Escala diagramática para avaliação da severidade da mancha foliar do eucalipto causada por Quambalaria eucalypti

Abstract

Escala diagramática para avaliação da severidade da mancha foliar do eucalipto causada por Quambalaria eucalypti. Fitopatologia Brasileira 30: 504-509. 2005. RESUMOA mancha foliar, causada por Quambalaria eucalypti, é atualmente uma das principais doenças do eucalipto (Eucalyptus spp.) na fase de viveiro. Devido à sua recente constatação no Brasil, pouco se conhece sobre a epidemiologia e o controle dessa doença. Em função da necessidade de métodos padronizados e confiáveis para sua quantificação foi elaborada uma escala diagramática contendo oito níveis (0,4; 1; 2; 4; 8; 16; 32 e 49%) de severidade. Na sua validação, quatro avaliadores inexperientes e quatro experientes avaliaram folhas com diferentes níveis de severidade, inicialmente sem o uso da escala e posteriormente com o seu uso, sendo as estimativas comparadas quanto à acurácia e precisão. Com a utilização da escala, os avaliadores apresentaram melhores níveis de precisão e acurácia. Da mesma forma, após o treinamento, os níveis também foram melhorados, principalmente para os avaliadores inexperientes. Erros na quantificação da severidade da doença ocorreram com maior freqüência entre 15 e 30% de severidade, independentemente da experiência dos avaliadores.Palavras-chave adicionais: patometria, escala diagramática, severidade, eucalipto, Quambalaria eucalypti. ABSTRACT Diagrammatic scale for assessment of eucalyptus leaf spot severity caused by Quambalaria eucalyptiThe leaf spot, caused by Quambalaria eucalypti, is presently one of the most serious diseases in eucalyptus (Eucalyptus spp.) nurseries in Brazil. Since the disease was only reported recently in Brazil, little is known about its epidemiology and control. As standardized and precise methods are needed for the disease severity evaluations, a diagrammatic scale containing eight levels (0,4; 1; 2; 4; 8; 16; 32 and 49%) of severity was developed in this study for the disease quantification. For the scale validation four inexperienced and four expert appraisers scored leaves with different levels of severity, initially without the use of the scale and later on with its use. The estimates were compared for accuracy and precision. Using of the scale the appraisers were able to get better levels of precision and accuracy. After training, the levels of precision and accuracy were also increased, mainly for the inexperienced appraisers. The greatest errors in the disease evaluations were observed between levels 15 and 30% of severity.

Diagrammatic scale for severity evaluation of the Eremanthus erythropappus–Puccinia velata pathosystem

“…The values of the linear regression coefficients indicated greater precision than accuracy in the evaluations with the scale, which was with other reports (Andrade, Alfenas, Mafia, Maffia, & Gonçalves, ; Michereff, Maffia, & Noronha, ; Nutter, ; Stonehouse, ). In the precision analysis, the coefficient of determination increased with use of the scale for all the evaluators.…”

Discovery of the eucalypt pathogenQuambalaria eucalyptiinfecting a non-Eucalyptushost in Uruguay

“…The discovery of Q. eucalypti on a native Uruguayan tree is disturbing, since the fungus is a virulent primary pathogen that has the capacity to cause severe disease (Wingfield et al 1993;Alfenas et al 2004;Andrade et al 2005;Roux et al 2006). Host shifts, such as the one that appears to have occurred with Q. eucalypti, are relatively well known amongst tree pathogens (Slippers et al 2005;Woolhouse et al 2005) and many have lead to serious disease epidemics.…”

“…(Alfenas et al 2001). It is currently responsible for significant disease problems during clonal propagation of Eucalyptus (Alfenas et al 2004;Andrade et al 2005).…”

Quambalaria eucalypti a pathogen of Eucalyptus globulus newly reported in Portugal and in Europe

“…Disease severity was evaluated 12 days after inoculation on two median leaves of each plant using a diagrammatic scale comprising eight levels of severity (0.4; 1; 2; 4; 8; 16; 32; and 49% of leaf area affected) as developed by Andrade et al (2005) for the determination of Q. eucalypti severity. As the disease severity data were ordinal, the nonparametric Kruskal-Wallis and post hoc multiple comparisons tests were used to determine the significance of differences between treatment means.…”