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

Abstract

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.