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

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 111-111 ◽  
Author(s):  
A. J. Ivancovich ◽  
G. Botta ◽  
M. Rivadaneira ◽  
E. Saieg ◽  
L. Erazzú ◽  
...  
Keyword(s):  
Growing Season ◽  
Soybean Rust ◽  
Field Bean ◽  
Growth Stages ◽  
Phakopsora Pachyrhizi ◽  
Bean Plants ◽  
Northwestern Region ◽  
Uromyces Phaseoli ◽  
Soybean Plants ◽  
Field Plots

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi Syd. & P. Syd., has been reported in Argentina on soybean (Glycine max) and kudzu (Pueraria lobata and Pueraria javanica) since the 2002 growing season (1–4). On 29 May 2006, plants of Phaseolus spp. were found to have tan ASR-like rust lesions on leaves at eight different field plots located in the northwestern province of Salta, Argentina. Growth stages of infected bean plants within plots were between pod setting and physiological maturity. Diagnosis of ASR on bean leaves was performed with a stereoscopic microscope to view rust pustules, and suspected uredinia of P. pachyrhizi were observed, furthermore, typical ASR urediniospores also were also observed at ×400. ELISA and PCR methods gave positive results for ASR. Rust spores from these plants were used to inoculate soybean plants at the V3 growth stage with rust spores from field bean plants produced under greenhouse conditions. Typical ASR tan pustules developed within 21 days of inoculation. Bean rust caused by Uromyces phaseoli also was seen in some of the bean plots but was easily differentiated from ASR because the uredinia were much darker and affected the upper leaves, while the ASR uredinia were lighter and spread from the lower leaves to the upper leaves. This finding is of significance in Argentina because bean is an important crop grown in the northwestern region of the country and is planted approximately 2 months after soybean planting. Given this planting time difference, bean may provide an overwintering host for the survival of ASR spores, thereby providing a green bridge for infection of soybean plants during the following growing season. References: (1) A. J. Ivancovich. Soybean rust situation in Argentina. Oral presentation. Symposium: Soybean Rust: Too Close for Comfort. Annual Meeting of the American Phytopathological Society. 2003. (2) A. J. Ivancovich. Plant Dis. 89:667, 2005. (3) A. J. Ivancovich and G. Botta. Rev. Tecnología Agropecuaria 7(21):16, 2002. (4) A. J. Ivancovich et al. Phytopathology (Abstr.) 94(suppl.):S44, 2004.

scholarly journals Morphologic and Pathometric Characterization of the Asian Soybean Rust (Phakopsora pachyrhizi) in Santa Fe Province, Argentina

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 684-684 ◽  
Author(s):  
R. N. Pioli ◽  
M. V. Cambursano ◽  
E. N. Morandi
Keyword(s):  
Growing Season ◽  
Brown Spot ◽  
Soybean Rust ◽  
Disease Spread ◽  
Phakopsora Pachyrhizi ◽  
Santa Fe ◽  
Asian Soybean Rust ◽  
Soybean Plants ◽  
Soybean Leaves

