysis of concatenated partial sequences of the internal transcribed spacer (ITS) region and cam, gapdh, tef1, rpb2, tub2, and his genes from the Exserohilum isolates. The effects of temperature on the mycelial growth of the E. rostratum isolates were also characterized. In greenhouse tests, seedlings inoculated with the pathogen exhibited systemic symptoms similar to those observed in the field. In pathogenicity experiments on shoots, wounded seedlings were observed to be blighted, suggesting that leaf spot and dieback may develop into more severe blight or dieback when high winds, sudden temperature drops, or insect infestations occur. To our knowledge, this is the first report of dieback and leaf spot caused by E. rostratum on a species of A. negundo.

scholarly journals Isolation and Characterization of Bacillus amyloliquefaciens TL6 as a Biological Control Agent for Peanut Early Leaf Spot Caused by Passalora arachidicola

2021 ◽  
Author(s):  
Chao Zang ◽  
Futao An ◽  
Jinhui Xie ◽  
Ying Lin ◽  
Shuyi Yu ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Bacillus Amyloliquefaciens ◽  
Morphological Characteristics ◽  
Cercospora Arachidicola ◽  
Control Effect ◽  
Commercial Development ◽  
Fermentation Liquid ◽  
Isolation And Characterization ◽  
Field Control ◽  
Production Areas

Abstract Peanut early leaf spot caused by Passalora arachidicola (Cercospora arachidicola), is a worldwide common fungal disease in peanut leaves, which occurs in all production areas in China. To obtain biocontrol resources to control peanut early leaf spot, 60 healthy peanut leaves were collected from major peanut production areas in Liaoning Province. A total of 563 strains were screened from these leaves. Eighteen strains showed differing levels of resistance against P. arachidicola. Among these strains, strain TL6 inhibited the pathogen most strongly, and the diameter of inhibition zone was 64.3 mm. This strain was able to inhibit 10 other types of pathogens. It was identified as Bacillus amyloliquefaciens based on its morphological characteristics, physiological and biochemical reactions and a comparative analysis of its 16S rDNA sequence. The fermentation liquor of strain TL6 was effective at controlling peanut early leaf spot, and the field control effect was above 69.17% after spraying the fermentation liquid of TL6. The field control effect was more than 40.96% after spraying the fermentation liquid diluted 200 times. The field control effect of the TL6 fermentation liquid diluted 200 times and including the addition of 500 gL-1 carbendazim diluted 1000 times inhibited P. arachidicola by 81.33%. The combination of TL6 and carbendazim had a significant synergistic effect. This strain of B. amyloliquefaciens shows promise for commercial development and application.

scholarly journals First Report of Leaf Spot caused by Bipolaris oryzae on Switchgrass in Tennessee

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1654-1654 ◽  
Author(s):  
A. L. Vu ◽  
M. M. Dee ◽  
J. Zale ◽  
K. D. Gwinn ◽  
B. H. Ownley
Keyword(s):  
Leaf Spot ◽  
Panicum Virgatum ◽  
Morphological Characteristics ◽  
Its Region ◽  
Spore Production ◽  
Post Inoculation ◽  
Sterile Water ◽  
Bipolaris Oryzae ◽  
First Report ◽  
Symptomatic Leaf

