Camera-guided inter-row hoeing in winter oilseed rape with different inter-inter-row spacing

New cropping practices such as single-grain seeding, lower seed densities with stronger cultivars, wide inter-row spacings and camera-guided side-shift control for weed hoeing facilitate mechanical weed control in oilseed rape. In a two-year field study in Southwestern Germany, camera-guided inter-row hoeing was compared to standard herbicide treatments and untreated control. Seeding with 12.5, 25 and 50 cm inter-row spacing was included as a second factor in the experiment. Weed and crop density were measured directly after treatment. Weed and crop biomass, oilseed rape root diameter and nitrogen uptake were assessed before winter. Seed yield was measured at harvest with a plot combine harvester. In 2021, hoeing in 50 cm inter-row spacing achieved equal weed control efficacy as the herbicide treatment (65-75%). In 2022, hoeing did not reduce weed density, probably due to heavy rainfalls during the first and second pass of hoeing. However, herbicide treatments controlled 92% of the weeds. In 2021, hoeing significantly increased oilseed rape shoot biomass and root diameter compared to the herbicide treatment and the untreated control. Hoeing in 50 cm inter-row spacing resulted in equal yield as the herbicide treatment. In 2022, weed control treatments and inter-row spacing had no effect on oilseed rape biomass, root diameter and yield. This study shows the potential and limitations of weed hoeing in oilseed rape. It also underlines the strong ability of modern oilseed rape cultivars to suppress annual broadleaved weeds.