First Report of Phakopsora pachyrhizi on Kudzu (Pueraria montana var. lobata) in North Carolina and Increased Incidence of Soybean Rust on Soybean in 2006

Asian soybean rust, caused by Phakopsora pachyrhizi H. Sydow & Sydow, was first detected in the continental United States in soybean (Glycine max (L.) Merr.) in Louisiana on 6 November 2004 (3) and in kudzu (Pueraria montana var. lobata) in Florida during February 2005 (1). Soybean rust was first confirmed in North Carolina in commercial soybean fields in Brunswick, Columbus, and Robeson counties on 25 October 2005 (2). Subsequently, the disease was detected in soybean in 18 counties, but not in kudzu, even when it was growing adjacent to infected soybean. During 2006, soybean rust was first detected in North Carolina in soybean on 14 September 2006 from a sample from Columbus County that was submitted to the North Carolina State University Plant Disease and Insect Clinic (NCSU-PDIC). Thus, the first detection of soybean rust in North Carolina occurred almost 6 weeks earlier in 2006 than in 2005. Subsequently, in 2006, soybean rust was found in soybean in 42 counties in North Carolina through survey, sentinel plot monitoring, and samples submitted to the NCSU-PDIC. In addition, what appeared to be soybean rust was observed in two samples of kudzu collected on 3 and 6 November 2006 from Moore (35.28313°N, 79.38020°W) and Johnston (35.42742°N, 78.18154°W) counties of North Carolina. The diagnosis of P. pachyrhizi in kudzu was confirmed visually and by ELISA protocol supplied with the EnviroLogix QualiPlate kit (Portland, ME). ELISA tests for each kudzu sample were run in triplicate. PCR was also conducted on infected kudzu samples with a protocol previously reported (1). The PCR master mix that was used came from a dilution scheme based on previous PCR work completed by G. Z. Abad. A total of 24 reactions were run, including four 1-kb molecular markers, four positive controls, four negative controls, and four infected kudzu leaf tissue samples. The results of all diagnostic techniques confirmed the presence of P. pachyrhizi in diseased kudzu. To our knowledge, this is the first report of P. pachyrhizi in kudzu in North Carolina. References: (1) P. F. Harmon et al. Online publication. doi:10.1094/PHP-2005-0613-01-RS. Plant Health Progress, 2005. (2) S. R. Koenning et al. Plant Dis. 90:973, 2006. (3) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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First Report of Asian Soybean Rust Caused by Phakopsora pachyrhizi from Mexico

Plant Disease ◽

10.1094/pd-90-1260b ◽

2006 ◽

Vol 90 (9) ◽

pp. 1260-1260 ◽

Cited By ~ 5

Author(s):

A. Cárcamo Rodríguez ◽

J. Aguilar Rios ◽

J. R. Hernández

Keyword(s):

Plant Protection ◽

Soybean Rust ◽

Thin Wall ◽

Phakopsora Pachyrhizi ◽

First Report ◽

The North ◽

San Luis ◽

Asian Soybean Rust ◽

Glycine Max L ◽

Voucher Specimens

Leaves of soybean (Glycine max (L.) Merr.; Fabaceae) cv. Huasteca 400, with conspicuous chlorotic spots and associated hypophyllous cinnamon-brown sori, were collected in commercial soybean plantings in Ébano and Tamuín in the state of San Luis de Potosí, Mexico on 26 October 2005. Uredinia, Malupa-type, are mostly hypophyllous, minute, pulverulent, cinnamon-brown, scattered or in groups, subepidermal becoming erumpent, cone like, surrounded by paraphyses; paraphyses are cylindric to clavate, 25 to 50 × 6 to 14 μm, colorless to yellow brownish with wall thickened at the apex. Urediniospores are obovoid to broadly ellipsoidal, measuring 18 to 37 × 15 to 24 μm, and have a minutely echinulate thin wall, hyaline to pale yellowish brown. This morphology is typical of Phakopsora pachyrhizi Syd. & P. Syd. and P. meibomiae (Arthur) Arthur. DNA was extracted from leaves containing sori with the PureLink Plant DNA Reagent (Invitrogen, Carlsbad, CA), and the identity of P. pachyrhizi was confirmed by the polymerase chain reaction protocol (1) with Ppa1/Ppa2 primers at the National Phytosanitary Reference Center of Mexico. The morphological and molecular diagnosis and presence of P. pachyrhizi in Mexico was officially communicated by the North American Plant Protection Organization (NAPPO) on 16 February 2006. Asian soybean rust was reported for the first time in North America in 2004 (2). To our knowledge, this the first report of P. pachyrhizi in Mexico. Voucher specimens have been placed in the USDA National Fungus Collection as BPI 871130, BPI 871131, and BPI 871132. Images and a complete description of Asian soybean rust can be viewed at http://nt.arsgrin.gov/taxadescriptions/factsheets/index.cfm?thisapp=Phakopsorapachyr hizi . References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Kudzu (Pueraria montana var. lobata) in Kentucky

