scholarly journals First Report of Leaf and Fruit Spot of Citrus reticulata Blanco cv. Nian Ju Caused by Colletotrichum truncatum in China

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 422-422 ◽  
Author(s):  
B. P. Cheng ◽  
Y. H. Huang ◽  
A. T. Peng ◽  
J. F. Ling ◽  
X. B. Song ◽  
...  
Keyword(s):  
Cultural Practice ◽  
Phaseolus Lunatus ◽  
Citrus Reticulata ◽  
Sterile Water ◽  
Colletotrichum Truncatum ◽  
First Report ◽  
Potted Plants ◽  
Citrus Reticulata Blanco ◽  
Fruit Spot ◽  
Citrus Leaves

In the spring of 2011, leaf and fruit spot symptoms were observed in three orchards planted with Citrus reticulata Blanco cv. Nian Ju in Longmen City, Guangdong Province. The incidence of fruit and leaf spot ranged from of 5 to 25% across all three orchards. Similar symptoms were not observed on the fruit of C. reticulata cv. Shiyue Ju planted at the same orchards. Lesions on the diseased leaves and fruit first emerged on the lower portions of the trees and were initially small, circular, and diffuse in distribution over the leaf surface. Within 2 weeks, the small circular spots on the leaves and fruit enlarged to brown sunken necrotic lesions ranging from 5 to 30 mm in diameter. To isolate the causal organism, symptomatic leaves and fruit peels (from different trees) adjacent to the lesions as well as the lesions themselves were surface-disinfested with 1% sodium hypochlorite for 1 min and rinsed three times with sterile water. The tissues were then plated on potato dextrose agar (PDA) under alternating light and dark conditions at 28°C for 4 days. Sixteen fungal isolates with nearly identical fungal colonies were recovered from all samples. After 7 days of incubation, isolates with grayish white to dark gray mycelium and salmon pink conidia masses were observed. The conidia were hyaline, smooth-walled, aseptate, one-celled, and falcate, with oil droplets in the cytoplasm. The conidia were 19.7 to 22.5 (mean = 21.5) × 2.8 to 3.9 (mean = 3.4) μm. The fungal colonies also produced acervuli, setae, and sclerotia in the culture. The cultural and morphological characteristics of these isolates were consistent with the description of Colletotrichum truncatum (2). The ACT, TUB2, CHS I, GAPDH, and ITS regions of four representative isolates (GenBank Accession Nos. KF591214, KF591213, KF591211, KF591212, and KF011205) were sequenced and identical to those of the type specimen of C. truncatum CBS 151.35. To determine pathogenicity, leaves of three 3-year-old potted plants and ten 8-month-old fruit of C. reticulata Blanco cv. Nian Ju were each wound-inoculated with 20 μl of a suspension of conidia (1 × 105 conidia/ml). Leaves of an additional two potted plants and 10 similarly-aged fruit were wound-inoculated with 20 μl of sterile water as control. The citrus plants and fruit were then maintained at 90% relative humidity at 28°C with a 12-h photoperiod. Symptoms identical to those observed in the orchards in Longmen City developed on all of the inoculated citrus leaves and fruit after 14 days. The controls remained healthy throughout this period. The inoculation experiment was performed a second time with identical results. Isolates of C. truncatum identical to that of the isolate used for inoculation were obtained from all the inoculated symptomatic citrus leaves and fruit. C. truncatum has a broad host range and is known to be pathogenic on several crops including Medicago sativa L., Phaseolus lunatus, and Arachis hypogea (1,2,3,4). To our knowledge, this is the first report of leaf and fruit rot of C. reticulata Blanco cv. Nian Ju caused by C. truncatum in China. The golden-yellow fruit of C. reticulata Blanco cv. Nian Ju are commonly displayed during the Spring Festival of the Chinese New Year, and future epidemics of fruit spot may affect sustainability of this important cultural practice. References: (1) P. A. Backman et al. Plant Dis. 66:1032, 1982. (2) U. Damm et al. Fungal Divers. 39:45, 2009. (3) C. Eken and E. Demirci. Plant Dis. 84:100, 2000. (4) F. Huang et al. Fungal Divers. 61:61, 2013.

scholarly journals First Report of Colletotrichum siamense Causing Leaf Drop and Fruit Spot of Citrus reticulata Blanco cv. Shiyue Ju in China

