scholarly journals Diagrammatic scale for assessment the severity of Cercospora leaf blight on soybean (Glycine max) leaflets

2021 ◽  
pp. 43338
Author(s):  
Miguel Lavilla ◽  
Antonio Ivancovich ◽  
Antonio Díaz-Paleo
Keyword(s):  
Glycine Max ◽  
Leaf Blight ◽  
Visual Interpretation ◽  
Cercospora Kikuchii ◽  
Stimulus Response ◽  
Population Average ◽  
Crop Disease ◽  
Severity Levels ◽  
Foliar Fungicide ◽  
Diagrammatic Scale

Introduction. Cercospora leaf blight (CLB) caused by Cercospora kikuchii is an endemic soybean crop disease in Argentina. Objective. To develop and validate a scale to quantify the severity of CLB in leaflets of soybean (Glycine max) for the evaluation of foliar fungicides and cultivar trials. Materials and methods. A diagrammatic scale to assess the severity of CLB on soybean leaflets (Glycine max) was developed. The scale was based on the evaluation of 50 leaflets. The different severity levels of the leaflets were determined according to Weber-Fechner’s stimulus-response law. The proposed scale included severity levels of 1, 4.5, 17.5, 50, 82.2, 95, and 99 %. The validation of the scale was performed by 23 raters (3 experienced and 20 inexperienced) who assessed the severity of CLB on 50 leaflets with and without the use of the scale. Results. The results from the three experienced raters were more precise than those obtained by the inexperienced raters. The scale improved the visual interpretation to assess the severity of CLB for the inexperienced raters, who obtained estimated severity values close to the actual severity values. When the inexperienced raters used the proposed scale to estimate the severity of CLB on leaflets, they were accurate having determination coefficients (R2) between 0.74 and 0.91. According to the absolute errors, the greatest deviation was observed between -2.49 and 2.46. However, these deviations were not significantly different from the population average. To speed the process of cultivar evaluations we also propose the use of scales based on grades. Conclusions. The proposed scale to assess the severity of CLB on leaflets can be used for the assessment of foliar fungicide trials and soybean cultivars. The scale showed specificity for assessing the severity of Cercospora leaf blight (CFB) in soybean leaflets.

scholarly journals Diagrammatic scale for assessment of soybean rust severity

2006 ◽  
Vol 31 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Cláudia V. Godoy ◽  
Lucimara J. Koga ◽  
Marcelo G. Canteri
Keyword(s):  
Glycine Max ◽  
Scale Validation ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Stimulus Response ◽  
Accuracy And Precision ◽  
Rust Severity ◽  
Severity Levels ◽  
Diagrammatic Scale

A diagrammatic scale to assess soybean (Glycine max) rust severity, caused by the fungus Phakopsora pachyrhizi, was developed in this study. Leaflets showing different severity levels were collected for determination of the minimum and maximum severity limits; intermediate levels were determined according to "Weber-Fechner's stimulus-response law". The proposed scale showed the levels of 0.6; 2; 7; 18; 42, and 78.5%. Scale validation was performed by eight raters (four inexperienced and four experienced), who estimated the severity of 44 soybean leaflets showing rust symptoms, with and without the use of the scale. Except for rater number eight, all showed a tendency to overestimate severity without the aid of the diagrammatic scale. With the scale, the raters obtained better accuracy and precision levels, although the tendency to overestimate was maintained. Experienced raters were more accurate and precise than inexperienced raters, and assessment improvements with the use of the scale were more significant for inexperienced raters.

scholarly journals Development and validation of a diagrammatic scale for quantifying maize leaf spots caused by Diplodia macrospora

2019 ◽  
Vol 40 (6) ◽  
pp. 2475
Author(s):  
Eloisa Lorenzetti ◽  
Juliano Tartaro ◽  
Alfredo José Alves Neto ◽  
Anderson Luis Heling ◽  
Jeferson Carlos Carvalho ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Disease Severity ◽  
Maize Leaf ◽  
Stimulus Response ◽  
Severity Of Disease ◽  
Leaf Spots ◽  
Maize Leaves ◽  
Severity Levels ◽  
Development And Validation ◽  
Diagrammatic Scale

