Chloe McCallum

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McCallum

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Chloe

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0000-0002-7947-0261

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Publications 1 - 10 of 16

Barriers to evidence use for sustainability: Insights from pesticide policy and practice
Hofmann, Benjamin; Ingold, Karin; Stamm, Christian; et al. (2023)
Ambio
Calls for supporting sustainability through more and better research rest on an incomplete understanding of scientific evidence use. We argue that a variety of barriers to a transformative impact of evidence arises from diverse actor motivations within different stages of evidence use. We abductively specify this variety in policy and practice arenas for three actor motivations (truth-seeking, sense-making, and utility-maximizing) and five stages (evidence production, uptake, influence on decisions, effects on sustainability outcomes, and feedback from outcome evaluations). Our interdisciplinary synthesis focuses on the sustainability challenge of reducing environmental and human health risks of agricultural pesticides. It identifies barriers resulting from (1) truth-seekers’ desire to reduce uncertainty that is complicated by evidence gaps, (2) sense-makers’ evidence needs that differ from the type of evidence available, and (3) utility-maximizers’ interests that guide strategic evidence use. We outline context-specific research–policy–practice measures to increase evidence use for sustainable transformation in pesticides and beyond.
Data on Swiss grapevine growers’ production, pest management and risk management decisions
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2023)
Data in Brief
We present survey data from 436 grapevine growers across Switzerland and their production, pest, and risk management decisions. The online survey was conducted in spring 2022 in the three main official languages in Switzerland (German, French, Italian). The survey was used to obtain information on variety choice and farm management strategies, as well as farmer, farm, and spatial environmental characteristics. Moreover, we collected information around fungus-resistant grapevine varieties such as knowledge, attitudes, and perceptions of these varieties. We also elicited the current cultivation and growers’ intentions on future acreage under these varieties. In addition, data were collected on growers’ pest management strategies against weeds, insects, and fungi. Characteristics of the farm manager collected include education, farming goals, wine-related expertise, and information sources used. Information about the farm consist of marketing channels, labels, direct payment schemes, production systems and pesticide application machinery, among other details. Moreover, risk and time preferences, self-efficacy and locus of control were collected via self-assessed scales. The survey data were matched with spatial climatic data on municipality level (e.g. on temperature, precipitation, the number of yearly hail days, average sunshine duration and relative humidity) as well as pest pressure (e.g. infection risk by Oidium and Peronospora viticola) at weather station level.
Nudging farmers towards low-pesticide practices: Evidence from a randomized experiment in viticulture
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2023)
Journal of the Agricultural and Applied Economics Association
Planting fungus-resistant grapevines is an effective way to reduce pesticide use in grapevine production, but their uptake remains low. We explore whether providing personalized or general information on growers’ use of environmentally toxic fungicides changes their planting intentions of fungus-resistant varieties (i.e. salience nudging), conducting a randomized experiment with 436 grapevine growers in Switzerland. We find no effect of providing personalized or general information on the intended plantation share of fungus-resistant varieties. However, exploratory analyses suggest that growers' perceptions about fungus-resistant varieties may cause the null result, with growers having non-compliant environmental perceptions being particularly prone to boomerang effects.
Farm characteristics determine why a large share of organically produced wine is not labelled as organic
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2024)
Environmental Research Communications
Organic agricultural production is increasing globally and is of high policy relevance, particularly in Europe. Various measures incentivize farmers to adopt organic practices, such as direct payments and labelling. We here address a rarely considered aspect of organic production, that not all organic producers in Europe opt for organic labelling for their products at the point of sale. We investigate the discrepancy between organic production and labelling in Swiss viticulture. Out of 115 grapevine growers who adhere to organic principles in production, 43.5% do not use organic labelling when marketing their wines. We find that especially farms using alternative labelling strategies (e.g. for fungus-resistant varieties), smaller farms and farms less specialized in viticulture to be more likely to forgo organic labelling. We draw conclusions for policy and science. For example, our findings show that there may be, for some crops, more organic products on shelves than indicated from sales statistics of organically labelled products. The use of statistics that indicate the share of sales of organic products for specific products and food sales at large may thus be misleading.
The effect of geographical denomination on the uptake of fungus-resistant grapes
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2025)
Applied Economic Perspectives and Policy
Grape production for wine making is of great economic and cultural importance in Europe, but is heavily dependent on pesticides. Reducing pesticide use and associated risks is a policy goal in several countries, particularly in Europe. The most effective strategy to substantially reduce pesticide use in grape production is the planting of fungus-resistant varieties, which are less susceptible to common fungal infections and thus allow a massive reduction in pesticide treatments. However, their use remains low. One possible reason may be that planting new varieties may conflict with policies supporting geographical denomination systems, which tend to focus on traditional varieties. We provide the first study of how geographical denomination systems directly affect the adoption of fungus-resistant varieties. Using a novel and uniquely detailed dataset of 54,483 variety-level observations from 381 vineyards in Switzerland, we find that fungus-resistant grape varieties are 2% more likely to be adopted by growers if they can be sold under geographical denominations. Thus, expanding the eligibility of fungus-resistant varieties in geographical denomination lists could be a straightforward policy measure to stimulate their adoption. However, the effects are small, so complementary policies are needed.
Towards sustainable crop protection in agriculture: A framework for research and policy
Finger, Robert; Sok, Jaap; Ahovi, Emmanuel; et al. (2024)
Agricultural Systems
