Hosts of Phakopsora pachyrhizi Identified in Field Evaluations in Florida

2008 ◽  
Vol 9 (1) ◽  
pp. 6 ◽  
Author(s):  
T. L. Slaminko ◽  
M. R. Miles ◽  
J. J. Marois ◽  
D. L. Wright ◽  
G. L. Hartman
Keyword(s):  
Field Trials ◽  
Soybean Rust ◽  
Broad Host Range ◽  
Pueraria Lobata ◽  
Phakopsora Pachyrhizi ◽  
Legume Species ◽  
Causal Organism ◽  
The Usa ◽  
New Hosts ◽  
Phaseolus Species

Phakopsora pachyrhizi, the causal organism of soybean rust, was first found on Glycine max in the continental United States in 2004, and subsequently on Pueraria lobata, Desmodium tortuosum, three Phaseolus species, and Erythrina herbacea in the field. The pathogen has been reported to occur on over 150 legume species worldwide, and it is likely to infect native and introduced legume species in the USA. The objective of this study was to determine if USA-native or -naturalized legume species could become infected with P. pachyrhizi in field conditions. A total of 80 accessions representing 52 species in 29 genera were infected in the field trials. Crotalaria retusa, Lathyrus latifolius, Phaseolus angustissimus, P. polystachios, and Robinia hispida are new hosts. This is the first report showing the broad host range of P. pachyrhizi based on field infections in the USA. Some of these hosts grow in the southern USA, and could, like kudzu, overwinter P. pachyrhizi. Accepted for publication 18 August 2008. Published 3 November 2008.

scholarly journals New Legume Hosts of Phakopsora pachyrhizi Based on Greenhouse Evaluations

Plant Disease ◽  
2008 ◽  
Vol 92 (5) ◽  
pp. 767-771 ◽  
Author(s):  
T. L. Slaminko ◽  
M. R. Miles ◽  
R. D. Frederick ◽  
M. R. Bonde ◽  
G. L. Hartman
Keyword(s):  
United States ◽  
New Species ◽  
The United States ◽  
Soybean Rust ◽  
Southern United States ◽  
Phakopsora Pachyrhizi ◽  
Legume Species ◽  
Causal Organism ◽  
Immunological Assay ◽  
Phaseolus Species

Phakopsora pachyrhizi, the causal organism of soybean rust, was first found in the continental United States in 2004 and has been found on soybean, kudzu, Florida beggarweed, and three Phaseolus species in the field. The pathogen has been reported to occur on more than 90 legume species worldwide and it is likely to infect native and introduced legume species in the United States. The objective of this study was to determine if 176 species representing 57 genera of legumes, the majority of which are either native or naturalized to soybean-growing areas of the United States, could be hosts of P. pachyrhizi. Between one and three accessions of each species, a total of 264 accessions, were inoculated with a mixture of four isolates of P. pachyrhizi. Severity and sporulation were rated on a 1-to-5 scale at 14 and 28 days after inoculation. P. pachyrhizi was confirmed by the presence of sporulating uredinia and/or immunological assay on 65 new species in 25 genera; 12 of these genera have not been reported previously as hosts. Many of the newly identified hosts grow in the southern United States, and like kudzu, could serve as overwintering hosts for P. pachyrhizi.

Phakopsora meibomiae (soybean rust).

2021 ◽  
Author(s):  
Keyword(s):  
Glycine Max ◽  
North America ◽  
South America ◽  
Host Range ◽  
Soybean Rust ◽  
Broad Host Range ◽  
Phakopsora Pachyrhizi ◽  
Legume Species ◽  
Asian Species ◽  
The World

Abstract P. meibomiae is a rust native to the tropical and subtropical regions of the Americas that has a broad host range among legume species. It infects soyabean (Glycine max), but is less aggressive on that host than the Asian soyabean rust species, Phakopsora pachyrhizi, which has invaded and spread widely throughout the Americas. Due to the fact that the American species has not caused epidemics on soyabean in South America or invaded North America, it can be considered to be much less invasive than the Asian species. Given its broad host range, the possibility exists that strains of P. meibomiae could be a threat to other legumes cultivated in warm parts of the world.

scholarly journals Epidemics of Soybean Rust (Phakopsora pachyrhizi) in Brazil and Paraguay from 2001 to 2003

