Comparação de dois métodos de elaboração e validação de escala diagramática para a quantificação da severidade da mancha de Cylindrocladium em eucalipto

Damasceno, Vítor Flávio Furtado; Furtado, Edson Luiz; Filho, Pedro Berci

doi:10.1590/0100-5405/1960

Cited by 8 publications

(6 citation statements)

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“…These scales are subjective, not permitting the visual acuity adjustment in assessing severity levels (Campbell & Madden, 1990), impairing the accurate quantification of the injured area (Santos et al, 2017). On the other hand, diagrammatic scales or standard area diagram sets (SADs) not only improve the accuracy and the precision of disease evaluations, but also demonstrate significant improvements in the visual estimates of severity (Damasceno et al, 2014;De Paula et al, 2016;Santos et al, 2017). Thus, they are valuable tools in breeding programs, whose success is achieved depending on the exact and accurate use of quantification methods of disease severity and selection of resistant materials (Librelon et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Standard area diagram set for quantification of septoriosis in fruit of sour passion fruit

Costa¹,

Peixoto²,

Blum³

et al. 2019

Agraria

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A standard area diagram set (SADs) for severity evaluation of septoriosis (Septoria passiflorae) in fruit of sour passion fruit (Passiflora edulis Sims) was developed and validated in this study. The SADs presented eight severity levels (0.3; 0.5; 1; 2; 4; 10; 18; and 30%). For its validation, 20 raters were divided into groups (G1 and G3, inexperienced; G2 and G4, experienced) who initially estimated the disease severity without the aid of the SADs. Subsequently, G1 and G2 performed the second evaluation without the SADs, and G3 and G4 completed the second evaluation with the proposed SADs for each disease. The accuracy and precision of the evaluations were determined by simple linear regression and by Lin's concordance correlation coefficient. The proposed SADs allowed accurate and precise quantification of septoriosis severity, increasing the agreement between estimated and actual values. The increase in accuracy and precision in the non-aided groups, when present, was less pronounced than those increments observed in the SADs-aided groups. Lin's concordance correlation coefficient confirmed the increases in accuracy and precision detected by the linear regression analysis.Escala diagramática para a quantificação da severidade da septoriose em frutos do maracujazeiro azedo RESUMO: Uma escala diagramática para a avaliação da severidade da septoriose (Septoria passiflorae) em frutos do maracujazeiro azedo (Passiflora edulis Sims) foi desenvolvida e validada neste estudo. A escala diagramática apresentou oito níveis de severidade (0,3; 0,5; 1; 2; 4; 10; 18; e 30%). Para a sua validação, os 20 avaliadores foram divididos em grupos (G1 e G3, sem experiência; G2 e G4, com experiência), que inicialmente estimaram a severidade da doença sem auxílio da escala. Posteriormente, G1 e G2 fizeram outra avaliação sem escala, e G3 e G4 realizaram a avaliação com a escala proposta. A acurácia e a precisão das estimativas foram determinadas por regressão linear simples e pelo coeficiente de correlação de concordância de Lin. A escala diagramática proposta permitiu quantificar a severidade da septoriose de forma acurada e precisa, aumentando a concordância entre os valores estimados e os reais. O aumento da acurácia e precisão nos grupos que realizaram dupla avaliação sem escala, quando ocorreu, foi mais discreto que os incrementos observados nos grupos que utilizaram a escala. A análise de concordância de Lin confirmou os incrementos da acurácia e precisão detectados pela análise de regressão linear. Palavras-chave: frutos; Passiflora edulis Sims; fitopatometria; Septoria passifloraeStandard area diagram set for quantification of septoriosis in fruit of sour passion fruit Rev. Bras.

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Section: Introductionmentioning

confidence: 99%

Standard area diagram set for quantification of septoriosis in fruit of sour passion fruit

Costa¹,

Peixoto²,

Blum³

et al. 2019

Agraria

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“…() and rating blight symptoms with the diagrammatic scale developed by Damasceno et al . (). Nonetheless, both methods were found to be influenced by defoliation (either natural or resulting from infection) occurring in the eucalypt plants.…”

Section: Discussionmentioning

confidence: 99%

“…In this work, aggressiveness was evaluated weekly up to 35 dai, both assessing plant defoliation by the method of Grac ßa et al (2009) and rating blight symptoms with the diagrammatic scale developed by Damasceno et al (2014). Nonetheless, both methods were found to be influenced by defoliation (either natural or resulting from infection) occurring in the eucalypt plants.…”

Section: Discussionmentioning

confidence: 99%

“…Prior to inoculation, the number of leaves of four branches marked on the basal third of each plant was counted. Disease severity was assessed by rating blight symptoms with a diagrammatic scale (Damasceno et al ., ) and estimating the percentage of plant defoliation. In assessing blight symptoms, scores were assigned to the five most severely diseased leaves of each plant.…”

Section: Methodsmentioning

confidence: 99%

“…Measures of disease severity caused by selected Calonectria pteridis Median disease severity score measured using a diagrammatic scale(Damasceno et al, 2014) at 7 dai. Medians within each row of disease severity scores followed by the same lowercase letter are not significantly different according to the t-test for nonparametric distributions (P ≤ 0.05).…”

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Genetic diversity and aggressiveness of Calonectria pteridis in Eucalyptus spp.

et al. 2019

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Calonectria leaf blight, caused by Calonectria pteridis, is currently one of the main foliar diseases in eucalypt plantations in Brazil. In warm and high rainfall regions, the disease can be a limiting factor for eucalypt production when planting susceptible genotypes. The most effective method for controlling this disease in the field is the use of resistant genotypes, which requires knowledge of the genetic variability and aggressiveness of the pathogen population for effective deployment of plant resistance. This work evaluated the genetic diversity and aggressiveness of C. pteridis populations obtained from infected eucalypt plants in Monte Dourado (Pará state) and Imperatriz (Maranhão state), Brazil. To study the genetic diversity, 16 ISSR primers were tested, five of which amplified polymorphic, reproducible and informative bands. Thirty‐one closely related genotypes were identified from 84 isolates studied, indicating that the population has a low genetic diversity. The aggressiveness of seven isolates, selected according to geographic origin and their clustering in the ISSR‐based dendogram, was determined by inoculation of a hybrid Eucalyptus grandis × E. urophylla clone under controlled conditions. Disease severity was assessed by both measuring the percentage of plant defoliation and assigning a score according to a diagrammatic scale of symptoms. A high correlation between the two evaluation methods was observed, which revealed significant differences in aggressiveness among the isolates. The diagrammatic scale is recommended for disease evaluation because results are obtained much faster, before the occurrence of severe defoliation. No correlation between clustering in the ISSR‐based phylogenetic analysis and aggressiveness was observed.

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