Elaboração e validação de escala diagramática para avaliação da severidade de oídio em folhas de mamoeiro

Abstract

RESUMOCom o objetivo de facilitar e padronizar as avaliações da severidade de oídio (Streptopodium caricae) em folhas de mamoeiro elaborou-se e va lidou -se uma esca la diagramá tica com os segu intes níveis de severidade: 0,6; 1,2; 2,5; 5,0; 10,0 e 20,0%. Sem a escala, todos os avaliadores superestimaram a severidade da doença. Com a escala, os avaliadores obtiveram melhores níveis de acurácia, com erros absolutos Santos, P.H.D.; Vivas, M.; Silveira, S.F.; Silva, J.M.; Terra, C.E.P.S. Elaboração e validação de escala diagramática para avaliação da severidade de oídio em folhas de mamoeiro. Summa Phytopathologica, v.37, n.4, p.215-217, 2011. Palavras-chave adicionais:Carica papaya, Streptopodium caricae, quantificação, severidade.concentrando-se na faixa de 5%, sendo muitas vezes inferiores a esse valor e pou ca s vezes ultrapassa ndo os 1 0%. Todos os a va lia dores a presenta ra m boa repetibilida de e eleva da reprodu tibilida de da s estimativas com a utilização da escala. A escala diagramática proposta mostrou-se adequada para avaliação da severidade de oídio em folhas de ma moeiro.Keywords: Carica papaya, Streptopodium caricae, assessment, severity. ABSTRACTA diagrammatic scale for powdery mildew (Streptopodium caricae) in papaya leaves was elaborated and validated in order to standardize the disease severity assessments. The proposed scale presented severity levels of 0.6, 1.2, 2.5, 5.0 , 10.0 and 2 0.0%. Without the scale, all evalua tors overestima ted the disea se severity. When the sca le was u sed by the eva lu a tors, better a ccu ra cy and precision levels were Santos, P.H.D.; Vivas, M.; Silveira, S.F.; Silva, J.M.; Terra, C.E.P.S. Elaboration and validation of a diagrammatic scale to assess powdery mildew severity in papaya leaves. Summa Phytopathologica, v.37, n.4, p.215-217, 2011. obta ined, althou gh there was a severity u nderestima tion tendency, with absolute errors around 5% and many times inferior to this value a nd a few times a bove 1 0 %. The eva lu a tors presented good repeatability and high reproducibility of estimates when the scale was used. The diagrammatic scale was suitable for powdery mildew severity evaluation in papaya leaves.

Diagrammatic scale of severity for postharvest black rot (Ceratocystis paradoxa) in coconut palm fruits

“…Most deviations were negative, indicating a tendency towards severity underestimation. These results are similar to those found in diagrammatic scale validation studies involving other pathosystems, such as fruit and leaf diseases of papaya (18,24) and brown eye spot in red and yellow coffee cherries (13). Accuracy of visual severity estimates without the diagrammatic scale indicated average R 2 values of 0.59, within the range from 0.20 to 0.79, and amplitude around 0.59.…”

Elaboration and validation of a diagrammatic scale to assess downy mildew severity in grapevine

“…These scales can be used to standardize the severity estimation and reduce the subjective of disease severity visual estimates. The diagrammatic scales is expected to be easy and quick for a wide range of conditions with reproducible, accurate, and precise results (MALAGI et al, 2011;SACHS et al, 2011;SANTOS et al, 2011;YADAV et al, 2012). Accuracy refers to how faithful an estimate is from the actual amount of the evaluated disease, while precision corresponds to the confi dence and/or repeatability associated to such estimate (NUTTER JR. & SCHULTZ, 1995, ANGELOTTI et al, 2008MICHEREFF et al, 2009).…”

Phenotypic characterization of papaya genotypes to determine powdery mildew resistance

“…Disease severity was assessed on leaves with petiole attachment in the axil of newly opened flowers, on a diagrammatic scale for powdery mildew proposed by Santos et al (2011), in December 2011and February 2012. The experiment was arranged in a randomized complete block design with two replications, evaluting 59 genotypes.…”