Projects Funded for Ryan Olver


Methyl Bromide: still around after all these years - A Case Study of Structural Changes in Agriculture

David Zilberman and Ryan Olver


Specific Objectives:

  1. To understand why the use of an expensive and environmentally problematic chemical has persisted for decades - and how its use patterns have adapted to regulations and have affected production patterns and land use. This will be done through:
    (a) A review of the history of methyl bromide through literature in agricultural and environmental sciences and economics. This review will allow for the development of a timeline of the technology and its patterns of use over time. This review will emphasize the dominance of methyl bromide in soil fumigation, its interaction with other practices, and how its introduction led to structural changes of California strawberry production. An important part of the analysis is the discovery of new data sources.
    • Initial analysis suggests that the introduction of methyl bromide, together with other fumigants, led to major increases in yield and major changes in crop rotation. We will continue to refine our analysis, obtain new data sources, and thus lay the foundation for our econometric analysis and simulations.
    (b) Econometric analysis of the impact of the introduction of methyl bromide and other fumigants on yield of strawberries (with possible expansion to other crops). This will use data on yield per acre, acreage, prices, fumigant use, and other variables at the county level over time, beginning in the 1950s.
    (c) Econometric analysis of the impact of fumigant changes on land use patterns using county level crop report data. We will also use data on prices and other economic variables to assess changes in land use patterns over time.
  2. To develop an economic modeling framework that will enable simulation of the economic impact of changes caused by the introduction and use of methyl bromide fumigation over time.
    • Impacts on land use and crop rotation
    • Gains in terms of output and economic surplus due to reduced incidence of disease (root rot, Verticillium wilt)
    • Post-fumigation land value
    • Cultivar selection criteria
  3. The analysis will assess how these impacts change in response to environmental regulations and technology modification.

Proposal Narrative:

Methyl bromide has been one of the most prominent agricultural chemicals in California since UC scientists discovered fumigation strategies using methyl bromide, in combination with other chemicals, in the 1950s. This discovery provided broad spectrum pest control and led to changes in land use and profitability increases in multiple crops. Strawberry growers in particular were able to avoid costly crop rotations, grow strawberries on the most suitable land, and increase both yield and quality.

Methyl bromide was scheduled to be completely phased out of soil fumigation in the US by 2005 because of its contribution to ozone depletion. Scientists have searched for pesticide substitutes for several decades, due to its (1) high cost and (2) environmental impact. In the absence of an effective substitute, California strawberries were provided critical use exemptions, which were renewed until 2016. Even after these ceased, substantial amounts of methyl bromide are still used to prepare plants, which are then transplanted to the field.

The economics of eliminating methyl bromide and the status of available alternatives have been discussed extensively. In contrast to the analysis of the impacts of phaseout, economists have paid scant attention to the introduction of methyl bromide and its history. Much of the research on the economics of pest control emphasized the cost of replacement of one technology with another. However, it has often neglected the environmental side effects of these potential alternatives.[9] We aim to show in this study that understanding the evolution of a pest control strategy and its impacts, via a multidisciplinary approach, is essential in assessing the impact of regulation in the present and design of future policies.

Our study will build on earlier investigations we conducted showing that the introduction of methyl bromide resulted in fundamental changes to the strawberry industry, and secondary effects in California agriculture as a whole. The replacement of earlier practices with fumigation allowed growers to (1) shift from multi-year planting schedules to annual ones, (2) improve fruit yield and quality, (3) reduce rotation among crops, and (4) generate positive externalities where lands, previously used to grow strawberries, remained relatively disease-free and would improve subsequent production. Furthermore, disease control reduced selection pressure for resistance traits in new strawberry cultivars, simplifying the breeding process.

Our project consists of several parts. We will expand our literature review of methyl bromide fumigation, which we have constructed over the past two years. The literature review provides us with familiarity with multiple data sources and will guide us in pursuing objective 1A. We aim to adapt models from pesticide economics (Waterfield and Zilberman, 2012; Samtani et al, 2012)[8][11] to incorporate some of the major features of this narrative. These models will provide the foundation of our econometric analysis and simulation. One of our challenges will be to use our model and data for the development of a counterfactual model to estimate acreage savings from cultural changes, including the shift away from migratory planting and the introduction of monocropping, as well as the impact of cultivar selection criteria emphasizing yield and quality over disease resistance.

Project Relevance:
This project will demonstrate the importance of incorporating historical analysis with standard econometric analysis, and will additionally demonstrate that understanding the importance of path dependency in assessing impacts of policies. It will also help to understand some of the challenges that are associated with replacing “undesirable” pest control strategies in agriculture, and the resulting direct and indirect implications. It will allow us to better assess the value of methyl bromide and why it continues to persist despite significant efforts to replace it. It may also provide better justification for more novel strategies, including more precise fumigation, use of biotechnology, and improved cultural practices.