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 675-677 ◽  
Author(s):  
J. T. Yorinori ◽  
W. M. Paiva ◽  
R. D. Frederick ◽  
L. M. Costamilan ◽  
P. F. Bertagnolli ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Sequence Analysis ◽  
Soybean Rust ◽  
Severe Drought ◽  
Phakopsora Pachyrhizi ◽  
Chain Reaction ◽  
Causal Organism ◽  
Mato Grosso ◽  
Polymerase Chain ◽  
The Cost

In 5 March 2001, a severe rust outbreak was recorded at Pitapó, Paraguay, and the causal organism was determined to be Phakopsora pachyrhizi using polymerase chain reaction (PCR) and DNA sequence analysis. In May, rust surveys showed spread throughout most of Paraguay and into western and northern Parana, Brazil. In the 2001-02 season, rust was widespread in Paraguay, but losses were reduced due to severe drought; however, in Brazil it spread to more than 60% of the soybean acreage, causing field losses estimated at 0.1 million metric tons (MMT). In 2003, the disease was observed in more than 90% of the fields in Brazil, and the projected losses in Mato Grosso and Bahia alone are 2.2 MMT (US$487.3 million). Approximately 80% of the soybean acreage in Brazil was sprayed twice with fungicides at the cost of US$544 million. Differences in efficacy have been observed among the commercial strobilurin and triazol fungicides.

scholarly journals Differential Responses of Resistant Soybean Entries to Isolates of Phakopsora pachyrhizi

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 224-228 ◽  
Author(s):  
T. A. Pham ◽  
M. R. Miles ◽  
R. D. Frederick ◽  
C. B. Hill ◽  
G. L. Hartman
Keyword(s):  
United States ◽  
Rust Resistance ◽  
Plant Introduction ◽  
Field Trials ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Limited Information ◽  
Sources Of Resistance ◽  
Reaction Patterns ◽  
Rust Resistance Genes

Soybean rust, caused by the fungus Phakopsora pachyrhizi, was detected in the continental United States in 2004. Several new sources of resistance to P. pachyrhizi have been identified in soybean (Glycine max); however, there is limited information about their resistance when challenged with additional U.S. and international isolates. Resistance of 20 soybean (G. max) entries was compared after inoculation with 10 P. pachyrhizi isolates, representing different geographic and temporal origins. Soybean entries included 2 universal susceptible cultivars, 4 sources of soybean rust resistance genes (Rpp1–4), and 4 and 10 resistant entries selected from field trials in Paraguay and Vietnam, respectively. Of the known Rpp1–4 sources of resistance, plant introduction (PI) 459025B (Rpp4) produced reddish-brown (RB) lesions in response to all of the P. pachyrhizi isolates, while PI 230970 (Rpp2) produced RB lesions to all isolates except one from Taiwan, in response to which it produced a susceptible tan (TAN) lesion. PI 200492 (Rpp1) and PI 462312 (Rpp3) produced TAN lesions in response to most P. pachyrhizi isolates. The resistant entries selected from Paraguay and Vietnam varied considerably in their responses to the 10 P. pachyrhizi isolates, with M 103 the most susceptible and GC 84058-18-4 the most resistant. The reaction patterns on these resistant entries to the P. pachyrhizi isolates were different compared with the four soybean accessions with the Rpp genes, indicating that they contain novel sources of rust resistance. Among the P. pachyrhizi isolates, TW 72-1 from Taiwan and IN 73-1 from India produced the most susceptible and resistant reactions, respectively, on the soybean entries.

scholarly journals First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Phaseolus spp. in the United States

Plant Disease ◽  
2006 ◽  
Vol 90 (7) ◽  
pp. 970-970 ◽  
Author(s):  
T. N. Lynch ◽  
J. J. Marois ◽  
D. L. Wright ◽  
P. F. Harmon ◽  
C. L. Harmon ◽  
...  
Keyword(s):  
United States ◽  
Phaseolus Vulgaris ◽  
The United States ◽  
Phaseolus Coccineus ◽  
Soybean Rust ◽  
Phaseolus Lunatus ◽  
Phakopsora Pachyrhizi ◽  
Causal Organism ◽  
Chain Reactions ◽  
Soybean Plants