Plant Disease ◽  
2013 ◽  
Vol 97 (11) ◽  
pp. 1508-1508 ◽  
Author(s):  
B. P. Cheng ◽  
Y. H. Huang ◽  
X. B. Song ◽  
A. T. Peng ◽  
J. F. Ling ◽  
...  
Keyword(s):  
Potato Dextrose Agar ◽  
Citrus Reticulata ◽  
Sterile Water ◽  
Yield Losses ◽  
First Report ◽  
Citrus Reticulata Blanco ◽  
Fruit Spot ◽  
Wide Range ◽  
Colletotrichum Siamense ◽  
Leaf Drop

Citrus reticulata Blanco cv. Shiyue Ju, which produces one of China's most popular tropical fruits, is widely planted throughout southern China. In 2008, a new citrus disease was found in Zhaoqing City in Guangdong Province on about 20,000 ha. Yield losses averaged 15% on a wide range of different aged trees of C. reticulata cv. Shiyue Ju. No yield losses were observed on C. reticulata cv. Gong gan. Symptoms first appeared on young leaves as leaf lesions, which were reddish-brown, elliptical, and 2 to 5 mm in diameter. After several weeks, 20 to 70% of leaves dropped and 10 to 50% of fruits on the trees showed brown spots (5 to 40 mm in diameter). Leaves and fruit peels adjacent to and including lesions from different trees were surface disinfested with 1% sodium hypochlorite for 1 min and rinsed three times in sterile water. Then the tissues were plated on potato dextrose agar (PDA) in alternating light and dark at 28°C for 3 days. Twenty-three similar isolates of a fast-growing fungus were recovered from all samples. For identification, single-spore cultures were grown on potato dextrose agar (PDA) at 28°C. Initially, the colonies were white, but after 5 days, they became pale gray with concentric zones and greenish black beneath. No setae, acervuli, or ascocarp were observed in the PDA culture. Conidia formed in pink conidial masses, were hyaline, fusiform, straight, obtuse at the ends, sometimes slightly curved, and 14 to 20 × 4.5 to 6 μm (x¯ = 16.2 ± 1.5 × 4.9 ± 0.5, n = 100). The cultural and morphological characteristics of these isolates matched the description of Colletotrichum siamense (3), but not that of C. gloeosporioides or C. acutatum, which cause anthracnose on citrus plants (1,2). The actin, β-tubulin, CHS I, CAL, GPDH, and ITS regions of four representative isolates (GenBank KC524462, KC524463, KC524464, KC524465, KC524466, and KC524467) were identical and with almost 100% identity to those of the type specimen of C. hymenocallidis isolate CSSN3 (C. hymenocallidis is synonymous with C. siamense) (4), except for two inconsistent nucleotide bases in the GPDH gene. Four potted plants of C. reticulata cv. Shiyue Ju were used for pathogenicity tests. On each plant, 10 randomly selected leaves and four 6-month-old fruits were wound-inoculated with 20 μl of sterile water or conidial suspensions (1 × 105 conidia per ml). Plants were then maintained at 90% relative humidity with a 12-h photoperiod at 28°C. Symptoms resembling those in the field were observed on three inoculated plants after 14 days. In another similar experiment without wounding, three of 20 inoculated plants exhibited the symptoms after 14 days. Controls remained healthy throughout this period. The tests were performed three times. C. siamense was reisolated from all diseased inoculated plants, and the culture and fungus characteristics were the same as the original isolate. Thus, C. siamense was determined to be the pathogen causing leaf drop and fruit spot on C. reticulata cv. Shiyue Ju. To our knowledge, this is the first report of leaf drop and fruit spot on C. reticulata cv. Shiyue Ju caused by C. siamense. References: (1) H. Benyahia et al. Plant Pathol. 52:798, 2003. (2) N. A. Peres et al. Plant Dis. 89:784, 2005. (3) H. Prihastuti, et al. Fungal Diversity 39:89, 2009. (4) B. Weir et al. Stud Mycol. 73:115, 2012.