Knowledge of pathogens in switchgrass, a potential biofuels crop, is limited. In December 2007, dark brown to black irregularly shaped foliar spots were observed on ‘Alamo’ switchgrass (Panicum virgatum L.) on the campus of the University of Tennessee. Symptomatic leaf samples were surface-sterilized (95% ethanol, 1 min; 20% commercial bleach, 3 min; 95% ethanol, 1 min), rinsed in sterile water, air-dried, and plated on 2% water agar amended with 3.45 mg fenpropathrin/liter (Danitol 2.4 EC, Valent Chemical, Walnut Creek, CA) and 10 mg/liter rifampicin (Sigma-Aldrich, St. Louis, MO). A sparsely sporulating, dematiaceous mitosporic fungus was observed. Fungal plugs were transferred to surface-sterilized detached ‘Alamo’ leaves on sterile filter paper in a moist chamber to increase spore production. Conidia were ovate, oblong, mostly straight to slightly curved, and light to olive-brown with 3 to 10 septa. Conidial dimensions were 12.5 to 17 × 27.5 to 95 (average 14.5 × 72) μm. Conidiophores were light brown, single, multiseptate, and geniculate. Conidial production was polytretic. Morphological characteristics and disease symptoms were similar to those described for Bipolaris oryzae (Breda de Haan) Shoemaker (2). Disease assays were done with 6-week-old ‘Alamo’ switchgrass grown from seed scarified with 60% sulfuric acid and surface-sterilized in 50% bleach. Nine 9 × 9-cm square pots with approximately 20 plants per pot were inoculated with a mycelial slurry (due to low spore production) prepared from cultures grown on potato dextrose agar for 7 days. Cultures were flooded with sterile water and rubbed gently to loosen mycelium. Two additional pots were inoculated with sterile water and subjected to the same conditions to serve as controls. Plants were exposed to high humidity by enclosure in a plastic bag for 72 h. Bags were removed, and plants were incubated at 25/20°C with 50 to 60% relative humidity. During the disease assay, plants were kept in a growth chamber with a 12-h photoperiod of fluorescent and incandescent lighting. Foliar leaf spot symptoms appeared 5 to 14 days post-inoculation for eight of nine replicates. Control plants had no symptoms. Symptomatic leaf tissue was processed and plated as described above. The original fungal isolate and the pathogen recovered in the disease assay were identified using internal transcribed spacer (ITS) region sequences. The ITS region of rDNA was amplified with PCR and primer pairs ITS4 and ITS5 (4). PCR amplicons of 553 bp were sequenced, and sequences from the original isolate and the reisolated pathogen were identical (GenBank Accession No. JQ237248). The sequence had 100% nucleotide identity to B. oryzae from switchgrass in Mississippi (GU222690, GU222691, GU222692, and GU222693) and New York (JF693908). Leaf spot caused by B. oryzae on switchgrass has also been described in North Dakota (1) and was seedborne in Mississippi (3). To our knowledge, this is the first report of B. oryzae from switchgrass in Tennessee. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/, 28 June 2012. (2) J. M. Krupinsky et al. Can. J. Plant Pathol. 26:371, 2004. (3) M. Tomaso-Peterson and C. J. Balbalian. Plant Dis. 94:643, 2010. (4) T. J. White et al. Pages 315-322 in: PCR Protocols: a Guide to Methods and Applications. M. A. Innis et al. (eds), Acad. Press, San Diego, 1990.

Ophiostomatoid Fungi Associated with Cryphalus Piceae in Shandong province in eastern China

2021 ◽  
Author(s):  
Runlei Chang ◽  
Xiuyu Zhang ◽  
Hongli Si ◽  
Guoyan Zhao ◽  
Xiaowen Yuan ◽  
...  
Keyword(s):  
Bark Beetles ◽  
Novel Species ◽  
Eastern China ◽  
Fungal Species ◽  
Shandong Province ◽  
Morphological Data ◽  
Ophiostomatoid Fungi ◽  
Fungal Isolates ◽  
Study Sites ◽  
Isolated Species

Abstract Cryphalus piceae parasitizes various economically important conifers. Similar to other bark beetles, C. picea vectors an assortment of fungi and nematodes. Previously, several ophiostomatoid fungi were isolated from C. piceae in Poland and Japan. In the present study, we explored the diversity of ophiostomatoid fungi associated with C. piceae infesting pines in the Shandong Province of China. We isolated ophiostomatoid fungi from both galleries and beetles collected from our study sites. These fungal isolates were identified using both molecular and morphological data. Through this study, we recovered 176 isolates of ophiostomatoid fungi representing at least seven species. Ophiostoma ips was the most frequently isolated species. Analyses of molecular and morphological data indicated four of the ophiostomatoid fungal species recovered in this study were previously undescribed. Hereby, we described these species as Ceratocystiopsis yantaiensis sp. nov., C. weihaiensis sp. nov., Graphilbum translucens sp. nov. and Sporothrix villosa sp. nov. A majority of the ophiostomatoid fungi recovered in this study were novel species. This suggests that the forests in China harbour an assortment of undescribed ophiostomatoid fungi yet to be discovered.