Plant Disease ◽

10.1094/pd-90-0834b ◽

2006 ◽

Vol 90 (6) ◽

pp. 834-834 ◽

Cited By ~ 4

Author(s):

D. E. Hershman ◽

P. R. Bachi ◽

C. L. Harmon ◽

P. F. Harmon ◽

M. E. Palm ◽

...

Keyword(s):

United States ◽

Soybean Rust ◽

Phakopsora Pachyrhizi ◽

Morphological Examination ◽

Causal Organism ◽

First Report ◽

Monitoring Effort ◽

Health Progress ◽

On Line ◽

Pueraria Montana

Phakopsora pachyrhizi, the causal organism of soybean rust, was first observed in the continental United States on 6 November 2004 (2). On 11 November 2005, as part a national soybean rust monitoring effort, 75 leaves of kudzu (Pueraria montana var. lobata) were arbitrarily collected from a patch growing in Princeton, Caldwell County, Kentucky (37.106650°N, 87.886120°W) that had been periodically scouted for the presence of the disease since May 2005. Upon microscopic examination of the nonincubated sample, a small (˜2.0 cm2) area of one leaf exhibited lesions, uredinia, and urediniospores characteristic of those reported for P. pachyrhizi (the Asian species) and P. meibomiae (the New World species) (2). No other infected leaves were observed despite repeated visits to the site and collection and observation of nearly 200 leaves. On 16 November 2005, one-half of the symptomatic tissue was sent by overnight courier to the USDA/APHIS/PPQ/NIS Laboratory, Beltsville, MD and the other half was sent to the Southern Plant Diagnostic Network Laboratory (SPDN), University of Florida, Gainesville. Both laboratories confirmed that the rust was a Phakopsora spp. on the basis of morphological examination. The preliminary polymerase chain reaction (PCR) testing conducted by the SPDN according to Harmon et al. (1) indicated the presence of P. pachyrhizi that was confirmed by the USDA/NPGBL using the validated modified real-time PCR assay described previously (2). The field diagnosis of P. pachyrhizi and preliminary PCR results were officially confirmed by USDA/APHIS on 18 November 2005. To our knowledge, this is the first report of P. pachyrhizi on kudzu or any host in Kentucky, and currently, the northernmost report of soybean rust on any host in the continental United States. References: (1) P. F. Harmon et al. On-line publication, doi:10.1094/PHP-2005-0613-O1-RS. Plant Health Progress, 2005. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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First Report of Phakopsora pachyrhizi Causing Rust on Soybean in Malawi

Plant Disease ◽

10.1094/pdis-09-14-0924-pdn ◽

2015 ◽

Vol 99 (3) ◽

pp. 420-420 ◽

Cited By ~ 7

Author(s):

H. M. Murithi ◽

F. D. Beed ◽

M. M. Soko ◽

J. S. Haudenshield ◽

G. L. Hartman

Keyword(s):

