scholarly journals Bacillus thuringiensis Combined With Fungicide Applications in the Management of Soybean Leaf Diseases

2019 ◽  
Vol 11 (13) ◽  
pp. 226
Author(s):  
Mônica A. Müller ◽  
Ana C. Klosowski ◽  
Maristella Dalla Pria ◽  
Sérgio M. Mazaro ◽  
Louise L. May De Mio
Keyword(s):  
Bacillus Thuringiensis ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Yield Losses ◽  
Resistance Induction ◽  
Foliar Diseases ◽  
Asian Soybean Rust ◽  
Soybean Leaf

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is the main soybean leaf disease in Brazil. Downy mildew (Peronospora manshurica) and powdery mildew (Microsphaera diffusa) are important soybean foliar diseases of occurrence in Paraná state. To reduce severity and yield losses caused by soybean foliar diseases, this work aimed to verify the efficacy of different application doses of the commercial product Dipel® Bacillus thuringiensis (Bt), which is a biological insect controller, combined with number of Opera® fungicide (pyraclostrobin + epoxiconazole) intercalated applications, and to investigate the effect of the Bt Dipel® in the resistance induction of soybean. For this study, different methodologies were used, including in vitro, in vivo and field assays. The results showed that Bt Dipel® can reduce soybean foliar diseases by inducing β-1,3 glucanase enzime and phytoalexin gliceolin. The fungicide application in the experiment condition reduced yield losses.

scholarly journals In vivo sensitivity of Phakopsora pachyrhizi to fungicides

2020 ◽  
Vol 50 (1) ◽  
Author(s):  
Amanda Chechi ◽  
Valéria Cecília Ghissi-Mazetti ◽  
Elias Zuchelli ◽  
Carolina Cardoso Deuner ◽  
Carlos Alberto Forcelini ◽  
...  
Keyword(s):  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Copper Oxychloride ◽  
Toxic Activity ◽  
Site Specific ◽  
Fungicide Application ◽  
Asian Soybean Rust ◽  
Randomized Design ◽  
Completely Randomized Design

ABSTRACT: Asian soybean rust is one of the most destructive diseases that can be found in this crop. It can be largely controlled by fungicide application. The objective was to assess the sensitivity of P. pachyrhizi isolates to fungicides. The tests were performed in a completely randomized design, with six replicates. The sensitivity of twelve isolates to site-specific and multisite fungicides at concentrations of 0.1; 1.0; 10.0, and 100.0 mg L-1, plus a control with absence of fungicide (0.0 mg L-1) was assessed. Soybean leaflets were immersed in the appropriate fungicide solutions, disposed in wet chambers in plastic boxes, and inoculated using each uredinia suspension of P. pachyhrizi (5.0 x 104 uredospores mL-1), separately. Boxes were incubated for 20 days at a temperature of 23°C and a 12-hour photoperiod. Next, the number of uredinia per cm2 on the abaxial face of each leaflet was evaluated. The active ingredients prothioconazole, trifloxystrobin, fluxapiroxade, trifloxystrobin + prothioconazole, trifloxystrobin + bixafen + prothioconazole, azoxystrobin + benzovindiflupyr, and azoxystrobin + benzovindiflupyr + diphenoconazole were highly fungitoxic for the majority of the isolates, with EC50 lower than 1.0 mg L-1. Diphenoconazole, azoxystrobin, and fenpropimorph were considered moderately fungitoxic for nine of the twelve isolates, with EC50 between 1 and 10 mg L-1. The multisites mancozeb and copper oxychloride presented EC50 responses classified as low toxic for the twelve isolates and eight for chlorothalonil (EC50 between 10 mg L-1 and 50 mg L-1). Site-specific fungicides showed high-to-moderate fungitoxicity to P. pachyrhizi isolates, even as the multisites presented moderate-to-less toxic activity.

scholarly journals Asian soybean rust in Brazil: past, present, and future

2016 ◽  
Vol 51 (5) ◽  
pp. 407-421 ◽  
Author(s):  
Cláudia Vieira Godoy ◽  
Claudine Dinali Santos Seixas ◽  
Rafael Moreira Soares ◽  
Franscismar Correa Marcelino-Guimarães ◽  
Maurício Conrado Meyer ◽  
...  
Keyword(s):  
Severe Disease ◽  
Management Strategies ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Yield Losses ◽  
Current Management ◽  
Asian Soybean Rust ◽  
Regulatory Measures ◽  
Major Resistance Genes ◽  
Crop System

Abstract: Asian soybean rust, caused by the fungus Phakopsora pachyrhizi, is the most severe disease of the crop and can cause yield losses of up to 90%. The disease was first reported in Brazil in 2001. Epidemics of the disease are common in the country, where the fungus can survive year-round. Regulatory measures to reduce the inoculum between seasons and avoid late-season soybean have been adopted to manage the disease. Disease control has relied mainly on chemical control, but a lower sensibility of the fungus to fungicides has been reported in Brazil. Major-resistance genes have been mapped and incorporated into the cultivars. With the reduced efficacy of the fungicides, the adoption of integrated measures to control the disease will be important for the sustainability of the crop. This review presents the main changes in the soybean crop system caused by the introduction of the fungus in Brazil, the current management strategies adopted to avoid losses, and the new trends that, together with biotechnological strategies, can improve management in the future.

