Top-cutting reduces seed return and seedbank replenishment in important grass weed species, supporting regenerative agriculture

Top-cutting (‘weed-surfing’) is a pre-harvest strategy that reduces weed seedbank inputs by mechanically removing weed seed heads before seed shedding. To be effective, it requires weeds to set their inflorescences above the crop canopy. Here, a multi-factor two-year field study was conducted to evaluate the efficacy of this approach for four economically important grass species using two winter wheat varieties. The results demonstrate that efficacy is highly species-specific and dependent on cutting frequency and climatic conditions. While three repeated cutting treatments provided the highest level of control, a single cut, particularly applied at an early reproductive phase, was largely ineffective, removing less than 39 % of heads in the best case. The ‘mid-single cutting’ and ‘two-cutting’ treatments demonstrated intermediate and similar efficacy, reaching up to 81.9 %. Avena fatua was the most susceptible, with three cuts removing 92–96 % of seed heads. Lolium multiflorum was also well-controlled (69–80 % removal). The technique offered moderate, yearly variable efficacy against Alopecurus myosuroides (37–75 % removal) and was largely ineffective against Bromus secalinus (4–73 % removal), particularly in a drier year. A shorter-strawed wheat variety consistently improved removal efficacy by 14–35 % for A. myosuroides and B. secalinus . Furthermore, compensatory head production was limited and context-dependent, observed mainly in A. myosuroides and L. multiflorum in the wetter year. While early cutting removed fewer seed heads, it resulted in low seed viability (