Economic Costs of Sharing the Harvester in the Control of an Invasive Weed

Gabriel Pardo,Yolanda Martínez,Miguel I Gómez,Alicia Cirujeda

doi:10.3390/su12219046

Abstract

Spatial externalities, such as the sharing of harvesting equipment by many farmers, have an impact on the control of invasive species in the agricultural environment. In these cases, the regulator must design a set of measures to promote coordinated control by affected parties. We aim to analyze the determinants of private versus collective control efforts in the case of a particular invasive species (teosinte) occurring as a weed in corn fields throughout North-Eastern Spain. Using a simple discrete space-dynamic framework, we model the effect of the decisions made by the farmer of an infested plot on a noninfested plot, with the harvester being the only potential pathway for the invader to spread and assuming a one-way invasion. The results reveal that failure to adopt optimal cooperative strategies causes losses to other plots if they become infested amounting to an annual average of EUR 322/ha, when the infestation is low, and EUR 364/ha, when it is high. Results suggest that cleaning the harvester, a measure currently recommended by the regulatory agency in low-infestation cases but that does not guarantee that the machine is completely clean, is not socially optimal if monocropping practices are permitted in the region.

Highlights

The emergence of a new invasive species that behaves as a weed in crop fields is a major challenge for the agents involved in controlling it
The results reveal that failure to adopt optimal cooperative strategies causes losses to other plots if they become infested amounting to an annual average of Expected Discounted Average Benefits (EUR) 322/ha, when the infestation is low, and EUR 364/ha, when it is high
The primary reason why these externalities exist in the case of agricultural fields is that the individuals involved in control base their decisions on their own farms [1], in other words, on a subset of the total area at risk of invasion. This private perspective ignores the link between the control efforts made by neighboring fields, while spatial externalities are likely when control efforts affect the spread of an invasive species across the landscape [2,3]

Summary

Introduction

The emergence of a new invasive species that behaves as a weed in crop fields is a major challenge for the agents involved in controlling it (farmers and regulators). Identifying possible dispersal pathways—which are normally affected by control externalities—among neighboring plots is of great importance Evaluating these externalities is crucial in the practical framework so that regulators can adequately guide farmers in their control decisions. The primary reason why these externalities exist in the case of agricultural fields is that the individuals (or stakeholders) involved in control base their decisions on their own farms [1], in other words, on a subset of the total area at risk of invasion. This private perspective ignores the link between the control efforts made by neighboring fields, while spatial externalities are likely when control efforts affect the spread of an invasive species across the landscape [2,3]

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Results

Conclusion