Development and validation of a standard area diagram (SAD) set for assessing Alternaria black spot severity in pecan leaves

Abstract

Abstract Pecan ( Carya illinoinensis ) cultivation is expanding in Argentina, with Catamarca Province emerging as a significant production region. However, fungal diseases such as Alternaria black spot (ABS), caused by Alternaria spp., pose an increasing threat to crop yield and health. Considering that disease quantification is crucial for epidemiological studies and management, this study aimed to design and validate a standard area diagram (SAD) set to improve the visual estimation of ABS severity on pecan leaves. Using 255 diseased leaves, an eight-image SAD set with severity levels that linearly ranged from 2.2–88.9% was designed. Thirty-four raters participated in the validation process using the online platform TraineR2 in two phases: unaided and aided assessments. The use of the SAD set significantly improved accuracy metrics. Lin’s concordance correlation coefficient (CCC) increased from 0.93 to 0.97, while precision (r) rose from 0.92 to 0.97. Additionally, inter-rater reliability, measured using the intraclass correlation coefficient (ICC), improved from 0.86 to 0.93. This study demonstrates the effectiveness of the SAD set tool in enhancing the accuracy and consistency of ABS severity estimations, highlighting its potential as a practical resource for pecan producers and researchers.

Plant phenotyping relevance

ペカン葉の病斑重症度という植物状態を視覚推定する標準面積図（SAD）を開発・検証しており、表現型取得・評価手法が研究の中心です。

Code and data availability

The preprint explicitly states that the datasets generated and analyzed (the ABS severity leaf-image data and validation data) are publicly available in an INTA institutional repository. The TraineR2 and SADBank platforms are third-party tools, not paper-specific assets.