Diagrammatic scales for the estimation of black node disease severity in common bean / Escalas diagramáticas para a estimativa da gravidade da doença do nó negro no feijão comum

The objective of this study was to design two diagrammatic scales for the evaluation of black node disease (Stagonosporopsis hortensis and Boeremia spp.) in common bean (Phaseolus vulgaris L.). The developed scales corresponded to logarithmic intervals (SADL) of seven levels and equal intervals (SADE) of nine levels. These scales were compared to the scale developed by the International Center for Tropical Agriculture (CIAT), which corresponds to a descriptive scale (NoSAD). In the scale validation the accuracy, precision, and concordance of repeatability were determined using Lins concordance correlation coefficient, whereas inter-rater reproducibility was determined by the overall concordance correlation coefficient (OCCC). It was observed that with the use of the proposed scales, reproducibility and repeatability were significantly improved for inexperienced raters, and reproducibility was improved in the case of experienced raters. Thus, the designed standard area diagrams with equal and logarithmic intervals are a useful tool for estimating severity under field and experimental conditions as part of the study of this patho-system.(AU)

O objetivo deste estudo foi delinear duas escalas diagramáticas para avaliação da doença do nó preto (Stagonosporopsis hortensis e Boeremia spp.) em feijoeiro (Phaseolus vulgaris L.). As escalas desenvolvidas corresponderam a intervalos logarítmicos (SADL) de sete níveis e intervalos iguais (SADE) de nove níveis. Essas escalas foram comparadas com a escala desenvolvida pelo Centro Internacional de Agricultura Tropical (CIAT), que corresponde a uma escala descritiva (NoSAD). Na validação da escala, a exatidão, precisão e concordância da repetibilidade foram determinadas usando o coeficiente de correlação de concordância de Lin, enquanto a reprodutibilidade entre avaliadores foi determinada pelo coeficiente de correlação de concordância geral (OCCC). Observou-se que, com o uso das escalas propostas, a reprodutibilidade e a repetibilidade foram significativamente melhoradas para os avaliadores inexperientes, e a reprodutibilidade foi melhorada no caso dos avaliadores experientes. Assim, as escalas diagramáticas projetadas são uma ferramenta útil para estimar a severidade em condições experimentais e de campo como parte do estudo desse sistema patológico.(AU)

Standard area diagram set for scab quantification in trilobed leaves of the sour passion fruit / Escala diagramática para a quantificação da verrugose em folhas trilobadas do maracujazeiro azedo

The study aimed to develop and validate a standard area diagram set (SADs) to improve accuracy, precision, and reproducibility in the assessment of scab severity in trilobed leaves of the sour passion fruit. The SADs comprised six severity levels (1%; 3%; 6%; 11%; 21%; and 33%). The SADs increased the accuracy of the estimates by reducing the constant and systematic errors, and the tendency to overestimate the actual severity, limited the number of evaluators who presented this trend, in addition to increasing the bias correction factor. The inexperienced evaluators were the ones that benefited the most from the SADs use. Once the SADs was introduced, 80% and 100% evaluators gave estimates free from constant and systematic errors, respectively. The improvement in precision was verified by the increase in the coefficient of determination and Lins concordance correlation coefficient, by reducing absolute errors and increasing the reproducibility of the estimates.(AU)

O objetivo deste estudo foi desenvolver e validar uma escala diagramática para melhorar a acurácia, precisão e reprodutibilidade na avaliação da severidade da verrugose em folhas trilobadas do maracujazeiro azedo. A escala apresentou seis níveis de severidade (1; 3; 6; 11; 21 e 33%) e aumentou a acurácia das estimativas, reduzindo os erros constantes e sistemáticos, a tendência de superestimação em relação aos valores de severidade real e o número de avaliadores que apresentavam essa tendência, além de aumentar o fator de correção do desvio. Os avaliadores inexperientes foram os mais beneficiados pela utilização da escala, sendo que 80% e 100% destes avaliadores apresentaram estimativas livres de erros constantes e sistemáticos, respectivamente, quando a escala foi empregada. O aumento da precisão foi verificado pelo incremento dos coeficientes de determinação e de concordância de Lin, redução dos erros absolutos e aumento da reprodutibilidade das estimativas.(AU)

