A diagramatic scale was developed and validated to assess dendrophoma severity in strawberry, caused by Dendrophoma obscurans (Ell &Ev.)H.W. Anderson. The scale was developed considering the maximum and minimum severity limits of disease observed in the field and the intermediate levels followed logarithmic increments according to the "Stimulus Law by Weber-Fechner". Initially the estimate of severity was performed without the use of the scale in 25 leaves with different levels of severity, validation was carried out by eight appraisers, without previous practice in assessing dendrophoma blight in strawberry. Then, the appraisers estimated the severity of the same leaves previously assessed using the proposed diagrammatic scale, with six levels of disease severity: 0.9; 2.9; 9.1; 25.2; 53.3 and 79.5%. Assessments with the diagrammatic scale were of great precision and higher accuracy for all appraisers. The proposed diagrammatic scale was considered adequate to estimate dendrophoma blight severity in strawberry and will be used in epidemiological studies and in the evaluation of control strategies for this disease.
Dendrophoma obscurans; Fragaria x ananassa Duch; pathometry