Internal Control ◽

Foliar Application ◽

Leaf Tissue ◽

Soybean Rust ◽

Phakopsora Pachyrhizi ◽

Limit Of Quantification ◽

Planting Dates ◽

Soybean Production ◽

First Report ◽

Negative Results

Soybean rust (SBR), caused by Phakopsora pachyrhizi, has become established in Africa since the first report in Uganda in 1996 (2). The urediniospores, as windborne propagules, have infested new regions of Africa, initiating SBR in many countries, including Ghana and Democratic Republic of the Congo in 2007 (4) and Tanzania in 2014 (3). No refereed reports have been published about rust in Malawi, but some people have indicated that soybean rust may have been observed as early as 2008. Typical symptoms and signs of SBR, including leaf yellowing and tan, sporulating uredinia, were observed on soybean in May 2014 during field surveys in the major soybean-growing areas of Malawi, including the central (Dowa, Mchinji, and Kasungu) and southern (Thyolo) regions in nine out of 12 sites surveyed. When microscopically examined, urediniospores were elliptical, echinulate, and hyaline to pale yellowish brown. Leaves exhibiting sporuliferous uredinia were sent by APHIS permit to the University of Illinois. To confirm the pathogen, symptomatic soybean leaf tissue of approximately 1 cm2 was excised from each of the samples, and DNA was extracted using the FastDNA Spin Kit (MP Biomedicals, Solon, OH), with further purification using the MicroElute DNA Clean-up Kit (Omega Bio-Tek, Norcross, GA). The resulting DNA was analyzed by quantitative PCR using published Taqman assays for P. pachyrhizi and P. meibomiae, with a multiplexed exogenous internal control reaction to validate negative results (1). P. pachyrhizi DNA was detected in excess of 180,000 genome equivalents/cm2 in all samples, indicating a substantial infection. P. meibomiae DNA was determined to be absent from all samples, within the limit of quantification of ~2 pg DNA/cm2. Urediniospores dislodged from three leaves and inoculated onto susceptible soybean cultivar Williams 82 produced tan lesions after 2 weeks of incubation in a detached-leaf assay. This is the first confirmed report of P. pachyrhizi causing rust on soybean in Malawi, putting at risk 14,000 ha currently under soybean production. The reports of soybean rust in Malawi and adjoining countries will alter soybean production practices and research interests. In some cases, foliar application of fungicides has increased and planting dates have been changed to avoid conditions that are most conducive for rust development. Efforts to understand the virulence and genetic diversity of the pathogen in the region are needed in order to develop and deploy resistant cultivars. References: (1) J. S. Haudenshield and G. L. Hartman. Plant Dis. 95:343, 2011. (2) R. Kawuki, et al. Afr. Crop Sci. J. 11:301, 2003. (3) H. M. Murithi et al. Plant Dis. 98:1586, 2014. (4) P. S. Ojiambo et al. Plant Dis. 91:1204, 2007.

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First Report of Soybean Rust Caused by Phakopsora pachyrhizi in North Carolina

Plant Disease ◽

10.1094/pd-90-0973a ◽

2006 ◽

Vol 90 (7) ◽

pp. 973-973 ◽

Cited By ~ 2

Author(s):

S. R. Koenning ◽

A. D. Moore ◽

T. C. Creswell ◽

G. Z. Abad ◽

M. E. Palm ◽

...

Keyword(s):

