Field margin plantings do not increase weed pressure within crops relative to other margin management strategies

Abstract Biodiversity plantings are effective methods of enhancing on-farm biodiversity. However, farmers are often hesitant to place them adjacent to crop fields due to concerns that they may harbor problematic weeds and pest arthropods, or that the intentionally planted species may escape into the crop and act as weeds. The objective of this research was to compare weed and arthropod communities in planted versus conventionally managed field margins at two sites in New York State. Planted treatments were seeded with either native wildflowers or grasses and then either mowed infrequently or unmanaged after planting. Conventional field margin management treatments included infrequent and frequent mowing, glyphosate application, and an unmanaged control. Measurements included both seedbank and aboveground plant density and diversity, plant biomass, and the abundance of both beneficial and pest arthropods. Pest arthropod abundance both in the margin and in the crop was not affected by the field margin management strategy. Arthropod abundance and plant richness and diversity, both within fields and field margins, were not strongly affected by the field margin management method. Once the plantings were established, weed density was lower within planted margins than conventionally managed margins (P = 0.0002), with a difference of 92.8% per 0.5 m 2 in 2025. Treatment affected weed biomass (P = 0.002), but treatment means differed significantly at only one site in 2024 according to Tukey’s HSD. Overall, our results indicate that the establishment of field margin plantings is unlikely to exacerbate weed pressure from field margins.