The objective of this study was to develop and validate a diagrammatic scale to evaluate the severity of spots on maize leaves caused by the fungus Diplodia macrospora. Severity ranged between the minimal (0.5%) and maximal (55%) limits of disease severity, and intermediate severity levels were defined according to the "Weber-Fechner stimulus response law". The proposed scale describes six levels of severity based on how much of the leaf is affected: 0.5%, 3%, 8%, 23%, 36%, and 55%. Validation was carried out by eight evaluators, four inexperienced and four experienced. They estimated the severity of disease in 60 maize leaves, with and without the proposed diagrammatic scale. A relationship was shown by regression analysis between estimated and actual severity, with and without the use of the scale. When both inexperienced and experienced evaluators used the scale, they were able to estimate disease severity more accurately and precisely.

scholarly journals Diagrammatic scale for assessment of anthracnose severity in feijoa fruit

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Ana Carolina Ferreira ◽  
Idemir Citadin ◽  
Silvia Scariotto ◽  
Rafael Henrique Pertille ◽  
Marcos Robson Sachet ◽  
...  
Keyword(s):  
Disease Severity ◽  
Stimulus Response ◽  
Severity Levels ◽  
Diagrammatic Scale ◽  
Fruit Surface

ABSTRACT: A diagrammatic scale of anthracnose in feijoa fruit was elaborated and validated in order to standardize disease severity assessments. The proposed scale showed six disease severity levels: 2, 10, 20, 40, 70 and 100% of the injured fruit surface. The scale took into account the minimum and maximum limits of disease severity observed in the field and the intermediate values followed logarithmic increments according to the Weber-Fechner stimulus-response law. Eight inexperienced raters validated the scale by quantifying the disease severity (using/not using the scale) of 50 feijoas with anthracnose symptoms. In conclusion, the scale improved the assessment of anthracnose in feijoa. Eight genotypes from different crosses were tolerant to anthracnose.

scholarly journals Diagrammatic scale to assess downy mildew severity in melon

2009 ◽  
Vol 27 (1) ◽  
pp. 76-79 ◽  
Author(s):  
Sami J Michereff ◽  
Marissônia A Noronha ◽  
Gaus SA Lima ◽  
Ígor CL Albert ◽  
Edilaine A Melo ◽  
...  
Keyword(s):  
Linear Regression ◽  
Leaf Area ◽  
Downy Mildew ◽  
Pseudoperonospora Cubensis ◽  
Northeast Brazil ◽  
Simple Linear Regression ◽  
Standard Methods ◽  
Accuracy And Precision ◽  
Severity Levels ◽  
Diagrammatic Scale

The downy mildew, caused by Pseudoperonospora cubensis, is an important melon disease in Northeast Brazil. Considering the lack of standard methods for its assessment, a diagrammatic scale was developed with 2, 4, 8, 16, 32, 64, 82, and 96% of affected leaf area. The scale was then checked for its accuracy, precision, and reproducibility in estimating downy mildew severity. The diagrammatic scale was validated by eight disease raters; using 50 leaves with different severity levels, previously measured using the software Assess®. Two evaluations were performed on the same set of leaves, but in a different sequence order, by the same raters, within a 15-day interval. The accuracy and precision of each rater was determined by simple linear regression between the actual and the estimated severity. The scale provided good levels of accuracy (means of 87.5%) and excellent levels of precision (means of 94%), with absolute errors concentrated around 10%. Raters showed great repeatability (means of 94%) and reproducibility (>90% in 90.3% of cases) of estimates. Therefore, we could conclude that the diagrammatic scale presented here was suitable for evaluating downy mildew severity in melon.

scholarly journals Correction: Zhao, H., et al. Automatic Estimation of Crop Disease Severity Levels Based on Vegetation Index Normalization. Remote Sensing 2020, 12, 1930

