Leaf Doctor: A New Portable Application for Quantifying Plant Disease Severity

Area of Science:

• Plant pathology
• Digital image analysis
• Mobile technology in agriculture

Background:

• Accurate plant disease severity assessment is crucial for effective crop management.
• Traditional methods can be time-consuming, subjective, and require specialized expertise.
• There is a need for accessible and objective tools for disease diagnosis in the field.

Purpose of the Study:

• To evaluate the accuracy, precision, and robustness of the Leaf Doctor smartphone application for quantifying plant disease severity.
• To compare the performance of Leaf Doctor against a discipline-standard assessment tool.
• To highlight the practical advantages of using Leaf Doctor in plant disease management.

Main Methods:

• Development of an interactive smartphone application (Leaf Doctor) for image analysis.
• User interaction involves selecting healthy tissue colors and adjusting a threshold slider to isolate diseased areas.
• Calculation of disease severity percentage based on pixel analysis of the selected symptomatic tissues.

Main Results:

• Leaf Doctor demonstrated high accuracy in disease severity estimation (R² ≥ 0.79) compared to the Assess software.
• Precision was generally good, with low coefficients of variation (0.51% to 14.1%) across various diseases.
• A negative relationship was observed between coefficient of variation and mean disease severity, indicating better precision with higher severity.

Conclusions:

• Leaf Doctor provides accurate and precise estimates of plant disease severity.
• The application offers advantages such as speed, low cost, and ease of use for plant disease diagnosis.
• Leaf Doctor is a promising tool for researchers, extension agents, and growers to monitor plant health.