THYMUS SERPYLLUM – A NOVEL BIOCONTROL AGENT AGAINST LEAF SPOT PATHOGENS OF SOLANUM MELONGENA

2020 ◽  
Vol 27 (2) ◽  
pp. 469-479
Author(s):  
Shazia Shafique ◽  
Sobiya Shafique ◽  
Sonia Sahar
Keyword(s):  
Leaf Spot ◽  
Biocontrol Agent ◽  
Solanum Melongena ◽  
Management Program ◽  
Organic Extract ◽  
Exserohilum Rostratum ◽  
Pot Trials ◽  
Significant Yield ◽  
Thymus Serpyllum ◽  
Vast Range

Solanum melongena L. production is facing a lot of threats in Pakistan which are responsible for its low productivity. Like many other diseases; leaf spot is very important due to its significant yield losses. Therefore, control of this disease is obligatory to reduce the causal agent lower than commercial thresh hold level. Biological mean provides safe fungal management program. Presently, the research was under taken to ascertain the antitoxic effect of Thymus serpyllum against eggplant leaf spot pathogens i.e., Exserohilum rostratum, Cladosporium cladosporioides and Curvularia clavata. For this, 10 concentrations of methanolic plant extract (0.5% to 5%) were employed against the pathogens. Data analysis depicted that development of all the pathogens was greatly inhibited by all the concentrations while 5% concentration found to be the utmost operative in subduing the growth of all the pathogens. C. clavata was found to be the most susceptible among all the pathogens. In pot trials, protective assays proved more pronounced in controlling the disease. The work concludes that organic extract of T. serpyllum has stable compounds having ability to inhibit the damaging properties of pathogens. This fact guides towards biocontrol using such plants against the phytopathogens in a vast range. The study can be extended to isolate and purify the compounds and its production on commercial scale to manage these pathogens in vast fields.

scholarly journals First report of banana (Musa acuminate L. AAA Cavendish, cv. Formosana) leaf spot disease caused by Curvularia geniculata in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yanxiang Qi ◽  
Yanping Fu ◽  
Jun Peng ◽  
Fanyun Zeng ◽  
Yanwei Wang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Universal Primers ◽  
Leaf Spot Disease ◽  
Leaf Margin ◽  
Conidial Suspension ◽  
Tropical Fruit ◽  
First Report ◽  
Spot Disease

Banana (Musa acuminate L.) is an important tropical fruit in China. During 2019-2020, a new leaf spot disease was observed on banana (M. acuminate L. AAA Cavendish, cv. Formosana) at two orchards of Chengmai county (19°48ʹ41.79″ N, 109°58ʹ44.95″ E), Hainan province, China. In total, the disease incidence was about 5% of banana trees (6 000 trees). The leaf spots occurred sporadically and were mostly confined to the leaf margin, and the percentage of the leaf area covered by lesions was less than 1%. Symptoms on the leaves were initially reddish brown spots that gradually expanded to ovoid-shaped lesions and eventually become necrotic, dry, and gray with a yellow halo. The conidia obtained from leaf lesions were brown, erect or curved, fusiform or elliptical, 3 to 4 septa with dimensions of 13.75 to 31.39 µm × 5.91 to 13.35 µm (avg. 22.39 × 8.83 µm). The cells of both ends were small and hyaline while the middle cells were larger and darker (Zhang et al. 2010). Morphological characteristics of the conidia matched the description of Curvularia geniculata (Tracy & Earle) Boedijn. To acquire the pathogen, tissue pieces (15 mm2) of symptomatic leaves were surface disinfected in 70% ethanol (10 s) and 0.8% NaClO (2 min), rinsed in sterile water three times, and transferred to potato dextrose agar (PDA) for three days at 28°C. Grayish green fungal colonies appeared, and then turned fluffy with grey and white aerial mycelium with age. Two representative isolates (CATAS-CG01 and CATAS-CG92) of single-spore cultures were selected for molecular identification. Genomic DNA was extracted from the two isolates, the internal transcribed spacer (ITS), large subunit ribosomal DNA (LSU rDNA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II second largest subunit (RPB2) were amplified and sequenced with universal primers ITS1/ITS4, LROR/LR5, GPD1/GPD2, EF1-983F/EF1-2218R and 5F2/7cR, respectively (Huang et al. 2017; Raza et al. 2019). The sequences were deposited in GenBank (MW186196, MW186197, OK091651, OK721009 and OK491081 for CATAS-CG01; MZ734453, MZ734465, OK091652, OK721100 and OK642748 for CATAS-CG92, respectively). For phylogenetic analysis, MEGA7.0 (Kumar et al. 2016) was used to construct a Maximum Likelihood (ML) tree with 1 000 bootstrap replicates, based on a concatenation alignment of five gene sequences of the two isolates in this study as well as sequences of other Curvularia species obtained from GenBank. The cluster analysis revealed that isolates CATAS-CG01 and CATAS-CG92 were C. geniculata. Pathogenicity assays were conducted on 7-leaf-old banana seedlings. Two leaves from potted plants were stab inoculated by puncturing into 1-mm using a sterilized needle and placing 10 μl conidial suspension (2×106 conidia/ml) on the surface of wounded leaves and equal number of leaves were inoculated with sterile distilled water serving as control (three replicates). Inoculated plants were grown in the greenhouse (12 h/12 h light/dark, 28°C, 90% relative humidity). Necrotic lesions on inoculated leaves appeared seven days after inoculation, whereas control leaves remained healthy. The fungus was recovered from inoculated leaves, and its taxonomy was confirmed morphologically and molecularly, fulfilling Koch’s postulates. C. geniculata has been reported to cause leaf spot on banana in Jamaica (Meredith, 1963). To our knowledge, this is the first report of C. geniculata on banana in China.