2020 ◽  
Vol 12 (22) ◽  
pp. 3761
Author(s):  
Hengqian Zhao ◽  
Chenghai Yang ◽  
Wei Guo ◽  
Lifu Zhang ◽  
Dongyan Zhang
Keyword(s):  
Remote Sensing ◽  
Disease Severity ◽  
Vegetation Index ◽  
Automatic Estimation ◽  
Crop Disease ◽  
Severity Levels

The authors wish to make the following correction to this paper [...]

scholarly journals Fungicide Resistance in Cercospora kikuchii, a Soybean Pathogen

Plant Disease ◽  
2015 ◽  
Vol 99 (11) ◽  
pp. 1596-1603 ◽  
Author(s):  
Paul P. Price ◽  
Myra A. Purvis ◽  
Guohong Cai ◽  
Guy B. Padgett ◽  
Clark L. Robertson ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Radial Growth ◽  
Management Strategies ◽  
Leaf Blight ◽  
Cross Resistance ◽  
Multiple Resistance ◽  
Cercospora Kikuchii ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Purple Seed Stain

Isolates of Cercospora kikuchii, a soybean (Glycine max) pathogen causing Cercospora leaf blight and purple seed stain, were tested to determine baseline sensitivities (n = 50) to selected quinone outside inhibitor (QoI) fungicides by conducting radial growth assays on fungicide-amended media. Baseline effective fungicide concentration to inhibit 50% of fungal radial growth (EC50) values were compared with EC50 values for isolates collected in 2011 (n = 50), 2012 (n = 50), and 2013 (n = 36) throughout soybean-producing areas in Louisiana. Median EC50 values for isolates subjected to QoI fungicides were significantly (P = 0.05) higher across all 3 years. Cross-resistance to QoI fungicides was observed in resistant isolates collected in 2011 to 2013. Discriminatory doses were developed for QoI fungicides to distinguish between sensitive and resistant isolates. On average, 89% of all isolates screened in 2011 to 2013 were resistant to QoI fungicides. At a discriminatory dose of thiophanate methyl (TM), a methyl benzimidazole carbamate (MBC) fungicide, at 5 μg/ml, resistance was detected in the 2000, 2011, 2012, and 2013 collections at 23, 38, 29, and 36%, respectively. Isolates exhibiting multiple resistance to QoI fungicides and TM also were detected in 2011, 2012, and 2013 at frequencies of 34, 26, and 31%, respectively. Based on these results, Cercospora leaf blight management strategies in Louisiana using solo applications of QoI or MBC fungicides in soybean should be reconsidered.

scholarly journals Validation of a diagrammatic scale for quantification of bacterial leaf blight (causal agent Pseudomonas avenae) in maize

2020 ◽  
Vol 41 (6) ◽  
pp. 2467-2480
Author(s):  
Eloisa Lorenzett ◽  
◽  
Juliano Tartaro ◽  
José Renato Stangarlin ◽  
Roberto Luis Portz ◽  
...  
Keyword(s):  
Visual Stimulus ◽  
Leaf Blight ◽  
Bacterial Leaf Blight ◽  
Economic Damage ◽  
Severity Assessment ◽  
Total Leaf Area ◽  
Accuracy And Precision ◽  
Injured Area ◽  
Different Levels ◽  
Diagrammatic Scale

Bacterial leaf blight occurs in almost the entire Brazilian territory and can cause significant economic damage. However, its effects can be curtailed with the following tools that aid in quantification for carrying out the best severity assessment that can be applied to the studies used in its control. The objective of this study was to develop and validate a diagrammatic scale to quantify the severity of bacterial leaf blight in maize caused by Pseudomonas avenae. Corn leaves were collected with different levels of disease severity, and the total leaf area as well as the injured area of the middle third of each leaf was measured. From this, the minimum and maximum limits of the disease and, subsequently, four intermediate levels were determined whilst taking into account the law of visual stimulus of Weber-Fechner. Levels 1.5%, 2.5%, 9%, 18%, 46%, and 70% were selected with validation performed by eight evaluators, four inexperienced and four experienced. These evaluators estimated the severity values, initially without the use of the proposed diagrammatic scale and in a second attempt with the use of the scale. We concluded that it was possible to improve the accuracy and precision of the evaluators when they used the scale as a tool to assess the severity of bacterial leaf blight on corn leaves.

