Weed control in medicinal and aromatic plants (MAP) is particularly challenging as many species have a low competitiveness at early growth stages. Intra-row (within the row) mechanical weed control is most challenging since crops may be damaged as well. Here we compared five different devices for mechanical intra-row weeding (finger, torsion and rotative weeders, tine harrow, ridger share) in lemon balm and parsley, focusing on the critical stage of crop establishment. In total, eight field trials were carried out in 2020 and 2021 at two experimental farms of the University Bonn in the west of Germany. The devices were tested in replicated trials after optimising the settings on test plots. Data on weed control efficacy (WCE) and crop damage were analysed with ANOVA. The average WCE was 66 % and had a high variability ranging from 0 % to 100 %. Tine harrows could be applied most often and at earlier growth stages, followed by finger weeder. Highest crop damage was noted after use of rotative weeder. Yield decreasing effects were only significant in two cases and tended to be lower in transplanted than in sown lemon balm and parsley. However, due to variable operating conditions a consistent ranking of weeding devices was not possible. We conclude that despite significant technical progress during the last two decades, a complete replacement of herbicides is difficult at present, unless weed control is carried out manually. Further research is needed to ascertain under which environmental and management conditions mechanical intra-row weeding is most effective in the field, and how these techniques can be best integrated with other weed control methods.

A field experiment replicated over two seasons examined allelopathic effects of eleven sorghum accessions with known sorgoleone content on sorghum growth and yield, weed density and biomass at Panmure Experiment Station, in Shamva, Zimbabwe in the 2017/2018 summer and in late winter to summer in 2018. The trial was a 2 x 11 factorial in a randomized complete block design plus two control treatments replicated thrice. Factor A was weeding regime with two levels: clean weeding and no weeding. Factor B were 11 sorghum accessions. There was a significant sorghum accession x weeding regime interaction effect (p 0.05) between sorgoleone content and weed density and biomass, suggesting that sorgoleone may not instantly cause allelopathic effects on weeds upon its release from root hairs because it is strongly sorbed in soil, and inhibition of density and biomass might have been caused by other allelopathic compounds. Future research should trace uptake and translocation of allelopathic compounds to target sites of receiver plants, and demonstrate that subsequent damage symptoms are caused by the allelopathic compounds.

Smart weeding machine is an important tool for control of farmland weeds. To solve the high power consumption, low weeding rate, and high seedling damage rate of existing smart weeding machine in wheat fields, a power consumption model was established for the weed-soil- machine interactions process and a hob-type smart weeding machine of wheat fields was designed. The cutting-edge angle, roller radius, number of hob blades, and hob blade thickness were separately 20 degrees, 85 mm, 8, and 2 mm. A three-dimensional (3-d) structural model of the hob-type smart weeding machine was established on ProE and the operation process of the smart weeding machine's actuator was dynamically simulated in the discrete element method environment. On this basis, changes in performance indices including the operating width, operating depth, soil-throwing width, accumulation thickness, and average power consumption during the operation were investigated. Field tests of the hobtype smart weeding machine show that the operation width is 202.8 mm, which covers the inter-row area in wheat fields; the operation depth is 36 mm, at which roots of most weeds in wheat fields can be cut or pulled out; the soil-throwing width is 304.2 mm and the accumulation thickness is not higher than 20 mm, which is much lower than the height of wheat plants in the tillering stage. The average power during operation is 197.70 W, the weeding rate is 98.93 % and the seedling damage rate is 4.35 %. Compared to existing weeding machines reported, when the weed removal rates are similar, the power consumption of the weeding actuator developed in this study for wheat fields is reduced by approximately 54 %. On the premise of a comparable seedling damage rate, the weeding rate is increased by approximately 10 %, demonstrating notable characteristics of low power consumption and high efficiency.

