Flexible canopy opening improves spray coverage in dense crop canopies: modelling and field evaluation.

BACKGROUND: Uniform spray delivery within dense crop canopies is limited by upper-canopy interception, which restricts droplet transport to inner, middle and lower layers. This study evaluated a flexible canopy-opening strategy designed to form a temporary transport pathway. Soybean (Glycine max (L.) Merr.) was used as the test crop, and explicit finite element modelling, high-speed imaging and field water-sensitive paper (WSP) trials were combined to assess canopy-opening response, stem loading and WSP-measured coverage. RESULTS: Model-predicted maximum opening distance had a mean absolute percentage error of 7.37%. Within the tested range, opening depth was the factor most strongly related to maximum opening distance, which was used as a proxy for canopy opening. Increasing opening depth from 10% to 30% increased maximum opening distance from 187.15 to 385.91 mm. At 30% opening depth and 0.75 m s-1, middle- and lower-adaxial WSP-measured coverage reached 52.25% and 20.77%, compared with 18.56% and 5.23% without opening. Adaxial and abaxial interlayer coefficients of variation decreased by 62.37% and 40.15%, respectively. The simulated stem loading remained below the measured bioyield threshold. CONCLUSION: Flexible canopy opening improved spray access to poorly covered inner canopy layers by temporarily increasing canopy openness. Under the tested soybean conditions, 30% opening depth at 0.75 m s-1 produced the highest mean middle- and lower-canopy WSP-measured coverage and the greatest interlayer coverage uniformity within the tested range. These findings support flexible canopy opening as a practical approach for improving WSP-measured coverage and spray delivery potential at difficult-to-reach canopy positions. © 2026 Society of Chemical Industry.