Morphological discrimination among some aneuploids in soybean (Glycine max (L.) Merr.). I. Trisomies

1985 ◽  
Vol 27 (5) ◽  
pp. 608-613 ◽  
Author(s):  
J. Jefferson Gwyn ◽  
R. G. Palmer ◽  
K. Sadanaga
Keyword(s):  
Glycine Max ◽  
Discriminant Analysis ◽  
Root Tip ◽  
Phenotypic Traits ◽  
Visual Interpretation ◽  
F Test ◽  
Significance Level ◽  
Phenotypic Differences ◽  
Glycine Max L

A study of the phenotypes of four primary trisomies (2n + 1) in soybean (Glycine max (L.) Merr.) was conducted. The purpose was to determine whether measurable and consistent phenotypic differences exist between these trisomics and their disomic sibs. These trisomics are designated Tri A, B, C, and D. These trisomic stocks are homozygous but are not isolines. Root-tip squashes of seedlings were used to identify all trisomic and disomic plants. Several plants of each different trisomic type along with an equal number of their disomic sibs were transplanted to the field and randomized within four separate rows. Nineteen different phenotypic traits were measured on all plants.Stepwise discriminant analysis was used to select variables that were good discriminators (0.10 significance level). Each of the four trisomic–disomic comparisons contained a different but overlapping subset of variables that were used in subsequent discriminant analysis. The first discriminatory variable was computed for each trisomic and disomic plant and plotted on a frequency bar chart. Visual interpretation of the chart, along with an F-test, indicates that these trisomics of soybean cannot be reliably distinguished from their disomic sibs on the basis of the phenotypic traits used in this study.Key words: soybean, trisomic, morphology.

scholarly journals Pathogenicity, molecular characterization, and cercosporin content of Brazilian isolates of Cercospora kikuchii

2005 ◽  
Vol 30 (6) ◽  
pp. 594-602 ◽  
Author(s):  
Álvaro M. R. Almeida ◽  
Fernanda F. Piuga ◽  
Silvana R. R. Marin ◽  
Eliseu Binneck ◽  
Fábio Sartori ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Glycine Max ◽  
Strong Correlation ◽  
Clustering Analysis ◽  
Rapd Analysis ◽  
Geographic Origin ◽  
Colony Growth ◽  
High Similarity ◽  
Cercospora Kikuchii ◽  
Geographic Regions

Cercospora kikuchii, involved with the defoliation of soybean (Glycine max) plants, is normally associated with Septoria glycines in late season. Seventy-two isolates from different regions in Brazil, obtained mainly from purple stained seeds, showed phenotypic variation. Cercosporin content and rate of colony growth was higly variable among isolates. A strong correlation between cercosporin content and virulence was identified. Genetic variation among and within populations was evaluated based on 86 RAPD loci. The RAPD analysis clustered all isolates into seven groups. No relationship was observed between RAPD groups and geographic origin or cercosporin content. The sequence of the internal spacer regions (ITS1-5.8S-ITS2) from 13 isolates chosen according to the previous RAPD and clustering analysis showed high similarity (97%-100%) to the GenBank sequences of C. kikuchii (AY266160, AY266161, AY152577 and AF291708). It is clear from this work that Brazilian isolates of C. kikuchii from different geographic regions, are variable in relation to virulence, RAPD profiles and cercosporin content. Cercosporin content could be a good parameter for choosing an adequate isolate for screening resistant or tolerant cultivars. Considering that this pathogen is easily seed-borne, findings are expected to show the same haplotypes in different regions. Migration could be favoured by infected seeds as demonstrated by RAPD analysis.

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