Site-Specific Risk Factors for Ray Blight in Tasmanian Pyrethrum Fields

Area of Science:

• Plant Pathology
• Agricultural Meteorology
• Crop Science

Background:

• Ray blight, caused by Phoma ligulicola var. inoxydablis, significantly reduces pyrethrum yield and growth.
• Accurate forecasting of disease outbreaks is crucial for effective crop management.

Purpose of the Study:

• To develop predictive models for pyrethrum ray blight severity using edaphic and weather variables.
• To establish decision-support tools for optimizing disease management strategies.

Main Methods:

• Logistic regression was employed to model disease severity based on environmental factors.
• Receiver operating characteristic (ROC) curve analysis was used to evaluate model performance and economic thresholds.

Main Results:

• September and October ray blight models achieved classification accuracies of 64.8% and 72.6%, respectively.
• Predictive thresholds were identified, and ROC analysis suggested routine disease management when prevalence exceeds 0.2.

Conclusions:

• Developed models provide a foundation for a decision-support system for pyrethrum ray blight.
• Integrating economic factors into predictive models optimizes management decisions and minimizes costs.