First report of post-harvest Fusarium rot caused by Fusarium oxysporum on Citrus reticulata Blanco cv. ‘Kinnow’ in Pakistan

2020 ◽  
Vol 102 (3) ◽  
pp. 945-946
Author(s):  
Anam Moosa ◽  
Ayaz Farzand ◽  
Shahbaz Talib Sahi ◽  
Sajid Aleem Khan ◽  
Muhammad Fahim Abbas ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Citrus Reticulata ◽  
First Report ◽  
Post Harvest ◽  
Citrus Reticulata Blanco ◽  
Fusarium Rot

First report of Alternaria alternata causing post-harvest brown spot of Citrus reticulata Blanco cv. ‘Kinnow’ in Pakistan

2021 ◽  
Author(s):  
Anam Moosa ◽  
Ayaz Farzand ◽  
Shahbaz Talib Sahi ◽  
Sajid Aleem Khan ◽  
Muhammad Naveed Aslam ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Brown Spot ◽  
Citrus Reticulata ◽  
First Report ◽  
Post Harvest ◽  
Citrus Reticulata Blanco

scholarly journals First Report of Leaf Spot on Tibouchina semidecandra Caused by Beltrania rhombica in China

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1380-1380 ◽  
Author(s):  
Z. R. Shi ◽  
M. M. Xiang ◽  
Y. X. Zhang ◽  
J. H. Huang
Keyword(s):  
Leaf Spot ◽  
Its Region ◽  
Control Measures ◽  
Control Treatment ◽  
Sterile Water ◽  
Single Spore ◽  
First Report ◽  
Potted Plants ◽  
Detached Leaves

Tibouchina semidecandra Cogn. is a popular ornamental plant in tropical and subtropical areas (1). In August 2011, a leaf spot was observed on approximately 70% of 5,000 potted plants of T. semidecandra in a nursery in Zhongshan, Guangdong Province, China. Each leaf spot was round with a brown center surrounded by a reddish brown border, and ranged from 8 to 10 mm in diameter. A fungus was isolated consistently from the lesions by surface-sterilizing symptomatic leaf sections (each 3 cm2) with 75% alcohol for 8 s, washing the sections with sterile water, soaking the sections in 3% NaOCl for 15 s, rinsing the sections with sterile water three times, and then placing the sections on potato dextrose agar (PDA) at 28°C. Each of three single-spore isolates on PDA produced gray, floccose colonies that reached 70 mm in diameter after 5 days at 28°C. Setae were dark brown, straight, erect, distantly and inconspicuously septate, and 125 to 193 × 3.0 to 4.5 μm. Conidiophores were light brown, cylindrical, simple or sometimes branched at the base, and 105 to 202 × 3 to 5 μm. Separating cells were hyaline, oval, and 12 to 13 × 4 to 5 μm. Conidia were unequally biconic, unicellular, dark brown with a pale brown or subhyaline band just above the widest part, and 26 to 31 × 8.5 to 12 μm (mean 27.3 × 10.6 μm) with a conspicuous appendage at the apex that was 6 to 14 × 1 to 1.8 μm. These characteristics were consistent with the description of Beltrania rhombica Penz. (3). The internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) of one isolate (GenBank Accession No. JN853777) was amplified using primers ITS4 and ITS5 (4) and sequenced. A BLAST search in GenBank revealed 97% similarity to the ITS sequence of an isolate of B. rhombica (GU797390.1). To confirm pathogenicity of the isolate, ten detached leaves from 3-month-old plants of T. semidecandra ‘Purple Glorybush’ were inoculated in vitro with 5-mm diameter, colonized mycelial plugs from the periphery of 5-day-old cultures of the isolated fungus. The agar plugs were put on the leaf surface and secured with sterile, moist cotton. Sterile PDA plugs were similarly used as the control treatment on ten detached leaves. Leaves were placed in petri dishes and incubated in a growth chamber with 12 h of light/day at 28°C. Necrotic lesions appeared on leaves after 2 to 3 days of incubation, whereas control leaves inoculated with sterile PDA plugs remained asymptomatic. B. rhombica was consistently reisolated from the lesions using the same method described above, but was not reisolated from the control leaves. Although there are approximately 77 reported hosts of B. rhombica (2), to our knowledge, this is the first report of B. rhombica causing a leaf spot on T. semidecandra. Because the disease caused foliar damage and reduced the ornamental value of the nursery plants, control measures may need to be implemented for this species in nurseries. References: (1) M. Faravani and B. H. Bakar. J. Food Agric. Env. Pap. 5:234, 2007. (4) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 30 Mar. 2012. (2) K. A. Pirozyski and S. D. Patil. Can. J. Bot. Pap. 48:567, 1970. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Anthracnose on Peach Fruit Caused by Colletotrichum truncatum in South Carolina

