Economic Benefit Analysis of the Late Blight Forecasting Systems

Yangxuan Liu, Purdue University

Abstract

This dissertation focuses on risk management strategies that employ precision agriculture technology. Of interest in this study are the new potential applications of precision agriculture in the area of potato and tomato plant-disease control for late blight. The precision agriculture technology understudy in this dissertation, named BlightPro decision support system (DSS), links weather information with crop protection strategies for fungicide application. Essay one and essay two identify the financial value of adopting precision agriculture technology by considering growers’ risk perceptions. Essay one (chapter three) and essay two (chapter four) develop analysis for potato and tomato production, respectively. Three fungicide scheduling strategies were evaluated: calendar-based strategy, BlightPro decision support system based strategy (DSS-based strategy), and no fungicide application (unsprayed control). Distributions of net returns to all costs excluding fungicide cost and application cost per acre (net return per acre) for the calendar-based and the DSS-based strategies at each location for each crop are constructed using results from 14 years of computer simulation experiments in the United States. These distributions are then compared using three risk analysis methods: stochastic dominance, stochastic dominance with respect to a function, and stochastic efficiency with respect to a function. Fifty-nine locations in the United States were used to conduct the analysis for potato production, and 25 locations in the United States were used to conduct the analysis for tomato production. For potato production, the DSS-based strategy was identified as the most effective approach to manage late blight in terms of disease suppression, net return per acre, and risk-adjusted net return. Results indicate that the DSS-based strategy is the preferred method to schedule fungicide applications. Under high disease pressure circumstances, the economic benefits to potato growers of adopting the precision agriculture technology ranged from $30 to $573 per acre. Except for growers raising the moderately resistant potato cultivars, more risk averse individuals tended to benefit more from adopting the precision agriculture technology. For tomato production, the analysis was conducted for four levels of tomato yield for the DSS-based strategy, including 0%, 5%, 10%, and 15% of tomato yield improvement when using the DSS-based strategy. Results showed that the DSS-based strategy was more effective to manage late blight in terms of disease suppression. The preferred fungicide application strategy varied with different levels of tomato yield improvement for the DSS-based strategy. With 0% yield improvement for the DSS-based strategy, the economic benefits to tomato growers of adopting the precision agriculture technology ranged from -$28 to $48 per acre for the DSS-based strategy. With 5%, 10%, or 15% tomato yield improvement for the DSS-based strategy, the economic benefits to tomato growers ranged from $496 to $603 per acre with 5% yield improvement, $1,020 to $1,158 per acre with 10% yield improvement, and $1,543 to $1,714 per acre with 15% yield improvement. Essay three evaluates the thresholds combination of blight unit and fungicide unit in the BlightPro DSS to obtain the economic threshold. This essay introduced economic factors to evaluate the thresholds in the BlightPro DSS for the highest average net return thresholds while maintaining or reducing the average AUDPC and maintaining or improving the average fungicide use efficiency from the previous thresholds. Using 10 years of computer-simulated experiments from 152 locations in the United States, we compared different combinations of blight unit and fungicide unit thresholds in terms of disease severity (AUDPC), fungicide use efficiency, and net return per acre to manage potato late blight disease. The results showed that the economic thresholds could improve disease suppression and farming profit relative to the previous critical thresholds while maintaining fungicide use efficiency and improve late blight disease management.

Degree

Ph.D.

Advisors

Langemeier, Purdue University.

Subject Area

Agricultural economics

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