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

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.

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.

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.