Accuracy, Precision, and Correlation to Yield Loss of Disease Severity Scales for Corky Root of Lettuce

O’Brien, R. Douglas

doi:10.1094/phyto-82-91

Cited by 48 publications

(36 citation statements)

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“…The BAPB 1-9 scale is ordinal, but corresponds to percentages of a continuous variable, disease severity. O'Brien and van Bruggen [1992] analyse untransformed ordinal scores and percentages while Forbes and Jeger [1987] found that a logit No infection observed 3 colonies per tiller 5 colonies per leaf Lower leaves appear 1/4 infected Lower leaves appear 1/2 infected Leaves appear 1/2 infected 1/2 green Leaves appear more infected than green Very little green leaf tissue left Leaves dead -no green leaf left…”

Section: Field Experimentsmentioning

confidence: 99%

“…Hau et al [1989] found that inexperienced scorers are less accurate using a completely quantitative scale than using disease classes, but suggested that experienced scorers might be able to use a quantitative scale. O'Brien and van Bruggen [1992] compared two ordinal scales with a Horsfall-Barratt scale for assessing corky root of lettuce and found that no single scale was the best in all situations.…”

Section: Introductionmentioning

confidence: 99%

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Subjective components of mildew assessment on spring barley

Newton¹,

Hackett²

1994

Eur J Plant Pathol

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The severity of mildew on barley is usually assessed visually and this leads to variation between different scorers. Field assessments by four assessors were analysed to determine the nature and degree of subjective discrepancies between assessors. Two inexperienced assessors failed to detect a major effect of nitrogen due to differences in the interpretation of a scoring system. A computer-based training programme was evaluated for standardising assessments, and was found to improve assessors' accuracy. Linear regression analysis was used here to resolve the error variance into components representing the accuracy and precision of the assessors. Plots of the cumulative differences between the estimate of disease severity by each assessor and the best estimate were used to display how the discrepancies varied with the level of disease. Some modifications to the barley field scoring system are suggested to improve comparability between assessors.

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Section: Field Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Subjective components of mildew assessment on spring barley

Newton¹,

Hackett²

1994

Eur J Plant Pathol

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show abstract

“…In addition, measuring disease by visual rating lacked precision and accuracy. As revealed by O'Brien and Van Bruggen [36], the inaccuracies made while measuring disease in the field are a major constraint, when relating disease to yield, and in some cases, there may be no relationship between these two variables. Similar studies by Waggoner and Berger [37], Gaunt [34] and Filho et al [38] have indicated that the measurement of disease severity, based on lesion number or leaf area, may be less related to yield.…”

Section: Discussionmentioning

confidence: 99%

Genotypic Response of Dry Bean (Phaseolus vulgaris L.) to Natural Field Infection of Ascochyta Blight (Phoma exigua var. diversispora (Bubak) Boerema) under Diverse Environmental Conditions in Rwanda

2017

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Ascochyta blight, caused by Phoma exigua var. diversispora (Bubak) Boerema, is a serious constraint in the cultivation of the common bean (Phaseolus vulgaris L.) in Rwanda, particularly in the cool and wet highland production areas. In order to identify resistant genotypes, a germplasm evaluation study was conducted to quantify the impact of the disease on phenotypic and agronomic traits under natural conditions. Field screening trials of 39 bush (Types I, II and III) and 36 climbing (Type IV) genotypes from different accessions within and outside the country were conducted at three sites, namely, Rwerere, Nyamagabe and Musanze Research Stations, for two seasons. The relative area under the disease progress curve (RAUDPC) based on evaluations of the disease severity (percentage leaf area infected), was used to evaluate the genotypes. Thirteen genotypes were identified with some level of ascochyta resistance. The study revealed Rwandan genotypes G 2333 and SMC 18 as new sources of resistance to Ascochyta blight. Additional results showed a negative relationship (r = −0.42 and −0.51 for Seasons A and B, respectively) between ascochyta infection and yield. Further relationships were identified between the plant flower colour and seed size to ascochyta resistance. Some of the identified resistant genotypes can be used to introgress ascochyta resistance into susceptible Rwandan market classes of common bean genotypes.

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“…A partir dessa escala, vários outros diagramas foram desenvolvidos, por exemplo, para a cultura do feijão (DÍAZ et al, 2001), inhame (MICHEREFF et al, 2000), citrus (SPÓSITO et al, 2004), tomate (BOFF et al, 1991), abacaxi (ROHRBACH e SCHIMITT, 1994), alface (O' BRIEN e VAN BRUGGEN, 1992), cereais (DUVEILLER, 1994), soja (MARTINS et al, 2004), eucalipto (ANDRADE et al, 2005), entre outras.…”

Section: Introductionunclassified

Procedimento estatístico para validação de escalas diagramáticas na quantificação de doenças

Máfia¹,

Ferreira

Binoti

et al. 2011

Rev. Árvore

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RESUMO -Na validação de escalas diagramáticas de doenças é comum utilizar a regressão linear simples para testar a identidade entre dados estimados e valores reais de severidade de doença. Nestes casos, após ajustar a regressão linear, as hipóteses H01: β 0 = 0 e H02: β 1 = 1 ão testadas, mas não de forma simultânea, ou seja, se β 0 = 0 ao mesmo tempo em que β 1 = 1, ou, se β 1 = 1 ao mesmo tempo em que β 0 = 0. O objetivo deste trabalho foi propor um novo procedimento estatístico para validação de escalas diagramáticas, denominado L&O. Este procedimento resulta da combinação do teste F, modificado por Graybill (1976), teste t para o erro médio e análises do coeficiente de correlação linear. Este procedimento foi aplicado para testar a identidade entre valores estimados e valores reais de severidade da doença causada por Quambalaria eucalypti em eucalipto. Os resultados mostraram que o procedimento estatístico foi eficiente, não subjetivo e permitiu também testar a identidade entre quaisquer dois vetores ou grupos de dados quantitativos. STATISTICAL PROCEDURE FOR VALIDATION OF DIAGRAMMATIC SCALES TO DISEASE QUANTIFICATION ABSTRACT -Validation of disease diagrammatic scale is commonly done by using simple linear regression to test the identity between estimates and observed values of disease severity . In this case, when adjusting a linear regression, only evaluation of the hypotheses

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Accuracy, Precision, and Correlation to Yield Loss of Disease Severity Scales for Corky Root of Lettuce

Cited by 48 publications

References 0 publications

Subjective components of mildew assessment on spring barley

Subjective components of mildew assessment on spring barley

Genotypic Response of Dry Bean (Phaseolus vulgaris L.) to Natural Field Infection of Ascochyta Blight (Phoma exigua var. diversispora (Bubak) Boerema) under Diverse Environmental Conditions in Rwanda

Procedimento estatístico para validação de escalas diagramáticas na quantificação de doenças

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