Plant Disease ◽  
2014 ◽  
Vol 98 (8) ◽  
pp. 1154-1154 ◽  
Author(s):  
A. Grabke ◽  
M. Williamson ◽  
G. W. Henderson ◽  
G. Schnabel
Keyword(s):  
South Carolina ◽  
Causal Agent ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Colletotrichum Truncatum ◽  
Peach Fruit ◽  
First Report ◽  
Anthracnose Disease ◽  
Control Fruit

In July 2013, two diseased peach fruit (Prunus persica (L.) Stokes) of the cv. Sweet Dream were collected from a commercial orchard in Ridge Springs, South Carolina. Affected peaches were at or near maturity and symptoms resembled anthracnose disease caused by Colletotrichum spp. with circular sunken tan to brown lesions that were firm in touch, and had wrinkled concentric rings. The center of the lesion was covered with black acervuli containing setae. To isolate the causal agent, the two symptomatic fruit were surface-sterilized in 10% bleach for 2 min and rinsed with sterile distilled water. Lesions were cut in half, and necrotic tissue from the inside of the fruit was placed on acidified potato dextrose agar (APDA). Flat colonies covered with olive-gray to iron-gray acervuli developed on APDA incubated at 22°C with a 12-h cycle of fluorescent light and darkness. Morphology of acervuli, setae (avg. 90 to 160 μm), conidiophores (up to 90 um long), and conidia (avg. 22 × 3.8 μm) of single spore isolates were consistent with descriptions of Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore (3), a causal agent of anthracnose disease. Genomic DNA was extracted from isolate Ct_RR13_1 using the MasterPure Yeast DNA Purification Kit (Epicentre, Madison, WI). The ribosomal ITS1-5.8S-ITS2 region and a partial sequence of the actin gene were amplified with primer pair ITS1 and ITS4 (4), and primer pair ACT-512F and ACT-783A (2), respectively. A multilocus sequence identification in Q-bank Fungi revealed a 100% similarity with C. truncatum (1). The C. truncatum sequences from the peach isolate were submitted to GenBank (accessions KF906258 and KF906259). Pathogenicity of isolate Ct_RR13_1 was confirmed by inoculating five mature but still firm peach fruits with a conidial suspension of C. truncatum. Peaches were washed with soap and water, surface-disinfected for 2 min with 10% bleach, rinsed with sterile distilled water, and air dried. Dried fruit were stabbed at three equidistant points, each about 2 cm apart, to a depth of 9.5 mm using a sterile 26G3/8 beveled needle (Becton Dickinson & Co., Rutherford, NJ). For inoculation, a 30-μl droplet of conidia suspension prepared in distilled, sterile water (1 to 2 × 104 spores/ml) was placed on each wound; control fruit received sterile water without conidia. Fruit were incubated at 22°C for 2 days at 100% humidity and another 12 days at 70% humidity. Inoculated fruit developed anthracnose symptoms with sporulating areas as described above and the fungus was re-isolated. All control fruit remained healthy. C. truncatum has a wide host range, including legumes and solanaceous plants of the tropics, and is especially common in the Fabaceae family. Its occurrence in a commercial peach orchard is worrisome because control measures may need to be developed that are different from those developed for endemic species, i.e. C. acutatum and C. gloeoporioides, due to differences in disease cycle or fungicide sensitivity. To our knowledge, this is the first report of C. truncatum causing anthracnose on a member of the genus Prunus. References: (1) P. Bonants et al. EPPO Bull. 43:211, 2013. (2) I. Carbone et al. Mycologia 91:553, 1999. (3) U. Damm et al. Fungal Divers. 39:45, 2009. (4) T. J. White et al. Pages 315-322 in: PCR Protocols: A Guide to Methods and Application. Academic Press, NY, 1993.

scholarly journals First Report of Foliar Blight Caused by Phytophthora capsici on Citrus reticulata Blanco cv. Nian Ju in Guangdong, China

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 845-845
Author(s):  
B. P. Cheng ◽  
L. M. Lu ◽  
A. T. Peng ◽  
X. B. Song ◽  
J. F. Ling ◽  
...  
Keyword(s):  
Phytophthora Capsici ◽  
Morphological Characteristics ◽  
Broad Host Range ◽  
Pathogenicity Test ◽  
Citrus Reticulata ◽  
Causal Organism ◽  
First Report ◽  
Citrus Reticulata Blanco ◽  
Foliar Blight ◽  
Initial Symptoms