scholarly journals Effects of Shade Intensity and Duration on Asian Soybean Rust Caused by Phakopsora pachyrhizi

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 485-489 ◽  
Author(s):  
A. P. S. Dias ◽  
X. Li ◽  
P. F. Harmon ◽  
C. L. Harmon ◽  
X. B. Yang
Keyword(s):  
Disease Incidence ◽  
Field Studies ◽  
Germination Percentage ◽  
Soybean Rust ◽  
Disease Development ◽  
Phakopsora Pachyrhizi ◽  
Asian Soybean Rust ◽  
Soybean Plants ◽  
Germ Tubes

Field studies to quantify the effects of shade intensity and duration on soybean rust caused by Phakopsora pachyrhizi were carried out in Florida in 2006 and 2007. Soybean plants at the V4 stage were inoculated with urediniospores at 2100, 0000, and 0200 h. Inoculated plants were either placed in cages that were covered with shade cloths of different mesh sizes allowing 70, 50, or 20% transmission of sunlight or were not covered so that the plants received 100% of sunlight. Plants kept under 20 and 100% sunlight were sampled 12, 18, and 36 h after inoculation to determine the in vivo germination percentage of urediniospores and the percentage of germ tubes that formed appressoria. In separate experiments, inoculated plants were placed under the shade (20% sunlight) and moved to unshaded conditions after 1, 2, and 7 days. For all experiments, soybean rust incidence and severity were rated 12 days after inoculation. Higher levels of disease incidence and severity were detected in plants under shade compared with those under full sunlight. Shade duration greater than 2 days favored disease development. Within 36 h, in vivo germination of urediniospores and formation of appressoria were not significantly affected by the treatments. These results may explain why soybean rust is more severe in the lower canopy and shaded areas in the field.

scholarly journals Transcriptome analyses and virus induced gene silencing identify genes in the Rpp4-mediated Asian soybean rust resistance pathway

2013 ◽  
Vol 40 (10) ◽  
pp. 1029 ◽  
Author(s):  
Aguida M. A. P. Morales ◽  
Jamie A. O'Rourke ◽  
Martijn van de Mortel ◽  
Katherine T. Scheider ◽  
Timothy J. Bancroft ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Gene Silencing ◽  
Differentially Expressed ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
R Gene ◽  
Virus Induced Gene Silencing ◽  
Asian Soybean Rust ◽  
Defence Responses

Rpp4 (Resistance to Phakopsora pachyrhizi 4) confers resistance to Phakopsora pachyrhizi Sydow, the causal agent of Asian soybean rust (ASR). By combining expression profiling and virus induced gene silencing (VIGS), we are developing a genetic framework for Rpp4-mediated resistance. We measured gene expression in mock-inoculated and P. pachyrhizi-infected leaves of resistant soybean accession PI459025B (Rpp4) and the susceptible cultivar (Williams 82) across a 12-day time course. Unexpectedly, two biphasic responses were identified. In the incompatible reaction, genes induced at 12 h after infection (hai) were not differentially expressed at 24 hai, but were induced at 72 hai. In contrast, genes repressed at 12 hai were not differentially expressed from 24 to 144 hai, but were repressed 216 hai and later. To differentiate between basal and resistance-gene (R-gene) mediated defence responses, we compared gene expression in Rpp4-silenced and empty vector-treated PI459025B plants 14 days after infection (dai) with P. pachyrhizi. This identified genes, including transcription factors, whose differential expression is dependent upon Rpp4. To identify differentially expressed genes conserved across multiple P. pachyrhizi resistance pathways, Rpp4 expression datasets were compared with microarray data previously generated for Rpp2 and Rpp3-mediated defence responses. Fourteen transcription factors common to all resistant and susceptible responses were identified, as well as fourteen transcription factors unique to R-gene-mediated resistance responses. These genes are targets for future P. pachyrhizi resistance research.

scholarly journals Resistance to Asian soybean rust in soybean lines with the pyramided three Rpp genes

2013 ◽  
Vol 13 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Naoki Yamanaka ◽  
Noelle G Lemos ◽  
Miori Uno ◽  
Hajime Akamatsu ◽  
Yuichi Yamaoka ◽  
...  
Keyword(s):  
Genetic Background ◽  
Susceptible Variety ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Soybean Line ◽  
Pathogen Population ◽  
Resistance Level ◽  
Asian Soybean Rust ◽  
High Level

