Sensor-Guided Mechanical Weed Control in Transplanted Lettuce and Cabbage

• DOI: 10.1007/s10343-025-01139-3
• Publication Date: 2025-03-17T17:28:27Z
• Authors: Roland Gerhards; Michael Spaeth; Alexandra Heyn; Marcus Saile

Abstract Effective weed control is extremely important in vegetable production because weeds affect yield and quality of vegetable crops. Usually, only combinations of preventive and direct weed control methods can sufficiently suppress weeds. Therefore, costs for weeding are much higher in vegetables compared to most arable crops. Due to restrictions for herbicide use in vegetables, alternative and efficient direct weeding methods are urgently needed. Six field experiments with transplanted cabbage and lettuce were conducted in Southwestern Germany to quantify the weed control efficacy (WCE) and crop response of sensor-guided mechanical weed control methods with different degrees of automation. A camera-guided inter-row hoe with automatic side-shift control alone and combined with intra-row finger weeders and a camera-guided intra-row hoeing (robot) were compared to standard mechanical weeding, a broadcast herbicide treatment and an untreated control. Weed densities prior to treatment averaged 58 plants m−2 in cabbage and 18 plants m−2 in lettuce. Chenopodium album, Amaranthus retroflexus, Thlaspi arvense, Solanum nigrum and Digitaria sanguinalis were the dominating species. Until harvest, 80% weed coverage was measured in the untreated plots of cabbage and 28% in lettuce, which caused 56% yield loss in cabbage and 28% yield loss in lettuce. The highest WCE was achieved with the robot (87% inter-row and 84% intra-row) The broadcast herbicide treatment achieved 84% WCE for both inter-row and intra-row areas. Conventional inter-row hoeing had the lowest WCE of 73% inter-row and 35% intra-row. Camera-guided inter-row hoeing increased inter-row WCE to 80% and intra-row WCE to 56%. Finger weeding increased intra-row WCE in lettuce and cabbage to 54% with conventional hoeing and 62% with camera-guided hoeing. Camera-guidance reduced crop plant losses by 50% (from 9.1 to 4.5%) and increased crop yield by 13% compared to conventional hoeing. This study highlights the benefits of camera-guidance, AI-based weed detection and robotic weeding in transplanted vegetable crops.