CONTEXT European countries have set ambitious targets to reduce the risks of pesticide use. Achieving these targets will require a large proportion of farmers to adopt sustainable crop protection practices. However, how to enable this transition and what are the best policies to support farmers remain open questions. OBJECTIVE Here, we provide a coherent review of existing evidence and new insights into farmer decision-making and policy analysis in the context of the transition to more sustainable crop protection. We synthesise and extend the empirical evidence and the conceptual and methodological foundations to examine farmers' decisions to adopt sustainable crop protection and to assess the potential of different policy measures to support this transition. Our analysis focuses on European agriculture. METHODS We provide a framework and synthesise evidence by reviewing the literature and combining agronomic and economic perspectives. We focus on three issues: i) indicators for empirical analyses of adoption of sustainable crop protection practices; ii) behavioural perspectives on farmer adoption; iii) insights into methodological approaches for assessing adoption of sustainable crop protection practices and related policies. RESULTS AND CONCLUSION We have identified four main findings and implications. First, sustainable crop protection practices consist of combinations and bundles of individual measures that are not currently regularly considered in policy instruments and policy analysis. Second, definitions of adoption should move from simple adoption metrics to impacts, for example on pesticide risk reduction. Third, behavioural factors are highly relevant to farmers' adoption decisions, but are currently under-researched and under-represented in the field of sustainable crop protection practices. Fourth, the tools currently used for policy analysis do not allow these key aspects to be represented. We draw policy conclusions. SIGNIFICANCE Our analyses help guide policy decisions to achieve pesticide use and risk reduction objectives, and have implications for pesticide policy in Europe and beyond. We identify gaps in current conceptual and methodological approaches, promising avenues for future research, and ways to make results more coherent and comparable. Our analysis thus provides new insights and templates to guide future research and policy analysis on the adoption of sustainable crop protection approaches.
Consumers' responses to food fraud risks: An economic experiment
McCallum, Chloe; Cerroni, Simone; Derbyshire, Daniel; et al. (2022)
European Review of Agricultural Economics
This artefactual field experiment explores consumers' willingness-to-pay (WTP) price premiums for fish products to avoid the risk and uncertainty of purchasing inauthentic produce. The influence of subjective probabilistic beliefs, risk and ambiguity preferences is investigated. Participants' WTP is elicited using experimental auctions, while behavioural factors are elicited using incentivised and incentive-compatible methods: the quadratic scoring rule and multiple price lists. Results show that consumers are willing to pay a premium to avoid food fraud and purchase an authentic fish product. This premium is higher under uncertainty than risk, likely driven by ambiguity preferences which affect consumers' purchasing under uncertainty.
Determinants of the adoption of fungus-resistant grapevines: Evidence from Switzerland
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2024)
Journal of Wine Economics
The adoption of fungus-resistant grapevines may be a key strategy for substantially reducing fungicide use in pesticide-intensive viticulture. In a representative survey conducted among 436 grapevine growers in Switzerland, we elicited growers' expected share of land devoted to fungus-resistant varieties in ten years. More specifically, using regression analyses, we explore the main predictors behind the stated adoption intentions. We find that one-third of new plantings in the next decade will be fungus-resistant varieties. As a result, the expected share of land devoted to fungus-resistant varieties in ten years is 27.4% (compared to 10.2% in 2022), thus increasing by 169%. Farmer- and farm characteristics explain most of the adoption dynamics, especially growers' beneficial health perceptions about fungus-resistant varieties, which correlate positively with their expected land share devoted to these varieties. Moreover, non-organic grapevine growers are particularly likely to increase their land devoted to these varieties. These findings have important implications for agricultural policy and industry in Europe and elsewhere, facilitating the expected plantation increase using a policy mix tailored to farmer- and farm-level characteristics.
Bidding behaviour in experimental auctions under risk and uncertainty
McCallum, Chloe; Cerroni, Simone; Derbyshire, Daniel; et al. (2025)
Theory and Decision
This paper explores bidding behaviour under risk and uncertainty using the Becker-DeGroot-Marschak mechanism (BDM) and second price auction (SPA). It investigates whether values elicited via the two mechanisms are consistent and whether bidding behaviour can be influenced by differences in the number and type of sources of risk and uncertainty that people face when exposed to the two mechanisms. In our experiment, subjects are exposed to non-monetary lotteries where they bid for a high-quality seafood product, but there is a chance (known or unknown) that they receive a lower quality seafood product instead. Results indicate that bidding behaviour can be influenced by the number and type of sources of risk and uncertainty that subjects face and subjects' bidding behaviour is only consistent with standard theories of decision making under risk and uncertainty when they bid on a risky product in the SPA. Despite this, BDM and SPA elicit equal values under risk and uncertainty in this study.
Spraying for the beauty: Pesticide use for visual appearance in apple production
Zachmann, Lucca; McCallum, Chloe; Finger, Robert (2024)
Agricultural Economics
Pesticides are used to reduce yield losses and to enhance the visual quality of products. However, pesticide use raises concerns due to negative health and environmental effects, hence ambitious policy goals for their reduction have been established. Reducing pesticides which mainly focus on visual quality of products could be an efficient strategy to contribute to these goals, without reducing food production. However, the role of “cosmetic” pesticide use is so far not well documented and understood. Here, we quantify cosmetic pesticide use and the influence of supply chain characteristics on their use. We focus on table apple production, where the visual quality of products is a key aspect. Using a sample of 196 apple growers in Switzerland, we find that 23.5%–59.2% of growers use cosmetic pesticides for the apples’ visual appearance. Farms mainly marketing via intermediaries are 23.9-29.6% more likely to spray cosmetic pesticides for visual purposes compared to farms mainly direct marketing. Our findings highlight the role of supply chains in farmer decision-making, recommending a decrease in the focus on visual product quality, especially in retail environments, thus minimizing unnecessary and irreversible risks of pesticide exposure by farmers without compromising food security.

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Chloe McCallum

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