United States ◽

North Carolina ◽

South Carolina ◽

Western Hemisphere ◽

Soybean Rust ◽

Enzyme Linked Immunosorbent Assay ◽

Thin Wall ◽

Phakopsora Pachyrhizi ◽

First Report ◽

Eastern Hemisphere

Asian soybean rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the eastern hemisphere for nearly a century. More recently, it was reported from South America in 2002 and the continental United States in Louisiana in November 2004 (1,2). Subsequently, P. pachyrhizi was confirmed in Alabama, Arkansas, Georgia, Florida, Missouri, Mississippi, South Carolina, and Tennessee in 2004. Surveys conducted in North Carolina in late November 2004 failed to detect this pathogen. Symptoms of the disease were first observed on soybean (Glycine max (L.) Merr.) in North Carolina on 25 October 2005 in farmers' fields in the counties of Brunswick, Columbus, and Robeson. Typical pustules and urediniospores were readily apparent on infected leaves when viewed with a dissecting microscope. Urediniospores were obovoid to broadly ellipsoidal, hyaline to pale yellowish brown with a minutely echinulate thin wall, and measured 18 to 37 × 15 to 24 μm. This morphology is typical of soybean rust caused by P. pachyrhizi or P. meibomiae, the latter is a less aggressive species causing soybean rust in the western hemisphere (1). DNA was extracted from leaves containing sori using the Qiagen DNeasy Plant Mini kit (Valencia, CA). P. pachyrhizi was detected using a real-time polymerase chain reaction (PCR) protocol that differentiates between P. pachyrhizi and P. meibomiae in a Cepheid thermocycler (Sunnyvale, CA) with appropriate positive and negative controls. The PCR master mix was modified to include OmniMix beads (Cepheid). Field diagnosis of P. pachyrhizi was confirmed by the USDA/APHIS on 28 October 2005. Soybean rust was identified in subsequent surveys of soybean fields and leaf samples submitted by North Carolina Cooperative Extension Agents in an additional 15 counties. These samples also were assayed using a traditional PCR protocol and by the enzyme-linked immunosorbent assay protocol included in the EnviroLogix QualiPlate kit (Portland, ME) for soybean rust. Ten soybean specimens from 10 sites were confirmed positive by these methods. Disease was not found on three kudzu samples, although one kudzu sample was adjacent to a soybean field that was positive for P. pachyrhizi. Although soybean rust was eventually detected in 18 North Carolina counties in 2005, no soybean yield loss occurred since the pathogen was detected when more than 80% of the soybean crop was mature. To our knowledge, this is the first report of P. pachyrhizi in North Carolina and the northern most find on soybean in the continental United States in 2005. References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) R. W. Schneider et al. Plant Dis. 89:774 2005.

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First Report of Phakopsora pachyrhizi on Soybean Causing Rust in Tanzania

Plant Disease ◽

10.1094/pdis-06-14-0601-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1586-1586 ◽

Cited By ~ 5

Author(s):

H. M. Murithi ◽

F. D. Beed ◽

C. S. Madata ◽

J. S. Haudenshield ◽

G. L. Hartman

Keyword(s):

Internal Control ◽

Leaf Tissue ◽

Soybean Rust ◽

Western India ◽

Northeast Monsoon ◽

Phakopsora Pachyrhizi ◽

Limit Of Quantification ◽

Ongoing Research ◽

First Report

Phakopsora pachyrhizi Syd. was reported on legume hosts other than soybean in Tanzania as early as 1979 (1). Soybean rust (SBR), caused by P. pachyrhizi, was first reported on soybean in Africa in Uganda in 1996 (3), and its introduction into Africa was proposed to occur through urediniospores blowing from western India to the African east coastal areas by moist northeast monsoon winds (4). The fungus rapidly spread and was reported on soybean in South Africa in 2001, in western Cameroon in 2003, and in Ghana and the Democratic Republic of the Congo in 2007 (5). A second species causing SBR on soybean, P. meibomiae, has not been reported in Africa or elsewhere, outside of the Americas. From 2012 to 2014, symptomatic leaf samples were collected in the major soybean growing areas of the Tanzanian Southern Highlands (Iringa, Mbeya, and Ruvuma regions). Symptoms of SBR included yellowing of leaves and tan sporulating lesions. These symptoms were observed at flowering through seed maturity. From fields surveyed in 2012, 2013, and 2014, SBR was observed in 5 of 14, 7 of 11, and 14 of 31 fields, respectively. Some of the leaves sampled had up to 80% of the leaf area affected. When microscopically examined, urediniospores were elliptical, echinulate, and hyaline to pale yellowish brown. In 2014, sporuliferous uredinia were observed on leaf material collected from the Iringa and Ruvuma regions of Tanzania, and a subset of these samples was sent by APHIS permit to the University of Illinois. To confirm the pathogen, symptomatic soybean leaf tissue of approximately 1 cm2 was excised from each of the samples, and DNA was extracted using the FastDNA Spin Kit (MP Biomedicals, Solon, OH), with further purification using the MicroElute DNA Clean-up Kit (Omega Bio-Tek, Norcross, GA). The DNA was subjected to quantitative PCR using published Taqman assays for P. pachyrhizi, P. meibomiae, and a multiplexed exogenous internal control reaction to validate negative results (2). P. pachyrhizi DNA was detected in excess of 66,000 genome equivalents/cm2 in all samples, and P. meibomiae DNA was determined to be absent from all samples (limit of quantification ~2 pg DNA/cm2). Free surviving urediniospores were dislodged from 12 samples and inoculated onto susceptible soybean cultivar Williams 82, which produced sporulating SBR lesions after 2 weeks of incubation in a detached-leaf assay. Thus, Koch's postulates were completed. This is the first report of P. pachyrhizi causing rust on soybean in Tanzania. In vivo cultures have been established from most of these samples, and ongoing research includes an evaluation of the P. pachyrizi virulence on a differential set, and characterization of the genetic diversity. References: (1) D. L. Ebbels and D. J. Allen. Phytopath. Pap. 22:1-89. (2) J. S. Haudenshield and G. L. Hartman. Plant Dis. 95:343, 2011. (3) R. Kawuki et al. Afr. Crop Sci. J. 11:301, 2003. (4) C. Levy. Plant Dis. 89:669, 2005. (5) P. S. Ojiambo et al. Plant Dis. 91:1204, 2007.

