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Visual Assessment of Phony Peach Disease: Evaluating Rater Accuracy and Reliability.
Kendall A Johnson1, Phillip M Brannen1, Chunxian Chen2
1Department of Plant Pathology, University of Georgia, Athens, GA 30602.
Plant Disease
|October 12, 2023
Summary
Phony peach disease (PPD) detection using visual assessment is variable. Experienced raters showed higher accuracy and fewer false negatives than inexperienced ones, but improved detection methods are still needed.
Area of Science:
- Plant Pathology
- Agricultural Science
- Molecular Diagnostics
Background:
- Phony peach disease (PPD) is a re-emerging threat in Georgia, caused by *Xylella fastidiosa* subsp. *multiplex*.
- Current PPD management relies on visual symptom identification, which can be unreliable, especially in early stages.
Purpose of the Study:
- To compare the accuracy of visual PPD assessment with quantitative PCR (qPCR) detection.
- To evaluate the impact of rater experience on visual PPD identification accuracy.
Main Methods:
- Visual assessment of PPD symptoms by experienced and inexperienced raters on 'Julyprince' and 'Scarletprince' peach trees.
- Comparison of visual assessment results with qPCR detection of *Xylella fastidiosa* subsp. *multiplex*.
- Analysis of false positive (FP) and false negative (FN) rates associated with visual identification.
Main Results:
- Visual assessment accuracy varied, with experienced raters demonstrating higher accuracy (0.882-0.914) than inexperienced raters (0.805-0.816).
- Experienced raters had significantly lower false negative rates.
- Most raters overestimated PPD incidence, and all had both FP and FN observations.
Conclusions:
- Visual assessment of PPD provides moderate to good reliability but is prone to errors.
- Development of accurate and reliable detection methods is crucial for effective PPD management to minimize economic losses from FPs and FNs.