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

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1116-1116 ◽  
Author(s):  
V. Parkunan ◽  
S. Li ◽  
E. G. Fonsah ◽  
P. Ji
Keyword(s):  
United States ◽  
Alternaria Alternata ◽  
Leaf Spot ◽  
Morphological Characteristics ◽  
The United States ◽  
Its Sequencing ◽  
Single Spore ◽  
First Report ◽  
Alternaria Leaf Spot ◽  
Leaf Spots

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

scholarly journals First Report of Leaf Spot of Sweet Basil Caused by Cercospora guatemalensis in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (10) ◽  
pp. 1580-1580
Author(s):  
J. H. Park ◽  
K. S. Han ◽  
J. Y. Kim ◽  
H. D. Shin
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Its Region ◽  
Culture Collection ◽  
Distilled Water ◽  
First Report ◽  
Sweet Basil ◽  
Organic Farm ◽  
Leaf Spots ◽  
Close Phylogenetic Relationship

Sweet basil, Ocimum basilicum L., is a fragrant herb belonging to the family Lamiaceae. Originated in India 5,000 years ago, sweet basil plays a significant role in diverse cuisines across the world, especially in Asian and Italian cooking. In October 2008, hundreds of plants showing symptoms of leaf spot with nearly 100% incidence were found in polyethylene tunnels at an organic farm in Icheon, Korea. Leaf spots were circular to subcircular, water-soaked, dark brown with grayish center, and reached 10 mm or more in diameter. Diseased leaves defoliated prematurely. The damage purportedly due to this disease has reappeared every year with confirmation of the causal agent made again in 2011. A cercosporoid fungus was consistently associated with disease symptoms. Stromata were brown, consisting of brown cells, and 10 to 40 μm in width. Conidiophores were fasciculate (n = 2 to 10), olivaceous brown, paler upwards, straight to mildly curved, not geniculate in shorter ones or one to two times geniculate in longer ones, 40 to 200 μm long, occasionally reaching up to 350 μm long, 3.5 to 6 μm wide, and two- to six-septate. Conidia were hyaline, acicular to cylindric, straight in shorter ones, flexuous to curved in longer ones, truncate to obconically truncate at the base, three- to 16-septate, and 50 to 300 × 3.5 to 4.5 μm. Morphological characteristics of the fungus were consistent with the previous reports of Cercospora guatemalensis A.S. Mull. & Chupp (1,3). Voucher specimens were housed at Korea University herbarium (KUS). An isolate from KUS-F23757 was deposited in the Korean Agricultural Culture Collection (Accession No. KACC43980). Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (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 548 bp was deposited in GenBank (Accession No. JQ995781). This showed >99% similarity with sequences of many Cercospora species, indicating their close phylogenetic relationship. Isolate of KACC43980 was used in the pathogenicity tests. Hyphal suspensions were prepared by grinding 3-week-old colonies grown on PDA with distilled water using a mortar and pestle. Five plants were inoculated with hyphal suspensions and five plants were sprayed with sterile distilled water. The plants were covered with plastic bags to maintain a relative humidity of 100% for 24 h and then transferred to a 25 ± 2°C greenhouse with a 12-h photoperiod. Typical symptoms of necrotic spots appeared on the inoculated leaves 6 days after inoculation, and were identical to the ones observed in the field. C. guatemalensis was reisolated from symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Malawi, India, China, and Japan (2,3), but not in Korea. To our knowledge, this is the first report of C. guatemalensis on sweet basil in Korea. Since farming of sweet basil has recently started on a commercial scale in Korea, the disease poses a serious threat to safe production of this herb, especially in organic farming. References: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Ithaca, NY, 1953. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology & Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , May 5, 2012. (3) J. Nishikawa et al. J. Gen. Plant Pathol. 68:46, 2002.