In this study, the influence of genetic background on the resistance level of a soybean line carrying Rpp2, Rpp4, and Rpp5 was evaluated by backcrossing it with a susceptible variety. It was also evaluated eight lines which carry these Rpp genes against five Asian soybean rust (ASR) isolates, in order to determine the likely range of resistance against ASR isolates differing in pathogenicity. The results indicated that a high level of resistance against various ASR isolates could be retained in lines carrying the three Rpp genes in susceptible genetic backgrounds, although minor influences of plant genetic background and ASR pathogenicity to the ASR resistance could occur. Thus, lines with the pyramided three Rpp genes should be effective against a complex pathogen population consisting of diverse Phakopsora pachyrhizi isolates.

scholarly journals Characterization of three soybean landraces resistant to Asian soybean rust disease

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
Luciano Nobuhiro Aoyagi ◽  
Yukie Muraki ◽  
Naoki Yamanaka
Keyword(s):  
Susceptible Variety ◽  
Soybean Rust ◽  
Resistance Locus ◽  
Chromosome 6 ◽  
Phakopsora Pachyrhizi ◽  
Rust Disease ◽  
Asian Soybean Rust ◽  
The World ◽  
Trait Locus

Abstract Phakopsora pachyrhizi is an obligatory biotrophic fungus that causes Asian soybean rust (ASR) disease. ASR control primarily involves chemical control and the use of resistant soybean cultivars carrying an Rpp (resistance to P. pachyrhizi) gene. This study aimed to characterize the ASR resistance of three soybean Asian landraces. By screening the world core collection (WC) of soybean, which consists of 80 varieties, three landraces were identified in Southeast Asia as resistant to ASR. Genetic mapping using the F2 population derived from a cross with an ASR-susceptible variety, BRS 184, indicated that KS 1034 (WC2) has ASR resistance conferred by a single dominant resistance gene, mapped on chromosome 18, in the same region where Rpp1 was mapped previously. The BRS 184 × WC61 (COL/THAI/1986/THAI-80) F2 population, on the other hand, showed an ASR resistance locus mapped by quantitative trait locus analysis on chromosome 6, in the region where the resistance conferred by PI 416764 Rpp3 resides, with a logarithm of the odds score peak at the same position as the marker, Satt079, while the BRS 184 × WC51 (HM 39) population showed the resistance to ASR allocated between Satt079 and Sat_263 markers, also in the region where Rpp3 was mapped previously. Both WC51 and WC61 have the same infection profile as FT-2 and PI 462312 when tested against the same ASR isolate panel. These three WCs can be used in MAS programs for introgression of Rpp1 and Rpp3 and the development of ASR-resistant cultivars in the breeding program.

scholarly journals Models and applications for risk assessment and prediction of Asian soybean rust epidemics

2006 ◽  
Vol 31 (6) ◽  
pp. 533-544 ◽  
Author(s):  
Emerson M. Del Ponte ◽  
Cláudia V. Godoy ◽  
Marcelo G. Canteri ◽  
Erlei M. Reis ◽  
X.B. Yang
Keyword(s):  
Disease Modeling ◽  
Weather Conditions ◽  
Epidemiological Studies ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Spatial And Temporal Scales ◽  
Asian Soybean Rust ◽  
New Development ◽  
Glycine Max L ◽  
Favorable Weather

Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed.

Asian soybean rust: a scientometric approach of Phakopsora pachyrhizi studies

Euphytica ◽  
2020 ◽  
Vol 216 (8) ◽  
Author(s):  
Daniela Meira ◽  
Leomar Guilherme Woyann ◽  
Antonio Henrique Bozi ◽  
Anderson Simionato Milioli ◽  
Eduardo Beche ◽  
...  
Keyword(s):  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Asian Soybean Rust

scholarly journals Identifying Soybean Rust-resistant and Susceptible Populations of Kudzu to Increase Disease Monitoring Efficiency in Alabama

2016 ◽  
Vol 17 (4) ◽  
pp. 239-244 ◽  
Author(s):  
Edward J. Sikora ◽  
Mary A. Delaney
Keyword(s):  
Monitoring Program ◽  
Soybean Rust ◽  
Disease Monitoring ◽  
Phakopsora Pachyrhizi ◽  
Yield Losses ◽  
Early Disease ◽  
Soybean Production ◽  
Early Disease Detection ◽  
Significant Yield ◽  
Susceptible Populations

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is considered to be one of the most damaging diseases of soybean worldwide. Monitoring for the disease in Alabama relies heavily on scouting kudzu on a biweekly basis in south and central portions of the state from late January through the end of July in areas where soybean production is minimal and is critical to help growers avoid significant yield losses from SBR. Previous studies have reported that some kudzu populations are naturally resistant or immune to infection from the pathogen which can complicate early disease detection. This study will apply that knowledge to determine locations of kudzu populations that are either resistant or susceptible to P. pachyrhizi in order to increase monitoring efficiency and reduce costs associated with the scouting program. Results show that approximately 34% of the 162 kudzu sites tested in Alabama were resistant to P. pachyrhizi. By focusing scouting efforts on SBR-susceptible kudzu sites, we will reduce costs associated with the monitoring program by approximately 25% which is critical at a time when funding for such efforts is decreasing. Accepted for publication 24 October 2016.

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