The Asian soybean rust caused by the fungus Phakopsora pachyrhizi was cited for the first time in Argentina during the 2002-2003 growing season (3). During 2003-2004, the disease spread to other northern provinces and was also observed in north-central Santa Fe, the main producing soybean province of the country. Because the disease appeared at the end of the crop growing season (late March to early April) it had little or no impact on crop yields. The objectives of this study were to characterize morphologically and pathometrically the disease on soybean and check the presence of P. pachyrhizi on volunteer soybean plants that could eventually carry the disease to the next growing season. The study was conducted in the San Justo Department, Santa Fe Province (between 30 and 31°S latitude), where the presence of the soybean rust was molecularly confirmed by Sistema Nacional Vigilancia y Monitoreo (on-line publication at www.sinavimo.gov.ar ). Three field locations were sampled and identified as M1, M2, and M3. Transversal cuts of soybean leaves through rust lesions and histo-pathological staining were used for micromor-phologic characterization of the developmental stages of P. pachyrhizi. The disease incidence was estimated as the proportion of affected soybean plants and leaves. Average severity, expressed as the percentage of leaf area affected, including chlorosis, was measured on the terminal leaflet of leaves sampled from the lower one-third of the canopy. Three replicates of 10 plants, randomly chosen, were used. The number of uredinia per square centimeter and per lesion (symptomatic foliar area showing chlorosis and necrosis caused by the fungus) was measured on the undersides of the sampled leaflets at ×40 magnification (1). Typical signs and symptoms of P. pachyrhizi coexisted on soybean leaves with brown spot (Septoria glycines), downy mildew (Peronospora manshurica), anthracnose (Colletotrichum truncatum), and blight and leaf spot (Cercospora kikuchii) and also with bacteria (Pseudomonas and Xanthomonas spp.). Uredinia and telia of the P. pachyrhizi cycle were observed. Uredinia were also observed on soybean petioles. The average size of urediniospores (n = 60) was 23.3 × 16.6 μm. Telia were located adjacent to the uredinia. These telia were dark and crusty with four stacked layers of teliospores. Rust incidence in plants was 100% for the three fields, while the incidence in leaves was 100% for M1 and M2 and 60% for M3. Average disease severity was 50.3, 25.6, and 14.8% for M1, M2, and M3, respectively. The mean number of uredinia per square centimeter was 327, 179, and 177, for M1, M2, and M3, respectively. The number of uredinia per lesion ranged from 1 to 6. P. pachyrhizi was also found on volunteer soybean plants that emerged shortly after harvest. On 40 leaflets, the foliar incidence was 25%, showing one to two lesions with one to two uredinios per leaflet (2). The volunteer soybean plants could constitute a potential early source of inoculum. References: (1) M. Marcchetti et al. Phytopathology. 66:461, 1976. (2) R. Pioli et al. La roya asiática en Santa. Fe, Arg. XII Cong. AAPRESID, II Sem. Internac. Soja, Arg. 283–290, 2004. (3) R. L. Rossi. Plant Dis. 87:102, 2003.

scholarly journals Overwinter and Survival of Asian Soybean Rust Caused by Phakopsora pachyrhizi in Volunteer Soybean Plants in Entre Ríos Province, Argentina

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 826-826 ◽  
Author(s):  
A. N. Formento ◽  
J. de Souza
Keyword(s):  
Growing Season ◽  
Soybean Rust ◽  
Limiting Factor ◽  
Research Station ◽  
Phakopsora Pachyrhizi ◽  
Asian Soybean Rust ◽  
On Line ◽  
Freezing Temperatures ◽  
Soybean Plants ◽  
Entre Rios