Citrus reticulata Blanco cv. Nian Ju, an important ornamental plant, is traditionally displayed during the Chinese Spring Festival because its golden fruits are a symbol of auspiciousness. In the spring of 2012, foliar blight was observed on 10 to 30% of the Nian Ju plants at four nurseries in Yangjiang, Guangdong Province, China. Initial symptoms appeared as brown to black foliar lesions, followed by expansion of spots into blight. Some young branches also had necrosis. During frequent rainfall and prolonged wet periods at 22°C to 30°C, white and dense mycelia and sporangia were observed on the infected seedlings. To isolate the causal organism, leaves and stems were cut into sections. Each section included some partial lesion and adjacent asymptomatic tissues. They were surface-disinfested in 1% sodium hypochlorite for 60 s, rinsed three times with sterile water, and placed on V8 juice agar (V8A) at 25°C. After 3 days, 10 isolates were obtained and purified by single-zoospore method. These isolates were identified to species level by sequencing the rRNA internal transcribed spacer (ITS) region. Four representative isolates had an identical ITS sequence (GenBank Accession No. KF750568), which had 99% homology with Phytophthora capsici sequences in GenBank. In addition, all recovered isolates were identical in morphological characteristics. They produced caducous, papillate, and ovoid to ellipsoid sporangia (Length × width = 46.2 ± 7.7 × 23.6 ± 11.3 μm), often with a tapered base. The average length of pedicels was 33.3 ± 4.5 μm. All isolates are A2 mating type. They produced gametangia when paired with an A1 tester of P. capsici isolated from pepper on V8A. Plerotic oospores were 25.3 ± 2.1 μm in diameter. Amphigynous antheridia were 13.6 ± 2.8 μm long and 11.2 ± 0.9 μm wide. Oogonia were 27.4 ± 3.2 μm in diameter. To determine the pathogenicity, three 3-year-old potted C. reticulata cv. Nian Ju plants were sprayed with 20 ml of zoospore suspension from one representative isolate at 105 per ml. Two control plants were sprayed with 20 ml distilled water. All plants were then maintained at 90% relative humidity at 25°C with a 12-h photoperiod. Symptoms similar to those observed in the nurseries developed on all inoculated plants but not on any control plants after 10 days. The pathogenicity test was repeated once and similar results were obtained. P. capsici was recovered from all inoculated plants and resultant isolates had identical morphology to that of the isolates used for inoculation. P. capsici has a relatively broad host range including pumpkins, cucumbers, peppers, beans, squashes, and spinach (1,2). To our knowledge, this is the first report of foliar blight of C. reticulata cv. Nian Ju caused by P. capsici. This study indicates that P. capsici is potentially an important pathogen of C. reticulata cv. Nian Ju plants and further investigations into its epidemiology and development of site-specific integrated management programs for this new disease are warranted. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN, 1996. (2) D. Tian and M. Babadoost. Plant Dis. 88:485. 2004.

scholarly journals Identification of Lasiodiplodia pseudotheobromae Causing Fruit Rot of Citrus in China

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Jianghua Chen ◽  
Zihang Zhu ◽  
Yanping Fu ◽  
Jiasen Cheng ◽  
Jiatao Xie ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Citrus Fruit ◽  
Economic Loss ◽  
Fruit Rot ◽  
Post Inoculation ◽  
Citrus Reticulata ◽  
Postharvest Diseases ◽  
Citrus Reticulata Blanco

Considering the huge economic loss caused by postharvest diseases, the identification and prevention of citrus postharvest diseases is vital to the citrus industry. In 2018, 16 decayed citrus fruit from four citrus varieties—Satsuma mandarin (Citrus unshiu), Ponkan (Citrus reticulata Blanco cv. Ponkan), Nanfeng mandarin (Citrus reticulata cv. nanfengmiju), and Sugar orange (Citrus reticulata Blanco)—showing soft rot and sogginess on their surfaces and covered with white mycelia were collected from storage rooms in seven provinces. The pathogens were isolated and the pathogenicity of the isolates was tested. The fungal strains were identified as Lasiodiplodia pseudotheobromae based on their morphological characteristics and phylogenetic analyses using the internal transcribed spacer regions (ITS), translation elongation factor 1-α gene (TEF), and beta-tubulin (TUB) gene sequences. The strains could infect wounded citrus fruit and cause decay within two days post inoculation, but could not infect unwounded fruit. To our knowledge, this is the first report of citrus fruit decay caused by L. pseudotheobromae in China.

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.

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