scholarly journals Adult Plant Evaluation of Soybean Accessions for Resistance to Phakopsora pachyrhizi in the Field and Greenhouse in Paraguay

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 96-105 ◽  
Author(s):  
M. R. Miles ◽  
W. Morel ◽  
J. D. Ray ◽  
J. R. Smith ◽  
R. D. Frederick ◽  
...  
Keyword(s):  
Field Trial ◽  
Field Experiments ◽  
Field Evaluation ◽  
Soybean Rust ◽  
Adult Plant ◽  
Phakopsora Pachyrhizi ◽  
Sources Of Resistance ◽  
Plant Evaluation ◽  
Maturity Groups

Five hundred thirty soybean accessions from maturity groups (MG) III through IX were evaluated for resistance to Phakopsora pachyrhizi in a replicated field trial at Centro Regional de Investigación Agrícola in Capitán Miranda, Itapúa, Paraguay during the 2005–06 season. Soybean rust severities of individual accessions ranged from 0% (resistant) to 30.0% (susceptible). In MG III and IV, the most resistant accessions were PI 506863, PI 567341, and PI 567351B, with severities less than 1.2%. In MG V, the most resistant accessions were PI 181456, PI 398288, PI 404134B, and PI 507305, with severities less than 0.3%. In MG VI, the most resistant accessions were PI 587886, PI 587880A, and PI 587880B, with severities less than 0.3%. In MG VII and VIII, the most resistant were PI 587905 and PI 605779E, with severities less than 1.0%. In MG IX, the most resistant accessions were PI 594754, PI 605833, PI 576102B, and PI 567104B, with severities less than 1.0%. The resistance in 10 selected accessions from MG VI, VII, VIII, and XI was confirmed in subsequent greenhouse and field experiments where severities of 0.4% or less and reddish-brown lesions with sporulation levels less than 3.0 were observed. These accessions, with low severities in the adult plant field evaluation, may be new sources of resistance to P. pachyrhizi.

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 Systems of aerial spraying for soybean rust control

2011 ◽  
Vol 31 (4) ◽  
pp. 695-703 ◽  
Author(s):  
Ulisses R. Antuniassi ◽  
Edivaldo D. Velini ◽  
Rone B. de Oliveira ◽  
Maria A. Peres-Oliveira ◽  
Zulema N. Figueiredo
Keyword(s):  
Relative Humidity ◽  
Confidence Interval ◽  
Field Trial ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Aerial Application ◽  
Fungicide Application ◽  
Set Up ◽  
Cotton Oil ◽  
Electrostatic System

The soybean rust caused by Phakopsora pachyrhizi is considered the main soybean disease and consequently the appropriate selection and the use of spraying equipment are vital for its control. The aim of this study was to evaluate the performance of aerial application equipment for soybean rust control. It was used: Micronair AU 5000 at 10 L ha-1 (with oil) and at 20 L ha-1 (without oil); Stol ARD atomizer at 10 and 20 L ha-1 (both with oil) and Spectrum (electrostatic) at 10 L ha-1 (without oil). The adjuvant was cotton oil (1.0 L ha-1) with emulsifier (BR 455) at 0.025 L ha-1. The field trial was set up at the 3rd fungicide application, when f four replications of each treatment. There were no statistical differences among treatments related to fungicide deposits by at a Confidence Interval of 95%. It was observed that the best results were obtained with Micronair (10 L ha-1 with oil), Stol (20 L ha-1 with oil) and electrostatic system at 10 L ha-1 with the lowest relative humidity (64%).

scholarly journals Evaluation of Virulence of Phakopsora pachyrhizi and P. meibomiae Isolates

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 708-716 ◽  
Author(s):  
M. R. Bonde ◽  
S. E. Nester ◽  
C. N. Austin ◽  
C. L. Stone ◽  
R. D. Frederick ◽  
...  
Keyword(s):  
Partial Resistance ◽  
Major Gene ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Sources Of Resistance ◽  
Agricultural Industry ◽  
Time Of Year ◽  
First Time ◽  
The U.S