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi was initially reported in the Province of Entre Ríos, Argentina in April 2004 (1). During the 2004-2005 growing season, ASR was observed in the main soybean-producing (Glycine max) region of the country (4) and it was observed on kudzu (Pueraria lobata) in Misiones and Santa Fe provinces (2). Of the environmental factors affecting rust survival over the winter, temperature is probably the most important one with no germination occurring below 7°C (3). The objectives of this study were to analyze the subfreezing daily air temperatures in the presence of new erumpent uredinia and the germination of P. pachyrhizi urediniospores. Ten sites with volunteer plants close to the meteorological station were found in the Paraná Research Station (31°51′S, 60°31′W). Weekly, from June 2004 through December 2005, sites were randomly sampled for volunteer plants (n = 15). The presence of the ASR was confirmed with a polymerase chain reaction (PCR) assay by SINAVIMO (4). The ASR incidence (ASRI) and erumpent uredinia incidence (EUI) was estimated as the proportion of affected plants. Uredinia were classified as: new erumpent with colorless spores; mature cinnamon with pale cinnamon-brown spores; and dead, empty, and dark without spores. The disease density was estimated as an average of the diseased leaflets according to the following scale: light (number of lesions 1 to 100), moderate (101 to 500), and heavy (>500). The ability of urediniospores from the erumpent pustules to germinate was tested during July 2004 and September 2005 on 1.5% of water agar and kept at 25 ± 2°C for 2 days. The subfreezing daily air (0.05 m height) temperature was registered. During the complete evaluation period, surviving plants from the Vc to R6 stages were observed. However, plants with ASR were only observed from June to July 2004 and May to September 2005. Locally, first planting dates begin in October. New uredinia were observed close to mature and dead uredinia on unifoliate and trifoliate leaflets, and petiols and stems in plants from the V2 to R5 stages. There were 13 days with below freezing temperatures from 1 June to 31 July 2004 (-0.1 to -7.4°C), and ASRI and EUI was 100%. The ASR mean density was light. The coldest temperature was -7.4°C on 11 July 2004, and thereafter, no uredinia were observed until the next growing season. From 25 April to 16 September 2005 there were 20 days with below freezing temperatures (-0.1 to -4.9°C). The ASRI and the EUI were 92.3 (76.9), 75.0 (58.3), 59.1 (32.6), 50.0 (40.9), and 36.7 (23.3)% in May, June, July, August, and September, respectively. The incidence of plants with a moderate to heavy disease level was 50.0, 41.7, 28.6, 29.5, and 10% respectively. Germination rate of urediniospores collected in July 2004 was 11% and 28% in September 2005. Low temperatures do not seem to be a limiting factor for the survival of P. pachyrhizi, and urediniospores could survive on volunteer plants until new soybean plants grow. Since another host is rare or absent in the region, volunteer soybean plants may provide a reservoir of inoculum for the next season. References: (1) A. N. Formento. Roya de la soja en Entre Ríos. INTA-EEA Paraná. On-line publication. INTA, 2004. (2) A. N. Formento and J. de Souza. INTA-EEA Paraná. Serie Extensión No. 32, 2004. (3) M. Marchetti et al. Phytopathology 66:461, 1975. (4) SINAVIMO. Sistema Nacional Argentino de Vigilancia y Monitoreo de Plagas, Roya de la soja. On-line publication. SENASA, 2004.

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.

scholarly journals An Overview of the Epidemiology of Phakopsora pachyrhizi in the State of Mato Grosso, Brazil

2021 ◽  
Vol 13 (6) ◽  
pp. 110
Author(s):  
Erlei Melo Reis ◽  
Wanderlei Dias Guerra ◽  
Mateus Zanatta ◽  
Laércio Zambolim
Keyword(s):  
Environmental Effect ◽  
The State ◽  
Soybean Rust ◽  
Economic Sustainability ◽  
Phakopsora Pachyrhizi ◽  
Airborne Spores ◽  
Mato Grosso ◽  
Asian Soybean Rust ◽  
Weed Plants ◽  
Soybean Plants

This review seeks to expand the knowledge about the epidemiology of Asian sybean rust in the state of Mato Grosso and contribute to ensuring the economic sustainability of soybean crop. It is discussed the Phakopsora pachyrhizi potential of dispersal from Asia to South America and finally to Mato Grosso state. The origin of the Asian soybean rust inoculum within Mato Grosso is addressed by the survival in volunteer and soybean weed plants (Pitelli, 2015) in other crops such as cotton. Data on the adverse environmental effect on the soybean plants survival are shown mainly the water deficit from June to August. Reports on the effect air temperature and mainly solar radiation on the mortality of airborne spores during their anemophilous spread on sunny days are also discussed. This increase of knowledge aims to make the soybean-free period more efficient by the knowledge on the soybean plants survival and on the fungus viability in the month of August. Due to the proximity of soybean farms, during the soybean-free period, in other states (Tocantins, Goi&aacute;s, Rond&ocirc;nia, etc.) and in other neighbor countries we discuss the likelihood that inoculum in the state may also originate in out-of-state crops during the Mato Grosso soybean-free period.

scholarly journals Reduced Asian Soybean Rust Control by Commercial Fungicides Co-formulations in the 2018-2019 Growing Season in Southern Brazil