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First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Pachyrhizus erosus in the United States

Plant Disease ◽

10.1094/pdis-07-10-0483 ◽

2011 ◽

Vol 95 (8) ◽

pp. 1034-1034

Author(s):

M. A. Delaney ◽

E. J. Sikora ◽

D. P. Delaney ◽

M. E. Palm ◽

J. Roscoe ◽

...

Keyword(s):

United States ◽

Ribosomal Rna ◽

Agricultural Research ◽

The United States ◽

University Teaching ◽

Soybean Rust ◽

Infected Leaf ◽

Phakopsora Pachyrhizi ◽

First Report ◽

Pachyrhizus Erosus

Soybean rust, caused by the fungus Phakopsora pachyrhizi, was detected on jicama (Pachyrhizus erosus L. Urban) for the first time in the United States in November 2009. The pathogen was observed on leaves of a single, potted jicama plant grown outdoors in a residential area and on leaves of all plants in a 12-m2 demonstration plot located at the Auburn University Teaching Garden in Auburn, AL. Symptoms on the upper leaf surfaces were isolated chlorotic areas near the leaf edges in the lower part of the canopy. The abaxial surface was first observed to exhibit brown lesions and subsequently produced volcano-shaped uredinia. These symptoms are consistent with a rust previously described on jicama in Mexico (1). Representative symptomatic plant tissue was sent to the USDA National Identification Services (Mycology) Laboratory in Beltsville, MD for diagnostic confirmation at both the Urbana, IL lab and the USDA National Plant Germplasm and Biotechnology Laboratory for DNA testing. From an infected leaf, samples of approximately 5 mm2 were excised from a microscopically observed rust lesion and an apparently noninfected area. Total DNA was purified with the FastDNA Spin Kit (MP Biomedicals, Solon, OH) followed by the E.Z.N.A. MicroElute DNA Clean-Up Kit (Omega Bio-tek, Inc, Doraville, GA) per manufacturer's instructions. Detection of P. pachyrhizi and P. meibomiae DNA was achieved by quantitative PCR using the method of Frederick et al. (2) and a DNA standard of previously prepared P. pachyrhizi spores. The observed rust pustule was found to contain P. pachyrhizi DNA in excess of 28,000 genomes, while no P. pachyrhizi DNA was observed from the asymptomatic sample. Both samples were negative for P. meibomiae. The fungal structures present were confirmed to be Phakopsora spp. DNA was extracted from sori aseptically removed from leaves with a Qiagen (Valencia, CA) DNeasy Plant Mini Kit and amplified with primers Ppa1 and NL4. The resulting partial ITS2 and 28S ribosomal RNA sequences were 100% identical to GenBank entry DQ354537 P. pachyrhizi internal transcribed spacer 2 and 28S ribosomal RNA gene, partial sequence. Sequences from jicama from Alabama were deposited in GenBank. Voucher specimens were deposited in the USDA Agricultural Research Service, National Fungus Collection (BPI). To our knowledge, this is the first report of the disease on jicama in the United States. References: (1) A. Cárcamo Rodriguez et al. Plant Dis. 90:1260, 2006. (2) R. D. Frederick et al. Phytopathology 92:217, 2002.