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi and recently discovered for the first time in continental United States, has been of concern to the U.S. agricultural industry for more than 30 years. Since little soybean rust resistance is known, and resistance is often difficult to detect or quantitate, we initiated a project to develop a better, more quantitative, method. The methodology determined the average numbers and diameters of uredinia in lesions that developed on leaves of inoculated plants 14 days after inoculation. It was used to compare virulence of P. pachyrhizi isolates from Asia and Australia and P. meibomiae from Puerto Rico and Brazil, collected as many as 30 years earlier, with isolates of P. pachyrhizi recently collected from Africa or South America. Susceptible reactions to P. pachyrhizi resulted in tan-colored lesions containing 1 to 14 uredinia varying greatly in size within individual lesions. In contrast, on these same genotypes at the same time of year, resistance to other P. pachyrhizi isolates was typified by 0 to 6 small uredinia in reddish-brown to dark-brown lesions. Using appropriate rust resistant and rust susceptible genotypes as standards, examination of uredinia 14 days after inoculation allowed quantitative comparisons of sporulation capacities, one measure of susceptibility or resistance to soybean rust. The study verified the presence and ability to detect all known major genes for resistance to soybean rust in the original sources of resistance. It demonstrated that soybean lines derived from the original PI sources, and presumed to possess the resistance genes, in actuality may lack the gene or express an intermediate reaction to the rust pathogen. We suggest that a determination of numbers and sizes of uredinia will detect both major gene and partial resistance to soybean rust.

scholarly journals Effects of Silicon Applications on Soybean Rust Development Under Greenhouse and Field Conditions

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 317-324 ◽  
Author(s):  
E. M. Lemes ◽  
C. L. Mackowiak ◽  
A. Blount ◽  
J. J. Marois ◽  
D. L. Wright ◽  
...  
Keyword(s):  
Field Experiments ◽  
Production Systems ◽  
Disease Onset ◽  
The United States ◽  
Plant Diseases ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Soybean Production ◽  
Progress Curve ◽  
Production Areas

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is one of the most destructive fungal diseases affecting soybean production. Silicon (Si) amendments were studied as an alternative strategy to control SBR because this element was reported to suppress a number of plant diseases in other host–pathogen systems. In greenhouse experiments, soybean cultivars inoculated with P. pachyrhizi received soil applications of wollastonite (CaSiO3) (Si at 0, 0.96, and 1.92 t ha–1) or foliar applications of potassium silicate (K2SiO3) (Si at 0, 500, 1,000, or 2,000 mg kg–1). Greenhouse experiment results demonstrated that Si treatments delayed disease onset by approximately 3 days. The area under disease progress curve (AUDPC) of plants receiving Si treatments also was significantly lower than the AUDPC of non-Si-treated plants. For field experiments, an average 3-day delay in disease onset was observed only for soil Si treatments. Reductions in AUDPC of up to 43 and 36% were also observed for soil and foliar Si treatments, respectively. Considering the natural delayed disease onset due to the inability of the pathogen to overwinter in the major soybean production areas of the United States, the delay in disease onset and the final reduction in AUDPC observed by the soil Si treatments used may lead to the development of SBR control practices that can benefit organic and conventional soybean production systems.

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.

Evaluation of Selected Genotypes of Soybean for Resistance to Phakopsora pachyrhizi

2009 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
S. Li ◽  
L. D. Young
Keyword(s):  
Rust Fungus ◽  
Soybean Rust ◽  
Information Network ◽  
Phakopsora Pachyrhizi ◽  
Sources Of Resistance ◽  
Plant Introductions ◽  
Severity Rating ◽  
Resistant Lines ◽  
Lesion Type ◽  
Glycine Max L

Soybean rust, caused by Phakopsora pachyrhizi Syd. & P. Syd., is one of the most destructive diseases of soybean [Glycine max (L.) Merr.] worldwide. To identify sources of resistance to domestic soybean rust fungus populations for plant breeding, our strategy has been to evaluate soybean lines that were previously identified as resistant to foreign isolates. In this study, two sets of plant introductions (PI) were evaluated using P. pachyrhizi urediniospores collected in Mississippi in 2006. The first set of PIs contained 10 lines previously identified as resistant in Paraguay, four PIs with known single genes for resistance to P. pachyrhizi, and Freedom and Williams 82 as susceptible checks. The second set included 17 lines that were selected based on information from Germplasm Resources Information Network (GRIN) and susceptible Williams 82. PI567102B was one of the most resistant lines to a Mississippi bulk isolate of P. pachyrhizi with the lowest severity rating, no sporulation, and red-brown lesion type. Accepted for publication 25 April 2009. Published 15 June 2009.