2021 ◽  
Vol 13 (4) ◽  
pp. 113
Author(s):  
Erlei Melo Reis ◽  
Mateus Zanatta ◽  
Andrea Camargo Reis
Keyword(s):  
Block Design ◽  
Soybean Rust ◽  
Growth Stages ◽  
Phakopsora Pachyrhizi ◽  
Southern Brazil ◽  
Control Efficacy ◽  
Growing Seasons ◽  
Asian Soybean Rust ◽  
Randomized Block Design ◽  
Commercial Fungicide

It has been a growers concen the reduction of Asian soybean rust (ASR) control by commercial fungicide co-formulations in the last growing seasons in southern Brazil. The objective of this work was to assess the ASR control efficacy by the most used co-formulations in the 2018/19 season. In a field experiment, 19 fungicides in commercial formulations to control soybean rust caused by Phakopsora pachyrhizi, were evaluated. Chemicals at their recommended doses were sprayed at four soybean growth stages. The first application was performed with 1.82% leaflet incidence and coinciding with R1 phenological stage. The others were performed at 14-18 days intervals. At stage R6, end of the epidemic and coinciding with half of the defoliation in the control plots, the leaf severity was appraised. The experiment was conducted with Ativa soybean cultivar, in 3 &times; 6 m plots, four replications and randomized block design. The harvest was made with a plot combine and the yield expressed in grains kg/ha. The means were compared by the Scott-Knott test. The disease control efficacy by 17 fungicide co-formulation showed control less than 57%, one with 78% and none with &ge; 80%. The unsprayed treatment severity was 81% and the greatest control of 78% resulted in 3,876 kg/ha yield. Therefore, the hypothesis raised in this work was accepted showing that the site-specific fungicides co-formulations are showing efficacy reduction season after season.

Use of a Canopy Opener in Fungicide Applications to Improve Asian Soybean Rust Control

2017 ◽  
Vol 60 (6) ◽  
pp. 1819-1825 ◽  
Author(s):  
Bianca Moura ◽  
Carolina Cardoso Deuner ◽  
Gustavo Luiz Visintin ◽  
Walter Boller
Keyword(s):  
Grain Yield ◽  
Plant Architecture ◽  
Spray Deposition ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Droplet Deposition ◽  
Asian Soybean Rust ◽  
Negative Effect ◽  
Soybean Plants ◽  
Pesticide Deposition

Abstract. In soybeans, the leaves of the upper canopy often act as a shield against fungicide penetration, preventing pesticide deposition on target. Fungicide applications to control Asian soybean rust (ASR) are especially difficult because the infection usually starts on the lower canopy. In this study, soybean plants of an early indeterminate cultivar and a determinate cultivar were sprayed with the fungicide azoxystrobin + benzovindiflupyr at six different times of the day with or without the addition of a curtain of chains on the spray boom, which acted as a canopy opener. The number of uredia of cm-2 and grain yield were measured to evaluate application efficacy. We found that the use of the curtain of chains reduced ASR control on the upper canopy for the indeterminate cultivar; however, less of a negative effect was observed for the determinate cultivar. The curtain of chains improved ASR control on the lower and middle canopies at more hours of the day for the determinate cultivar. For both cultivars, the curtain of chains increased ASR control at 6:00, 9:00, and 18:00 h on the lower canopy. Grain yield was also higher with the curtain of chains at 6:00 and 9:00 h for the determinate cultivar. Our results showed that using the curtain of chains could improve fungicide droplet deposition on the lower canopy, leading to greater ASR control and possibly increasing yield. However, it is important to consider the plant architecture and hour of application to maximize the benefit of the curtain of chains. Keywords: Canopy opener, Fungicide penetration, Phakopsora pachyrhizi, Plant architecture, Spray deposition.

scholarly journals Effect of Silicon Absorption on Soybean Resistance to Phakopsora pachyrhizi in Different Cultivars