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First report of Coleus blumei viroid 1 in commercial Coleus blumei in the United States

Plant Disease ◽

10.1094/pdis-05-21-0917-pdn ◽

2021 ◽

Author(s):

Gardenia Orellana ◽

Alexander V Karasev

Keyword(s):

United States ◽

Leaf Tissue ◽

The United States ◽

Universal Primers ◽

Rt Pcr ◽

Universal Primer ◽

Tissue Samples ◽

First Report ◽

Specific Pcr ◽

Coleus Blumei

Coleus scutellarioides (syn. Coleus blumei) is a widely grown evergreen ornamental plant valued for its highly decorative variegated leaves. Six viroids, named Coleus blumei viroid 1 to 6 (CbVd-1 to -6) have been identified in coleus plants in many countries of the world (Nie and Singh 2017), including Canada (Smith et al. 2018). However there have been no reports of Coleus blumei viroids occurring in the U.S.A. (Nie and Singh 2017). In April 2021, leaf tissue samples from 27 cultivars of C. blumei, one plant of each, were submitted to the University of Idaho laboratory from a commercial nursery located in Oregon to screen for the presence of viroids. The sampled plants were selected randomly and no symptoms were apparent in any of the samples. Total nucleic acids were extracted from each sample (Dellaporta et al. 1983) and used in reverse-transcription (RT)-PCR tests (Jiang et al. 2011) for the CbVd-1 and CbVd-5 with the universal primer pair CbVds-P1/P2, which amplifies the complete genome of all members in the genus Coleviroid (Jiang et al. 2011), and two additional primer pairs, CbVd1-F1/R1 and CbVd5-F1/R1, specific for CbVd-1 and CbVd-5, respectively (Smith et al. 2018). Five C. blumei plants (cvs Fire Mountain, Lovebird, Smokey Rose, Marrakesh, and Nutmeg) were positive for a coleviroid based on the observation of the single 250-nt band in the RT-PCR test with CbVds-P1/P2 primers. Two of these CbVd-1 positive plants (cvs Lovebird and Nutmeg) were also positive for CbVd-1 based on the presence of a single 150-nt band in the RT-PCR assay with CbVd1-F1/R1 primers. One plant (cv Jigsaw) was positive for CbVd-1, i.e. showing the 150-nt band in RT-PCR with CbVd1-F1/R1 primers, but did not show the ca. 250-bp band in RT-PCR with primers CbVds-P1/P2. None of the tested plants were positive for CbVd-5, either with the specific, or universal primers. All coleviroid- and CbVd-1-specific PCR products were sequenced directly using the Sanger methodology, and revealed whole genomes for five isolates of CbVd-1 from Oregon, U.S.A. The genomes of the five CbVd-1 isolates displayed 96.9-100% identity among each other and 96.0-100% identity to the CbVd-1 sequences available in GenBank. Because the sequences from cvs Lovebird, Marrakesh, and Nutmeg, were found 100% identical, one sequence was deposited in GenBank (MZ326145). Two other sequences, from cvs Fire Mountain and Smokey Rose, were deposited in the GenBank under accession numbers MZ326144 and MZ326146, respectively. To the best of our knowledge, this is the first report of CbVd-1 in the United States.

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First Report of Phakopsora pachyrhizi Telia on Kudzu in the United States

Plant Disease ◽

10.1094/pd-90-0380c ◽

2006 ◽

Vol 90 (3) ◽

pp. 380-380 ◽

Cited By ~ 10

Author(s):

C. L. Harmon ◽

P. F. Harmon ◽

T. A. Mueller ◽

J. J. Marois ◽

G. L. Hartman

Keyword(s):