A diagramatic scale to quantify severity of antracnose in Rubus glaucus Benth / Uma escala diagramática para quantificar a severidade da antracnose em Rubus glaucus Benth

Rubus glaucus Benth, commonly referred to as mora de Castilla, is affected by Colletotrichum acutatum, as it induces anthracnose in many of the plant organs. Generally, it affects the fruits during the post-harvest phase and damages them, causing economic losses due to the poor crop quality. At present, no standardized methods are available for this pathosystem that can be used to characterize quantitatively the epidemic and to permit the prediction and comparison of the disease management techniques. In this research, we proposed a logarithmic diagrammatic scale of the severity of anthracnose induced by C. acutatum in the fruits of the thornless variety of R. glaucus Benth. This scale is constructed on the adjustment of the Weber-Fechner law and includes six classes, viz., 0%, 1-6%, 7-25%, 26-50%, 51-75%, 76-100%. The scale was validated using 14 evaluators, which entailed measuring the affected fruits with and without utilizing the scale; this improved the precision, accuracy and reproducibility of the calculations whenever the scale was used. We concluded that the scale proposed can be used to assess the severity of anthracnose induced by the fungus in the R. glaucus Benth fruits.(AU)

Mora de Castilla (Rubus glaucus Benth) é afetado por Colletotrichum acutatum, causando antracnose em órgãos diferentes da planta. Nos frutos geralmente é em pós-colheita, causando danos que geram perdas econômicas relacionadas com a qualidade das culturas. Ainda não existem para esse patossistema métodos padronizados para caracterizar quantitativamente a epidemia e que pode prever e comparar os métodos de manejo da doença. Por esta razão, neste trabalho foi criada uma escala logarítmica diagramática da severidade da antracnose causada pelo fungo C. acutatum em frutos de R. glaucus Benth com base na lei de Weber-Fechnere composto por 6 niveis: 0%, 1-6%, 7-25%, 26-50%, 51-75% e 76-100%. A escala foi validada por 14 evaluadores, fazendo medições de frutos afetados com e sem o uso da escala, que mostrou melhor precisão, exatitude e reproducibilidade nas avaliações em que o uso da escala foi feito. Isto permite concluir que a escala proposta pode ser usada na estimação da severidade da antracnose causada em frutos de R. glaucus Benth.(AU)

Standard area diagram set for olive leaf spot assessment / Escala diagramática para avaliação de repilo em oliveira

The establishment of olive (Olea europaea) orchards in Brazil is increasing due to their economic potential and benefits to human health. However, a number of limiting factors need to be overcome, such as Olive Leaf Spot (OLS) occurrence, for olives to reach their full potential. OLS, which is caused by Fusicladium oleaginum, results in defoliation and a reduction in fruit production. This study aimed to develop a standard area diagram set (SAD) for the assessment of OLS severity under humid subtropical climate conditions. The SAD was developed with six levels of severity (1, 3, 6, 9, 12 and 15%) and OLS severity was validated by eight inexperienced raters. Using the SAD provided an increase in accuracy, precision and concordance, while also reducing the smallest difference detectable. The proposed SAD was adequate at estimating the OLS and could be a useful tool for use in epidemiological and phytopathometry studies, evaluation of control strategies and selection of resistant genotypes.

O cultivo da oliveira (Olea europaea) no Brasil é crescente devido seu potencial econômico e pelos benefícios que seus produtos oferecem à saúde humana, entretanto, alguns fatores limitantes precisam ser superados, como a ocorrência do repilo (OLS). O repilo, causado pelo fungo Fusicladium oleagineum, causa desfolha e redução da produção de azeitonas. O objetivo deste trabalho foi elaborar uma escala diagramática para auxiliar nas estimativas de severidade de repilo em oliveira em condição de clima subtropical úmido. A escala diagramática foi elaborada com 6 níveis (1, 3, 6, 9, 12 e 15%) e validada por 8 avaliadores inexperientes. Com o uso da escala houve aumento na acurácia, precisão e concordância, também redução do menor valor de severidade detectável. A escala proposta foi adequada para estimar a severidade de repilo em oliveira, podendo ser utilizada para estudos epidemiológicos, avaliação de estratégias de controle e seleção de genótipos resistentes.