scholarly journals First Report of Spot Blotch Caused by Bipolaris sorokiniana on Winter Rye in Kentucky

Plant Disease ◽  
2021 ◽  
Author(s):  
Danilo Neves ◽  
Bill Bruening ◽  
Carrie A Knott ◽  
Chad Lee ◽  
Carl Bradley
Keyword(s):  
Flag Leaf ◽  
Morphological Characteristics ◽  
Bipolaris Sorokiniana ◽  
Spot Blotch ◽  
Winter Rye ◽  
Glycerol Solution ◽  
Conidial Suspension ◽  
Potential Yield ◽  
First Report ◽  
Plastic Bag

The Kentucky distilling industry ranks as one of the state’s largest industries and continues to expand. In 2017, the Kentucky distilling industry was responsible for approximately $235 million in state and local tax revenues (Coomes and Kornstein, 2019). Rye (Secale cereale L.) grains are a vital component for production of some distilled spirits. Although winter rye is produced on relatively few hectares in Kentucky currently, a recent initiative has supported expanding production to help meet the growing demand of local distilleries. University of Kentucky winter rye research field trials were visited in Caldwell and Logan Counties, KY in May 2018, and in Fayette County, KY in May 2019. Leaves were collected that had dark brown, oval to irregular-shaped lesions with definite margins and yellow halos. Symptoms were present on approximately 50% to 80% of the flag leaves, with severity ranging from 5% to 30% of the flag leaf area affected. Leaves were surface-disinfested by soaking in a 2% NaOCl solution for 1 min and rinsed twice in sterilized water and then placed in a humidity chamber (plastic bag with moist paper towels) at room temperature (approximately 24°C) to induce fungal sporulation. Seventeen single-spore isolates were obtained and stored at -80°C in 15% glycerol solution. Isolates were grown on potato dextrose agar under 12 h cycles of white light/darkness for 5 days. Colonies were gray to black. Conidia that formed were mostly straight or slightly curved, dark olivaceous brown, 3-7 septate, and 41.0-90.4 × 15.2-29.3 µm. Based on the symptoms observed on the collected leaves and these morphological characteristics similar to those described by Chang and Hwang (2000) and Manamgoda et al. (2014), the fungus was tentatively identified as Bipolaris sorokiniana (Sorokin) Shoemaker. The sequence of internal transcribed spacer regions (ITS) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were used to identify three isolates (18Bs004, 18Bs111 and 19Bs064) using primer ITS1/ITS4 (White et al. 1990) and GPD1/GPD2 (Berbee et al. 1999), respectively. The sequences were deposited in GenBank with accession numbers MT457817, MT457818 and MZ066635 for ITS sequences and MZ073644 to MZ073646 for GAPDH sequences. BLAST searches with ITS and GAPDH sequences matched 100% identity (344/344 bp and 515/515 bp for ITS and GAPDH sequences, respectively) to B. sorokiniana (GenBank accession No. MT254731 and MH844813, respectively). To prove pathogenicity, a conidial suspension (1 × 105 conidia/ml) was used to inoculate 15-day-old cultivar ‘Serafino’ winter rye plants in the greenhouse. Leaves of 8 plants were inoculated with 50 ml of the conidial suspension using a spray bottle. Plants were covered with a transparent plastic bag for 48 h, and symptoms were observed 10 days after inoculation. Leaf lesions, similar to those described above, were present on all inoculated plants, but no symptoms were observed on non-inoculated control plants. Bipolaris sorokiniana was reisolated from symptomatic leaves and the identity of the pathogen was confirmed based on the morphology previously described. To our knowledge, this is the first report of spot blotch caused by B. sorokiniana on winter rye in Kentucky, but B. sorokiniana has been reported on rye in the neighboring state of Virginia (Roane 2009). Kentucky produces approximately 150,000 and 4,000 ha of winter wheat (Triticum aestivum) and winter barley (Hordeum vulgare) annually, respectively, which are both known hosts of B. sorokiniana (Kumar et al. 2002). An isolate of B. sorokiniana from rye was reported by Ghazvini and Tekauz (2007) to be less virulent on barley differential lines. Further research is needed to better understand spot blotch distribution, susceptibility in winter rye cultivars, and potential yield and quality loss implications in winter rye production and end use. It is unknown how susceptible various winter rye cultivars grown in Kentucky are to spot blotch.