United States ◽

South Carolina ◽

Leaf Surface ◽

The United States ◽

Visual Observation ◽

Soybean Rust ◽

Hypodermic Needle ◽

Phakopsora Pachyrhizi ◽

First Report ◽

Telial Stage

Soybean rust caused by Phakopsora pachyrhizi H. Sydow & Sydow was first reported in the continental United States during 2004 (2). By 10 November 2005, the disease was confirmed in eight southern states (Florida, Georgia, Alabama, Mississippi, South Carolina, North Carolina, Louisiana, and Texas). Diagnoses have been based on visual observation of uredinia and urediniospores of the pathogen followed by polymerase chain reaction confirmation. On 10 November 2005, uredinia and telia were identified on leaves of kudzu (Pueraria lobata) in central Florida. Telia first were noted as dark brown-to-black flecks on the abaxial leaf surface intermingled with abundant tan-to-light brown uredinia. Of 200 leaves examined, 143 (72%) had telia. The number of telia ranged from a few (1/cm2) that were scattered to many (73/cm2). Telia were approximately the same diameter as uredinia, but were appressed to the leaf surface and pigmented. Twenty telia were excised from host tissue with the aid of a dissecting microscope and a 20 gauge hypodermic needle. Telia averaged 89 × 100 μm (n = 20, σ = 17 and 16 μm, respectively). Four telia were crushed and five teliospores from each averaged 4.3 × 8.3 μm (n = 20, σ = 0.5 and 0.9 μm, respectively). Pale yellowish brown-to-hyaline teliospores were similar in color to urediniospores. Observations matched descriptions by Ono et al. (1). To our knowledge, this is the first report of the telial stage of P. pachyrhizi in the United States. References: (1) Y. Ono et al. Mycol. Res. 96:825, 1992. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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First report of Grapevine yellow speckle viroid 1 infecting grapevine (Vitis vinifera L.) in Canada

Plant Disease ◽

10.1094/pdis-04-21-0863-pdn ◽

2021 ◽

Author(s):

Dong Xu ◽

Charith Raj Adkar-Purushothama ◽

Pierre Lemoyne ◽

Jean Pierre Perreault ◽

Mamadou Fall

Keyword(s):

Rna Extraction ◽

Leaf Tissue ◽

Positive Sequence ◽

Wine Grape ◽

Library Preparation ◽

Rt Pcr ◽

Tissue Samples ◽

First Report ◽

Stunt Viroid ◽

Hop Stunt Viroid

Quebec is the third largest wine grape producer in Canada in acreage, tonnage, and wine grape sales (Carisse et al. 2017; Ben Moussa et al. 2019). To evaluate the diversity of viruses infecting grapevine in Quebec, a total of 77 leaf tissue samples (cv. Vidal) were collected from July to October in 2020 in three different vineyards located in Frelighsburg, Hemmingford and Saint-Jacques-le-Mineur in Quebec, Canada. Double-stranded RNA was extracted from each sample and used for cDNA library preparation with the Nextera XT DNA Library Preparation Kit (Illumina) as described previously (Kesanakurti et al. 2016). High-throughput sequencing (HTS, 2x300 bp) was conducted on dual-indexed libraries in a v3 flow cell using the Illumina MiSeq platform (Adkar-Purushothama et al. 2020). The obtained raw FASTQ data was de-multiplexed into 154 separate sequence files, and the adapters and barcode sequences were trimmed. The quality of the sequences was verified using Trimmomatic V.0.32 and the “clean” sequences were analyzed using Virtool and VirFind virus detection pipelines described elsewhere (Ho and Tzanetakis 2014; Rott et al. 2017) to screen for all possible viruses in the databases. Over 100,000 reads per sample were obtained with a percentage of mapped viral reads ranging from 1.47 to 19.43% of total number of reads. Out of 77 samples, 16 revealed the sequence of grapevine yellow speckle viroid 1 (GYSVd-1), for which the length coverage ranged from 98.5 to 99.1%; the depth ranged from 2X to 856X. The GYSVd-1 positive sequence files were subjected to whole genome assembly on CLC genomics Workbench v20.0.4 with the isolate SY-BR from Brazil (KU880715) used as reference. Seven complete genomes of GYSVd-1 of 366-368 nucleotides (nt) in size were deposited (GenBank Acc. MW732682 to MW732688). BLASTN analysis of the sequences showed 98-100% nt identities with isolate SY-BR. Other viruses and viroids such as Grapevine fleck virus, Grapevine rupestris stem pitting-associated virus, Grapevine rupestris vein feathering virus and Hop stunt viroid were also detected. To confirm GYSVd-1 presence in Quebec vineyards, seven of the 16 HTS-positive grapevine leaf tissue samples were subjected to total RNA extraction, followed by RT-PCR assay as before (Adkar-Purushothama et al. 2015; Sahana et al. 2013); all were positive by RT-PCR. The PCR products were directly Sanger-sequenced, and they showed 100% nt identity to the HTS derived sequences. Three of the seven GYSVd-1 positive grapevines exhibited yellow leaf spots and flecks and tiny yellow leaves, but their mixed infection status makes definitive symptoms association difficult to determine. Previously, Hop stunt viroid was reported from grapevines in Canada (Xiao et al. 2019; Fall et al. 2020) but to the best of our knowledge, this is the first report of GYSVd-1 infecting grapevines in Canada, specifically in the province of Quebec. Further research is required to assess the GYSVd-1 related yield loss. Monitoring and testing for GYSVd-1 infection is necessary to prevent propagation of infected materials, spread, and potential negative impact for the Canadian grapevine industry.

