Do spatially targeted weed management strategies increase risk of herbicide resistance evolution?

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Abstract
Background: Spatially targeted spraying is an alternative to broadcast herbicide application that reduces herbicide use by restricting treatment to areas where weeds are detected. However, weed detection using remote or proximal sensing and classification algorithms is imperfect, which may allow weeds to escape treatment. This study examined the evolutionary consequences of spatially targeted spraying and evaluated whether applying herbicide to spray‐buffer zones surrounding detected weeds could compensate for reduced detection accuracy. We tested two hypotheses: first, that spray‐buffer zones can offset imperfect weed detection; and second, that lower detection accuracy and smaller spray‐buffer zones accelerate crop failure, by increasing weed survival, resistance evolution and population growth. Results: A new spatially explicit simulation model was used to represent weed populations with defined genetic architectures conferring different levels of herbicide resistance. The simulation results supported the first hypothesis, showing that spray‐buffer zones reduced the proportion of weeds escaping treatment under imperfect detection. However, the second hypothesis was not supported. More‐accurate spraying removed susceptible weeds more effectively but also imposed stronger selection for herbicide resistance. By contrast, less‐accurate detection resulted in larger weed populations, maintained a higher proportion of susceptible genotypes, and slowed the evolution of resistance. Conclusion: Spray‐buffer zones can partly compensate for imperfect weed detection in spatially targeted spraying systems. However, improving spray precision does not necessarily delay future crop failure from weed competition, because stronger short‐term control may accelerate resistance evolution. These findings highlight an important trade‐off between immediate herbicide efficacy and the long‐term durability of weed management strategies. They also underscore the importance of diversifying weed management strategies alongside the development of more‐accurate targeted herbicide application technologies. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Funding Information
  • Grains Research and Development Corporation

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