<p>Pesticides support crop production, enhancing global food security, but are associated with serious environmental and health risks. Factors that promote overuse of pesticides are therefore of great concern. Pest control advisors (PCAs) are agricultural professionals who scout fields for pests and may recommend pesticide applications. We test two hypotheses regarding the influence of PCAs on pesticide use by California farmers, contrasting four groups: independent PCAs, sales PCAs, farm-staff PCAs, and farmer PCAs. The long-discussed conflict of interest hypothesis posits that sales commissions earned by PCAs who work for agricultural chemical retailers (“sales PCAs”) incentivize pesticide use; it predicts elevated use of all pesticides by farmers advised by sales PCAs. The risk aversion hypothesis posits that the risk of damaging pest outbreaks incentivizes pesticide use; it predicts elevated pesticide use when targeting pests that can exhibit outbreaks (arthropods and plant pathogens) but not when targeting non-outbreak pests (weeds). We assembled a dataset of pesticide use on nearly 600,000 crop-years grown in California from 2012 to 2021 by farmers advised by different types of PCAs. Our analysis provides little to no support for the conflict of interest hypothesis; farmers advised by sales PCAs used slightly less pesticides than farmers advised by independent PCAs (who receive no sales commission). Instead, our analysis reveals pesticide use consistent with the risk aversion hypothesis, with elevated use of pesticides by one group of PCAs (farm-staff) when managing arthropods and pathogens, but not when managing weeds. Risk aversion, rather than sales commissions, may be shaping pesticide use in California.</p>