scholarly journals First Report of Leaf Spot Caused by Corynespora cassiicola on Kiwifruit (Actinidia chinensis) in China

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1586-1586 ◽  
Author(s):  
G. Q. Yuan ◽  
Y. L. Xie ◽  
D. C. Tan ◽  
Q. Q. Li ◽  
W. Lin
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Its Region ◽  
Corynespora Cassiicola ◽  
Detached Leaf Assay ◽  
Detached Leaf ◽  
Concentric Pattern ◽  
Pathogenicity Tests ◽  
Petri Dishes ◽  
Whole Plants

Kiwifruit (Actinidia) is a common fruit cultivated in many countries. Actinidia deliciosa and A. chinensis are two commercially important kiwifruit species. Over 70,000 ha are grown annually in China. In 2012, a leaf spot disease of A. chinensis was observed in several orchards in Leye County (106°34′ E, 24°47′ N), Guangxi Zhuang Autonomous Region, China. The disease mainly damaged the leaves during the fruit development stage through to the maturity stage. Initially reddish-brown small lesions appeared on the leaves; later, typical symptoms were tan to taupe lesions surrounded by purple brown margins, nearly circular to irregular, 2 to 10 × 2.2 to 15.5 mm in diameter. Some lesions exhibited a concentric pattern. The lesions eventually coalesced, causing extensive leaf necrosis and defoliation. The fungus that sporulated from lesions had the following morphological characteristics: light brown conidiophores with slightly swollen apexes, light brown conidia formed singly or in acropetal chains, straight or curved, cylindrical to oblavate, 52.9 to 240.5 μm long (avg. 138.9 μm) and 5.3 to 13.6 μm wide (avg. 8.4 μm), 5 to 12 distoseptate, with a flat, darkened, and thickened hilum. These morphological characteristics corresponded with that of Corynespora cassiicola (Berk. & Curt.) Wei (1). To isolate the pathogen of the disease, small pieces of symptomatic foliar tissues, including young lesions, typical older lesions, and atypical older lesions with concentric pattern were surface sterilized with 75% ethanol for 30 to 60 s, disinfected in 0.1% HgCl2 for 1 min followed by washing with sterile water, plated on PDA, and incubated at 28°C for 7 to 10 days. Gray to dark gray colonies and conidia of C. cassiicola were observed. To validate the identity of the fungus, the sequence of the ITS region of one of the purified strains, LYCc-1, was determined. DNA was extracted from the isolate that was grown on PDA at 28°C for 4 days, and the ITS region was amplified using the universal primer pair ITS4/ITS5 (2). The double strand consensus sequence was submitted to GenBank (KJ747095) and had 99% nt identity with published sequences of C. cassiicola in GenBank (JN853778, FJ852574, and FJ852587). Pathogenicity tests were carried out on detached leaves in petri dishes in an incubator at 28°C and on whole plants in a glasshouse at 25 ± 3°C. The isolations did not produce enough conidia in pure culture, so mycelial discs were used in pathogenicity tests. For both assays, 60-day-old healthy kiwifruit leaves were inoculated with a 5-mm mycelial disc obtained from the periphery of a 5-day-old C. cassiicola strain (LYCc-1) grown on PDA. The PDA discs were placed on the leaf surface with their mycelial surface down and secured with sterile wet cotton. Controls consisted of leaves that were inoculated with sterile PDA discs. For the detached leaf assay, the leaves were placed on filter paper reaching water saturation in petri dishes, and for the whole plant assays the inoculated leaves were kept moist with intermittent water sprays for 48 h. Four leaves of each plant were inoculated with the isolate in both assays, and experiment was repeated twice. Eight inoculated leaves of the detached leaf assay all showed the first water soaked lesions 36 h after inoculation, followed by extensive leaf rot 72 h after inoculation, and yielded abundant conidia of C. cassiicola. Six out of eight leaves inoculated on whole plants showed the first lesions 5 days after inoculation, whereas control leaves remained healthy. Only C. cassiicola was re-isolated from the lesions in both assays, fulfilling Koch's postulates. This is the first report of leaf spot caused by C. cassiicola on kiwifruit in China. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) T. J. White et al. In: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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