Interrow weed control is used in a wide range of crops, traditionally applied via physical cultivation or banded herbicide application. However, these methods may result in crop damage, development of herbicide resistance, or off-target environmental impacts. Electric interrow weed control presents an alternative, although its potential impact on crop yield requires further investigation. One of the modes of action of electric weed control is the continuous electrode-plant contact method, which passes a current through the weed and into the roots. As the current passes into the roots, it can potentially disperse through the soil to neighboring root systems. Such off-target current dispersion, particularly in moist topsoil with low resistance, poses potential concern for neighboring crops when electric interrow weed control is applied. This research evaluated the continuous electrode-plant contact method, using a Zasso (TM) XPower machine, in comparison with mowing across three trials conducted in 2022 and 2023. Both treatments were used to remove target lupine (Lupinus albus L.) plants adjacent to a row of non-target lupine. Electric weed control was applied to plants in dry soil or following a simulated rainfall event. The trials demonstrated that electric weed control and mowing did not reduce density and biomass of neighboring non-target lupine plants compared with the untreated control. Likewise, pod and seed production, grain size, and protein, as well as grain germinability and vigor of the resulting seedlings, were not reduced by these weed control tactics. This research used technology that was not fit for purpose in broadscale grain crops but concludes that electric weed control via the continuous electrode-plant contact method or mowing did not result in crop damage. Therefore, it is unlikely that damage will occur using commercial-grade electric weed control or mowing technology designed for large-acreage interrow weed control, thus offering nonchemical weed management options.

Weeds compete with rice for sunlight and nutrients and are prone to harboring pathogens, leading to reduced rice yields. Addressing the issues of low weeding efficiency and weed mortality rates in existing inter-row weeding devices, the study proposes the design of a combination paddy field inter-row weeding wheel. The device's operation process is theoretically analyzed based on the weed control requirements in the northeastern region of China, leading to the determination of specific structural parameters. This research conducted experiments on the mechanical properties of weed cutting to obtain geometric parameters for paddy field weeds. It was found that the range for the cutting gap of the dynamic-fixed blade is between 0.6 mm to 1.4 mm and the cutting angle is between 5 degrees to 15 degrees, resulting in the lowest peak cutting force for weeds. Using LS-DYNA R12.0.0 dynamic simulation software, a fluid-structure interaction (FSI) model of the weeding wheel-water-soil system was established. By employing the central composite experimental design principle and considering the soil stir rate and coupling stress as indicators, the optimal structural parameter combination for the device is obtained: a dynamic-fixed blade cutting gap of 1.4 mm, a cutting angle of 10.95 degrees, and a dynamic blade install angle of -3.44 degrees. Field experiments demonstrated that the device achieved an average weeding rate of 89.7% and an average seedling damage rate of 1.9%, indicating excellent performance. This study contributes to improving weed mortality rates and provides valuable guidance for inter-row mechanical weeding technology.

Phytotoxicity refers to the capacity of chemical substances or environmental factors to have a negative impact on plants. This is a crucial issue in both the context of crop cultivation and environmental protection. The research results were based on a 3-year field experiment conducted at an experimental station in Jadwisin (52 degrees 28 ' N, 21 degrees 02 ' E) on loamy soil. The experiment was set up using a randomized sub-block design in a split-split-plot arrangement with three replications. The first-order factor consisted of potato cultivars, while the second-order factors were weed control methods: (1) without protection; (2) mechanical weed control, extensive mechanical treatments to close rows; (3) Sencor 70 WG-pre-emergence (PRE) of potatoes; (4) Sencor 70 WG + Titus 25 WG + Trend 90 EC-PRE of potatoes; (5) Sencor 70 WG-post-emergence (POST) of potatoes; (6) Sencor 70 WG + Titus 25 WG + Trend 90 EC-POST of potatoes; (7) Sencor 70 WG + Fusilade Forte 150 EC-POST of potatoes; and (8) Sencor 70 WG + Apyros 75 WG + Atpolan 80 SC-POST of potatoes. The phytotoxic effects of herbicides on potato plants and weeds were assessed every 7 days, starting from the date when the first signs of damage appeared until they stabilized or disappeared. Phytotoxic damage to potato and weed plants was caused by the chemical weed control methods used. The response of potato plants to herbicides was significantly related to the genetic traits of the cultivars and meteorological conditions in the years of research. Phytotoxicity is an important aspect in both agriculture and environmental protection. Research on its mechanisms and impact will enable the development of effective plant protection strategies and the preservation of ecosystem balance.