Standard area diagram set for olive leaf spot assessment / Escala diagramática para avaliação de repilo em oliveira

The establishment of olive (Olea europaea) orchards in Brazil is increasing due to their economic potential and benefits to human health. However, a number of limiting factors need to be overcome, such as Olive Leaf Spot (OLS) occurrence, for olives to reach their full potential. OLS, which is caused by Fusicladium oleaginum, results in defoliation and a reduction in fruit production. This study aimed to develop a standard area diagram set (SAD) for the assessment of OLS severity under humid subtropical climate conditions. The SAD was developed with six levels of severity (1, 3, 6, 9, 12 and 15%) and OLS severity was validated by eight inexperienced raters. Using the SAD provided an increase in accuracy, precision and concordance, while also reducing the smallest difference detectable. The proposed SAD was adequate at estimating the OLS and could be a useful tool for use in epidemiological and phytopathometry studies, evaluation of control strategies and selection of resistant genotypes.(AU)

O cultivo da oliveira (Olea europaea) no Brasil é crescente devido seu potencial econômico e pelos benefícios que seus produtos oferecem à saúde humana, entretanto, alguns fatores limitantes precisam ser superados, como a ocorrência do repilo (OLS). O repilo, causado pelo fungo Fusicladium oleagineum, causa desfolha e redução da produção de azeitonas. O objetivo deste trabalho foi elaborar uma escala diagramática para auxiliar nas estimativas de severidade de repilo em oliveira em condição de clima subtropical úmido. A escala diagramática foi elaborada com 6 níveis (1, 3, 6, 9, 12 e 15%) e validada por 8 avaliadores inexperientes. Com o uso da escala houve aumento na acurácia, precisão e concordância, também redução do menor valor de severidade detectável. A escala proposta foi adequada para estimar a severidade de repilo em oliveira, podendo ser utilizada para estudos epidemiológicos, avaliação de estratégias de controle e seleção de genótipos resistentes.(AU)

Comparative analysis for quantification of Citrus Variegated Chlorosis in the field

Citrus Variegated Chlorosis (CVC) caused by Xylella fastidiosa is one of the most important diseases for Brazilian citriculture. The CVC is a vascular disease with a long incubation period and symptoms similar to other disorders, and this factors difficult the CVC quantification in the field. Two methods of CVC assessment were compared in this study. The first method was based on a descriptive rating scale with four ratings, commonly used for the disease quantification. The second one was based on the incidence of symptomatic branches. The quantification of CVC through these two methods was carried out in a 10-year-old 'Natal' sweet orange orchard. The descriptive scale considered the symptoms of the entire plant. The disease incidence was evaluated in 36 branches in each plant. The assessments were conducted by three raters in 144 plants in July 2006 and July 2007 as well as in March and November 2008. The descriptive scale did not allow an accurate assessment and resulted in a moderate strength of agreement among the raters. On the other hand, the incidence quantification of CVC through the symptomatic branches showed high repeatability among the raters. We suggest the use of incidence of symptomatic branches as variable for CVC quantification.

Comparative analysis for quantification of Citrus Variegated Chlorosis in the field

Citrus Variegated Chlorosis (CVC) caused by Xylella fastidiosa is one of the most important diseases for Brazilian citriculture. The CVC is a vascular disease with a long incubation period and symptoms similar to other disorders, and this factors difficult the CVC quantification in the field. Two methods of CVC assessment were compared in this study. The first method was based on a descriptive rating scale with four ratings, commonly used for the disease quantification. The second one was based on the incidence of symptomatic branches. The quantification of CVC through these two methods was carried out in a 10-year-old 'Natal' sweet orange orchard. The descriptive scale considered the symptoms of the entire plant. The disease incidence was evaluated in 36 branches in each plant. The assessments were conducted by three raters in 144 plants in July 2006 and July 2007 as well as in March and November 2008. The descriptive scale did not allow an accurate assessment and resulted in a moderate strength of agreement among the raters. On the other hand, the incidence quantification of CVC through the symptomatic branches showed high repeatability among the raters. We suggest the use of incidence of symptomatic branches as variable for CVC quantification.