Phakopsora pachyrhizi Syd. & P. Syd., the cause of soybean rust, was first observed in the continental United States in November 2004 (2). During the growing season of 2005, P. pachyrhizi was confirmed on soybean (Glycine max) and/or kudzu (Pueraria montana) in nine states in the southern United States. It is known that P. pachyrhizi has a much larger host range within the Fabaceae family. On 29 September 2005 in Quincy, FL, 45 entries of mostly large-seeded legumes were planted next to soybeans that were infected with P. pachyrhizi. Several seeds of each entry were planted on one hill. Soybean plants growing adjacent to these potential hosts had 15 to 25% of the leaf area affected, 95% incidence, and 73% defoliation on 16 November. On 7 December 2005, all the plants of Phaseolus coccineus L. (scarlet runner bean, PI311827), Phaseolus lunatus L. (lima bean, PI583558), and two Phaseolus vulgaris L. (kidney bean) cvs. Red Hawk and California Early Light Red Kidney (CELRK) were found to have leaves with suspected rust lesions. These plants were at physiological maturity but had not senesced. None of the hosts had been inoculated other than from spores produced by the adjacent rust-infected soybean plants or from unknown locations. On the basis of microscopic examination, suspected infected leaves from plants of the Phaseolus spp. had rust pustules characteristic of P. pachyrhizi uredinia. Uredinia were counted within a randomly selected 2-cm2 area of one leaf of each sample. The mean and range of uredinia per lesion for Phaseolus coccineus was 29 uredinia with a range of 0 to 3 uredinia per lesion, Phaseolus lunatus had 2 uredinia with 0 to 1 uredinium per lesion, Phaseolus vulgaris cv. Red Hawk had 22 uredinia with 0 to 5 uredinia per lesion, and Phaseolus vulgaris cv. CELRK had 43 uredinia with 0 to 4 uredinia per lesion. Polymerase chain reactions using two sets of primers (Ppa1/Ppa2 and Pme1/Pme2) were performed on DNA extracted from leaves of the three species with sporulating rust pustules (1). The results of these tests and further tests conducted by the USDA/APHIS confirmed that P. pachyrhizi was the causal organism for the observed rust. References: (1) P. F. Harmon et al. On-line publication. doi:10.1094/PHP-2005-0613-01-RS. Plant Health Progress, 2005. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 834-834 ◽  
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.

scholarly journals First Report of Phakopsora pachyrhizi, the Causal Organism of Soybean Rust in the Province of Misiones, Argentina

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 102-102 ◽  
Author(s):  
R. L. Rossi
Keyword(s):  
Field Trial ◽  
Personal Communication ◽  
Science Research ◽  
Middle Part ◽  
Research Field ◽  
Soybean Rust ◽  
Disease Spread ◽  
Phakopsora Pachyrhizi ◽  
Causal Organism ◽  
Maturity Groups

In April 2002, Phakopsora pachyrhizi Sydow was observed for the first time in L. N. Alem, in the Province of Misiones, Argentina. Misiones is nearly surrounded by Paraguay and Brazil, where P. pachyrhizi was discovered recently (2) and where it is a serious disease (3). Symptoms were observed on leaves in the upper half of plants at the R6 stage in a soybean research field trial. Symptoms included reddish-brown lesions on leaves especially on the abaxial surface, and uredinias were observed in the lesions with a 10× lens. Leaf defoliation was observed due to the disease after the R5 stage, and the enviroment (high humidity and air temperatures) was particularly conducive to the disease. The field trial area was 2,500 m2 and included soybean genotypes of maturity groups V to IX. Symptoms were detected in the later maturity groups. Field trials were surrounded by kudzu (Pueraria sp.), which is a common weed introduced in South America as a forage plant by Asian farmers, and it was reported as the main host of this pathogen in Paraguay (2). To confirm the identity of the pathogen, leaf samples from the middle part of plants were collected and sent to the Foreign Disease-Weed Science Research Unit, Ft. Detrick, MD. Samples were analyzed using a real-time polymerase chain reaction assay (1). Identification of P. pachyrhizi was confirmed the last week of May, 2002 (R. Frederick, personal communication). The soybean production area in Misiones is a small area in Argentina lying 600 km northeast of the main soybean area in the north central part of the country. SENASA (Servicio Nacional de Sanidad Vegetal [Nacional Service of Plant Health]) and SAGPYA (Secretary of Agriculture) were formally informed about these results on June 19, 2002. A program to assess the risk of disease spread is under development. References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) W. Morel Paiva. AnaisII Congresso Brasilero de Soja e Mercosoja. Foz de Iguazu, Brazil, 2002. (3) T. Yorinori. Anais II Congresso Brasilero de Soja e Mercosoja. Foz de Iguazu, Brazil, 2002.