Weed harrowing is commonly used to manage weeds in organic farming but is also applied in conventional farming to replace herbicides. Due to its whole-field application, weed harrowing after crop emergence has relatively poor selectivity and may cause crop damage. Weediness generally varies within a field. Therefore, there is a potential to improve the selectivity and consider the within-field variation in weediness. This paper describes a decision model for precision post-emergence weed harrowing in cereals based on experimental data in spring barley and nonlinear regression analysis. The model predicts the optimal weed harrowing intensity in terms of the tine angle of the harrow for a given weediness (in terms of percentage weed cover), a given draft force of tines, and the biological weed damage threshold (in terms of percentage weed cover). Weed cover was measured with near-ground RGB images analyzed with a machine vision algorithm based on deep learning techniques. The draft force of tines was estimated with an electronic load cell. The proposed model is the first that uses a weed damage threshold in addition to site-specific values of weed cover and soil hardness to predict the site-specific optimal weed harrow tine angle. Future field trials should validate the suggested model.

This study focuses on real-time detection of maize crop rows using deep learning technology to meet the needs of autonomous navigation for weed removal during the maize seedling stage. Crop row recognition is affected by natural factors such as soil exposure, soil straw residue, mutual shading of plant leaves, and light conditions. To address this issue, the YOLOv5s network model is improved by replacing the backbone network with the improved MobileNetv3, establishing a combination network model YOLOv5-M3 and using the convolutional block attention module (CBAM) to enhance detection accuracy. Distance-IoU Non-Maximum Suppression (DIoU-NMS) is used to improve the identification degree of the occluded targets, and knowledge distillation is used to increase the recall rate and accuracy of the model. The improved YOLOv5s target detection model is applied to the recognition and positioning of maize seedlings, and the optimal target position for weeding is obtained by max-min optimization. Experimental results show that the YOLOv5-M3 network model achieves 92.2% mean average precision (mAP) for crop targets and the recognition speed is 39 frames per second (FPS). This method has the advantages of high detection accuracy, fast speed, and is light weight and has strong adaptability and anti-interference ability. It determines the relative position of maize seedlings and the weeding machine in real time, avoiding squeezing or damaging the seedlings.

Weeds in paddy fields can seriously reduce rice yield. An intra-row weeding device with double-layer elastic rods was designed, considering the differences in mechanical properties between rice and weeds, which can press weeds into the soil and avoid damaging rice. The elastic force of the elastic rods can be adjusted by changing the position of the regulating mechanism to adapt to different weeding conditions. A measurement experiment was conducted to determine the variation rule of elastic force. The quadratic orthogonal rotation combination discrete element simulation experiment, which used weeding depth and weeding speed as experimental factors, and the amount of soil disturbance and the force of the inner and outer elastic rod in the horizontal and vertical directions as experimental indicators, was conducted to study the interaction between the weeding device and the soil. The optimal weeding parameters were obtained: the weeding depth was 15 mm, the weeding speed was 0.9 m/s. The field experiment, which used the various parameters of the weeding device as experimental factors and the weeding rate and damaging seedling rate as experimental indicators, was conducted to determine the weeding effect. The experimental results showed that the optimal position of the regulating mechanism was 270 mm, with a weeding rate of 80.65% and a damaging seedling rate of 3.36%. The weeding rate can be increased by at least 11.18% by adjusting the regulating mechanism to a suitable position under the same weeding conditions. This study can provide a reference for research on weeding machinery for organic rice.

The increasing demand for alternatives to herbicides in weed management requires innovative approaches to integrated weed management, particularly due to the EU Soil Strategy1 which aims to reduce the use of pesticides in agriculture by 50% by 2030. Laser-based weed control provides an alternative to chemical methods allowing precise single plant weeding in the direct vicinity of crop plants. However, laser weeding must become more efficient and effective to compete with conventional methods. Optimizing the use of laser entails a wide array of parameters to analyze, such as laser wavelength, beam diameter, angle of irradiation and treatment point. Each parameter needs to be analyzed individually to gain knowledge of its effect on the laser weeding process. In this article, we show plant experiments to determine if the treatment point of the plant has an effect on the laser weeding process and which treatment point yields the highest success rate in damaging the plant. In a first set of experiments, we evaluated two potential treatment points of the plant: The meristem and the stem of the plant. We irradiated test plants with a 1940nm laser system, as this laser wavelength is well absorbed by the water within the plant, promising a high damage potential. We irradiated plants at a young growth stadium of up to four leaves and assessed each plant individually based on their damage level after a period of three weeks. To further improve our understanding of the laser weeding process, we recorded some experiments with a thermal imaging camera to visualize the heat distribution within the plant, as laser weeding is a thermal process, where heat is generated where the laser beam hits the plant.