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Geneviève Arsenault-Labrecque ◽  
James G. Menzies ◽  
Richard R. Bélanger
Keyword(s):  
Glycine Max ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Chemical Analyses ◽  
Disease Symptoms ◽  
Soybean Cultivars ◽  
Soybean Resistance ◽  
Soybean Plants ◽  
Si Content ◽  
Innate Ability

Silicon (Si) is recognized for its prophylactic role in alleviating diseases when absorbed by plants and has been proposed as a possible solution against soybean rust, caused by Phakopsora pachyrhizi. However, little is known about its potential effects on soybean (Glycine max) because the plant's ability to absorb Si is poorly defined. In this work, our objectives were to evaluate and quantify the absorption of Si in leaves of different soybean cultivars and to determine if such absorption was able to enhance resistance to soybean rust. In a first set of experiments with cv. Williams 82, hydroponic plants were supplied or not with Si and inoculated with urediniospores of P. pachyrhizi. Chemical analyses revealed no significant differences in the plants' Si content regardless of the treatment, which translated into no effect on rust incidence. However, in a second set of experiments with different cultivars, plants of Korean cultivar Hikmok sorip absorbed nearly four times more Si than those of Williams 82. At the same time, plants from this cultivar exhibited a near absence of disease symptoms when supplied with Si. This resistance appeared to be the result of hypersensitive (HR) reactions that were triggered when plants were fed with Si. These results support the concept that a plant's innate ability to absorb Si will dictate the benefits conferred by a treatment with Si and provide evidence that Si can protect soybean plants against soybean rust through mediated resistance.

CONTRIBUTION OF N2 FIXATION TO FIELD BEAN AND PEA N UPTAKE OVER THE GROWING SEASON UNDER FIELD CONDITIONS IN SOUTHERN ALBERTA

1989 ◽  
Vol 69 (3) ◽  
pp. 695-699 ◽  
Author(s):  
R. M. N. KUCEY
Keyword(s):  
Phaseolus Vulgaris ◽  
Pisum Sativum ◽  
N Uptake ◽  
Growing Season ◽  
Field Conditions ◽  
Field Bean ◽  
Phaseolus Vulgaris L ◽  
Bean Plants ◽  
Southern Alberta

Dinitrogen fixation with field bean (Phaseolus vulgaris L. 'GN1140') and pea (Pisum sativum L. 'Trapper') over the growing season under field conditions was determined using 15N isotope dilution methods. Levels of N2 fixation were low during the early part of the growing season for both bean and pea, and increased later in the growing season. At physiological maturity, GN1140 fixed over 91 kg N ha−1, contributing between 60 and 90% of the N in the bean plants. Pea fixed 117 kg N ha−1, which constituted a maximum of 57% of the pea plant N. More N was contained in the bean and pea pods than was fixed over the growing season. Key words: Bean (field), pea, Phaseolus vulgaris, Pisum sativum, 15N dilution

Effects of inflorescence removal on interactions between reproductive storage sites of field beans (Vicia faba) under different shading treatments

1991 ◽  
Vol 116 (3) ◽  
pp. 409-415 ◽  
Author(s):  
W. Aufhammer ◽  
I. Götz-Lee
Keyword(s):  
Seed Weight ◽  
Field Experiments ◽  
Storage System ◽  
High Light ◽  
Field Bean ◽  
Growth Stages ◽  
Minor Importance ◽  
Yield Traits ◽  
Bean Plants ◽  
Field Beans

SUMMARYIn studies of two indeterminate cultivars in field experiments in 1985 and 1986 at Hohenheim University, the hierarchy within the reproductive storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes. Shading reduced pod set and seed weight mainly at basal nodes. Increasing plant population density reduced seed yield traits at all nodes. Removal of basal inflorescences increased pod set and seed weight at the remaining nodes, especially the lower ones. The favourable effects were greater under high light intensities and in sparse stands. The growth stages at which the basal inflorescences were removed and the removal of apical inflorescences were of minor importance.

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