scholarly journals Morphologic and Pathometric Characterization of the Asian Soybean Rust (Phakopsora pachyrhizi) on Kudzu (Pueraria lobata) in Argentina

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1132-1132
Author(s):  
M. A. Carmona ◽  
C. Fortugno ◽  
P. L. Achával
Keyword(s):  
Soybean Rust ◽  
Pueraria Lobata ◽  
Phakopsora Pachyrhizi ◽  
Adverse Conditions ◽  
Asian Soybean Rust ◽  
On Line ◽  
Misiones Province ◽  
Average Size ◽  
Important Disease

Asian soybean rust (ASR) is a very important disease caused by Phakopsora pachyrhizi. The disease has emerged as a major threat to soybean production in South America since 2001. During the 2003-2004 growing season, P. pachyrhizi spread rapidly throughout most soybean-growing areas of northwestern and northeastern Argentina (1). One widespread naturalized host in the northeastern part of the country is kudzu (Pueraria lobata). Plants of severely infected kudzu were sampled during January 2005 in Cerro Azul (29°29′S Misiones Province) to quantify P. pachyrhizi infection and morphologically characterize the fungus in leaves. The number of lesions, uredinia per cm2, and uredinia per lesion were recorded from the undersides of 50 leaflets that were visually showing rust symptoms. The average number of lesions and uredinia per cm2 was 14 (4 to 22), and 24 (5 to 78), respectively. The number of uredinia per lesion was 3 (1 to 10). Twenty leaflets from the lower canopy averaged 55 (42 to 78) uredinia per cm2. The average size of urediniospores was 18.4 μm wide (12.5 to 22.5) and 22.7 μm long (17.5 to 26.3). Although important epidemics of ASR have not been registered on soybean crops in January (2) because of adverse conditions, the fungus was observed on kudzu plants. To our knowledge, this is the first report of morphologic and pathometric characterization of P. pachyrhizi on kudzu in Argentina. References: (1) M. A. Carmona et al Plant Dis. 89:109, 2005. (2) SINAVIMO, Sistema Nacional Argentino de Vigilancia y Monitoreo de plagas. Roya de la soja: Resultados de la campaña 2004-2005. On-line publication. SENASA, 2005.

scholarly journals Prediction of Short-Distance Aerial Movement of Phakopsora pachyrhizi Urediniospores Using Machine Learning

2017 ◽  
Vol 107 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
L. Wen ◽  
C. R. Bowen ◽  
G. L. Hartman
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Short Distance ◽  
Soybean Rust ◽  
Machine Learning Techniques ◽  
Phakopsora Pachyrhizi ◽  
Primary Means ◽  
Soybean Plants ◽  
Selection Operator ◽  
Active Trap

Dispersal of urediniospores by wind is the primary means of spread for Phakopsora pachyrhizi, the cause of soybean rust. Our research focused on the short-distance movement of urediniospores from within the soybean canopy and up to 61 m from field-grown rust-infected soybean plants. Environmental variables were used to develop and compare models including the least absolute shrinkage and selection operator regression, zero-inflated Poisson/regular Poisson regression, random forest, and neural network to describe deposition of urediniospores collected in passive and active traps. All four models identified distance of trap from source, humidity, temperature, wind direction, and wind speed as the five most important variables influencing short-distance movement of urediniospores. The random forest model provided the best predictions, explaining 76.1 and 86.8% of the total variation in the passive- and active-trap datasets, respectively. The prediction accuracy based on the correlation coefficient (r) between predicted values and the true values were 0.83 (P < 0.0001) and 0.94 (P < 0.0001) for the passive and active trap datasets, respectively. Overall, multiple machine learning techniques identified the most important variables to make the most accurate predictions of movement of P. pachyrhizi urediniospores short-distance.

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