scholarly journals Spray volume deposits and fungicide efficacy on soybean rust (Phakopsora pachyrhizi)

2019 ◽  
pp. 1698-1705
Author(s):  
Evandro Pereira Prado ◽  
Carlos Gilberto Raetano ◽  
Mario Henrique Ferreira do Amaral Dal Pogetto ◽  
Rafael de Souza Christovam ◽  
Paulo Renato Matos Lopes ◽  
...  
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Control Efficacy ◽  
Application Techniques ◽  
Application Methods ◽  
Spray Volume ◽  
Soybean Leaves ◽  
Thousand Seed Weight

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is one of the most destructive fungal diseases affecting soybean yields in many countries. Fungicide application methods that provide better SBR control efficacy may reduce soybean losses due to this disease. We investigated the effects of spray volumes applying the fungicide pyraclostrobin plus epoxiconazol at 133 + 50 g a.i. ha-1 by a conventional sprayer (CS) and an air-assisted sprayer (AAS). Field experiments were conducted comparing the effects of spray volumes of 110, 160, and 210 L ha-1 and two application techniques (CS and AAS) on spray deposits and SBR control. Fungicide efficacies were measured by disease severity, thousand seed weight, and yield. Correlations between disease severity and yield were also assessed. All treatments were applied with an Advance 2000 AM18 sprayer. In general, SBR disease and yield did not differ significantly when fungicide applications were applied with AAS compared to CS. Increasing the spray volume from 110 to 210 L ha-1 did not increase spray deposit coverage on soybean leaves. Low disease severity was obtained by fungicide applications using a spray volume of 210 L ha-1. Safe recommendations of ground spray volumes for SBR control should be between 160 and 210 L ha-1, using hydraulic nozzles.

Field Evaluation of Soybean for Mexican Bean Beetle Resistance. II. Maturity Groups III, IV, and V

Crop Science ◽  
1990 ◽  
Vol 30 (2) ◽  
pp. 374 ◽  
Author(s):  
M. E. Kraemer ◽  
M. Rangappa ◽  
T. Mebrahtu ◽  
P. S. Benepal
Keyword(s):  
Field Evaluation ◽  
Mexican Bean Beetle ◽  
Bean Beetle ◽  
Maturity Groups

Assessment of sowing dates and plant densities using CSM-CROPGRO-Soybean for soybean maturity groups in low latitude

2021 ◽  
pp. 1-14
Author(s):  
L. S. Sampaio ◽  
R. Battisti ◽  
M. A. Lana ◽  
K. J. Boote
Keyword(s):  
Management Practices ◽  
Field Experiments ◽  
Plant Density ◽  
Crop Model ◽  
Management Scenarios ◽  
Low Latitude ◽  
Area Index ◽  
Sowing Dates ◽  
Plant Densities ◽  
Maturity Groups

Abstract Crop models can be used to explain yield variations associated with management practices, environment and genotype. This study aimed to assess the effect of plant densities using CSM-CROPGRO-Soybean for low latitudes. The crop model was calibrated and evaluated using data from field experiments, including plant densities (10, 20, 30 and 40 plants per m2), maturity groups (MG 7.7 and 8.8) and sowing dates (calibration: 06 Jan., 19 Jan., 16 Feb. 2018; and evaluation: 19 Jan. 2019). The model simulated phenology with a bias lower than 2 days for calibration and 7 days for evaluation. Relative root mean square error for the maximum leaf area index varied from 12.2 to 31.3%; while that for grain yield varied between 3 and 32%. The calibrated model was used to simulate different management scenarios across six sites located in the low latitude, considering 33 growing seasons. Simulations showed a higher yield for 40 pl per m2, as expected, but with greater yield gain increments occurring at low plant density going from 10 to 20 pl per m2. In Santarém, Brazil, MG 8.8 sown on 21 Feb. had a median yield of 2658, 3197, 3442 and 3583 kg/ha, respectively, for 10, 20, 30 and 40 pl per m2, resulting in a relative increase of 20, 8 and 4% for each additional 10 pl per m2. Overall, the crop model had adequate performance, indicating a minimum recommended plant density of 20 pl per m2, while sowing dates and maturity groups showed different yield level and pattern across sites in function of the local climate.

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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