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First Report of Phoma terrestris Causing Red Root Rot on Sweet Corn (Zea mays) in North Carolina

Plant Disease ◽

10.1094/pdis-91-8-1054c ◽

2007 ◽

Vol 91 (8) ◽

pp. 1054-1054 ◽

Cited By ~ 5

Author(s):

S. R. Koenning ◽

J. W. Frye ◽

J. K. Pataky ◽

M. Gibbs ◽

D. Cotton

Keyword(s):

North Carolina ◽

Root Rot ◽

Sweet Corn ◽

Adventitious Shoot ◽

Fresh Market ◽

First Report ◽

The North ◽

Field Corn ◽

Foliar Symptoms ◽

Corn Plants

Red root rot, caused by Phoma terrestris E. M. Hansen, caused premature senescence and yield reductions to fresh-market sweet corn in Hyde County, North Carolina in July 2006. Foliar symptoms developed over a period of 5 to 8 days approximately 1 to 2 weeks after anthesis and included desiccation of leaves and poor development of ears. By 3 weeks after pollination, when the sweet corn was harvested, crowns and the first aboveground internode of affected plants were rotted and reddish colored, but roots appeared normal. The root mass of affected plants tended to be greater than that of unaffected plants. Incidence of symptomatic plants was greater than 30% in some fields and was lower on crops planted and harvested early. Symptomatic and asymptomatic plants were adjacent in affected fields. Diseased plants were more common in fields of sweet corn that followed soybean (Glycine max) or a double-crop of onions (Allium cepa) than in fields that followed corn. Incidence of symptomatic plants also differed among adjacent plantings of different sweet corn hybrids. Hybrids ‘173A’, ‘182A’, ‘378a’, and ‘XTH1178’ had a high incidence of symptomatic plants and ‘372A’, ‘278A’, ‘8101’, and ‘8102’ were less affected. Samples of symptomatic plants of the hybrid ‘182A’ were examined at the North Carolina Plant Disease and Insect Clinic during August. Olivaceous black pycnidia with long setae around the ostioles were imbedded in the stalk near the first node aboveground. Numerous conidia (1.8 to 2.3 × 4.5 to 5.5 μm) were released in cirri from pycnidia. When cultured on potato dextrose agar (PDA), the fungus produced a red pigment and intercalary and terminal chlamydospores. Pathogenicity was demonstrated in the greenhouse by transplanting corn seedlings or direct-seeding corn into pots of soil infested with plates of PDA containing chlamydospores and hyphae. A suspension of chlamydospores and hyphae also was injected into the stems of plants 28 days after transplanting. Five replicates of the pathogenicity experiments were repeated twice with noninoculated controls. After 8 weeks, P. terrestris was recovered from the roots of all inoculated plants. Soil inoculation resulted in necrotic root tissue in approximately 25% of inoculated plants. Approximately 90% of inoculated plants had discolored crowns that resembled symptoms from field infected plants. Stem inoculations resulted in necrosis extending 2 to 5 cm from the point of injection and resulted in shoot death of 40% of inoculated plants that resulted in the development of an adventitious shoot. Red root rot was prevalent on field corn in the Delmarva Peninsula throughout the late 1980s and 1990s (1). To our knowledge, this is the first report of this disease causing damage to sweet corn in North Carolina. Foliar symptoms and discoloration of crowns of diseased sweet corn plants were similar to previously described symptoms of red root rot on field corn (2), however, roots of affected sweet corn plants were not substantially rotted and did not have a symptomatic reddish pink or dark carmine color, presumably because sweet corn is harvested prior to the development of root symptoms. References: (1) K. W. Campbell et al. Plant Dis. 75:1186, 1991. (2) D. G. White, ed. Compendium of Corn Diseases. The American Phytopathological Society, St Paul, MN, 1999.

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